At present,the cranes used at sea have several shortcomings in terms of flexibility,efficiency,and safety.Therefore,a floating multi-robot coordinated lifting system is proposed to fulfill the offshore lifting require...At present,the cranes used at sea have several shortcomings in terms of flexibility,efficiency,and safety.Therefore,a floating multi-robot coordinated lifting system is proposed to fulfill the offshore lifting requirements.First,the structure of the lifting system is established according to the lifting task,the kinematic model of the system is developed by using the D–H coordinate transformation,and the dynamic model is developed based on rigid-body dynamics and hydrodynamics.Then,the static and dynamic workspace of the lifting system are analyzed,and the solving steps of the workspace are given by using the Monte–Carlo method.The effect of the load mass and the maximum allowable tension of the cable on the workspace is examined by simulation.Results show that the lifting system has limited carrying capacity and a data reference for selecting the structural parameters by analyzing the factors affecting the workspace.Findings provide a basis for further research on the optimal design of structural parameters and the determination of safe configurations of the lifting system.展开更多
The southwest Lahad Datu felsic rocks were previously thought to have formed in the late Triassic as part of the microcontinental crystalline basement.Based on U-Pb ages,geochemistry,and the Hfisotopes of zircon from ...The southwest Lahad Datu felsic rocks were previously thought to have formed in the late Triassic as part of the microcontinental crystalline basement.Based on U-Pb ages,geochemistry,and the Hfisotopes of zircon from the southeastern Sabah gabbro and granite,in this study,the tectonic properties of the Sabah area during the Triassic were investigated.The weighted average U-Pb zircon ages of the gabbro and granite samples were determined to be(230.9±2.5)Ma and(207.1±3.3)Ma,respectively.The granite had SiO_(2) contents of 66.54%-79.47%,low TiO_(2) contents of 0.08%-0.3%,Al_(2)O_(3) contents of 10.97%-16.22%,Na_(2)O contents of 5.91 %-6.39%,and low K_(2)O contents of 0.15%-0.65%.The chondrite-normalized rare earth element(REE) patterns exhibit light REE enrichment,with right-sloping curves.The primitive mantle-normalized trace element spider diagrams exhibit Th,U,La,Sr,and Zr enrichment and Nb,Ta,P and Ti depletions,i.e.,the geochemical characteristics of typical island arc igneous rocks.The tectonic discriminant diagram indicates that the granite is a volcanic arc granite.The Hf isotopic an alysis of gabbro zircon revealed that the zircons have ε_(Hf)(t)values of 12.08-16.24(mean of 14.32) and two-stage model ages(t_(DM2)) of 223-491 Ma(mean of 347 Ma).This indicates that the diagenetic magma of the gabbro was mainly derived from melting of newly formed crustal materials.The ophiolite in southeast Sabah has existed since the early Late Triassic.The crystalline basement granite in southeastern S abah was emplaced lasted from late Triassic to early Cretaceous.Based on previous studies and global plate reconstruction models,it is speculated that the southeastern Sabah granite may have been formed in an island arc setting,i.e.,where the oceanic crust of the Paleo-Tethys Ocean collided with the oceanic crust of the Panthalassa Ocean.展开更多
Knowledge graph(KG)serves as a specialized semantic network that encapsulates intricate relationships among real-world entities within a structured framework.This framework facilitates a transformation in information ...Knowledge graph(KG)serves as a specialized semantic network that encapsulates intricate relationships among real-world entities within a structured framework.This framework facilitates a transformation in information retrieval,transitioning it from mere string matching to far more sophisticated entity matching.In this transformative process,the advancement of artificial intelligence and intelligent information services is invigorated.Meanwhile,the role ofmachine learningmethod in the construction of KG is important,and these techniques have already achieved initial success.This article embarks on a comprehensive journey through the last strides in the field of KG via machine learning.With a profound amalgamation of cutting-edge research in machine learning,this article undertakes a systematical exploration of KG construction methods in three distinct phases:entity learning,ontology learning,and knowledge reasoning.Especially,a meticulous dissection of machine learningdriven algorithms is conducted,spotlighting their contributions to critical facets such as entity extraction,relation extraction,entity linking,and link prediction.Moreover,this article also provides an analysis of the unresolved challenges and emerging trajectories that beckon within the expansive application of machine learning-fueled,large-scale KG construction.展开更多
The sedimentary system of Kalimantan has undergone significant development since the Oligocene.Previous research have largely ignored the capacity of the Cretaceous–Eocene sediments to produce hydrocarbons,focusing i...The sedimentary system of Kalimantan has undergone significant development since the Oligocene.Previous research have largely ignored the capacity of the Cretaceous–Eocene sediments to produce hydrocarbons,focusing instead primarily on the Oligocene–Miocene coal as the principal source rocks.Shales and coals from the outcrops in the northern margin of Kalimantan were analyzed with palynological and geochemical methods to characterize the palaeoenvironmental and palaeoecological differences between the Cretaceous–Eocene and the Oligocene–Miocene samples.The high proportion of Cheirolepidoaceae,Schizaeoisporites and Ephedripites in the pollen assemblage from the Cretaceous–Eocene outcrops reflects an arid tropical/subtropical climate.The relatively low abundances of gymnosperm-derived biomarkers including isopimarane,β-phyllocladane,β-kaurane,suggest the gymnosperm features in flora.High C_(27)/C_(29)ααα20R sterane ratios,(C_(19)–C_(29))tricyclic terpanes/C_(30)αβhopane and extremely low oleanane/C_(30)αβhopane,bicadinane T/C_(30)αβhopane,and diterpenoid abundance indicate that there was a dominance of algae relative to higher plants in the organic matter.The gymnosperm-derived biomarkers,including isopimarane,β-phyllocladane,β-kaurane,suggest that palaeovegetation during this period was dominated by gymnosperms.The saline and reducing conditions in the bathyal and abysmal sea,evidenced by rather low Pr/Ph and high Gammarerane index,are beneficial for the preservation of hydrogen-rich organic matter.It is presumed that the Cretaceous–Eocene shales had great hydrocarbon generation potential in the southern South China Sea.During the period of Oligocene to Miocene in the Zengmu Basin and the Baram-Sabah Basin,the climate changed to a dominant humid and warm condition,which is corroborated by abundant pollen of Florschuetzia and Magnastriatites hawardi.Low C_(27)/C_(29)ααα20R sterane ratios,(C_(19)–C_(29))tricyclic terpanes/C_(30)αβhopane,and high oleanane/C_(30)αβhopane,bicadinane T/C_(30)αβhopane suggest that the palaeovegetation was dominated by angiosperms including the mangrove plants.The extremely abundant higher plants provide ample terrigenous organic matter for the formation of coal-measures in delta facies.The low gammacerane index and high Pr/Ph indicate the fresh and sub-oxic water in delta-neriticabysmal faces,which is not beneficial for the accumulation of hydrogen-rich organic matter.Thus,the Oligocene–Miocene marine argillaceous rocks can be potential sources of natural gas.展开更多
This study involved outcrop,drilling,seismic,gravity,and magnetic data to systematically document the geological records of the subduction process of Proto-South China Sea(PSCS)and establish its evolution model.The re...This study involved outcrop,drilling,seismic,gravity,and magnetic data to systematically document the geological records of the subduction process of Proto-South China Sea(PSCS)and establish its evolution model.The results indicate that a series of arc-shaped ophiolite belts and calcalkaline magmatic rocks are developed in northern Borneo,both of which have the characteristics of gradually changing younger from west to east,and are direct signs of subduction and collision of PSCS.At the same time,the subduction of PSCS led to the formation of three accretion zones from the south to the north in Borneo,the Kuching belt,Sibu belt,and Miri belt.The sedimentary formation of northern Borneo is characterized by a three-layer structure,with the oceanic basement at the bottom,overlying the deep-sea flysch deposits of the Rajang–Crocker group,and the molasse sedimentary sequence that is dominated by river-delta and shallow marine facies at the top,recording the whole subduction–collision–orogeny process of PSCS.Further,seismic reflection and tomography also confirmed the subduction and collision of PSCS.Based on the geological records of the subduction and collision of PSCS,combined with the comprehensive analysis of segmented expansion and key tectonic events in the South China Sea,we establish the“gradual”subduction-collision evolution model of PSCS.During the late Eocene to middle Miocene,the Zengmu,Nansha,and Liyue–Palawan blocks were separated by West Baram Line and Balabac Fault,which collided with the Borneo block and Kagayan Ridge successively from the west to the east,forming several foreland basin systems,and PSCS subducted and closed from the west to the east.The subduction and extinction of PSCS controlled the oil and gas distribution pattern of southern South China Sea(SSCS)mainly in three aspects.First,the“gradual”closure process of PSCS led to the continuous development of many large deltas in SSCS.Second,the deltas formed during the subduction–collision of PSCS controlled the development of source rocks in the basins of SSCS.Macroscopically,the distribution and scale of deltas controlled the distribution and scale of source rocks,forming two types of source rocks,namely,coal measures and terrestrial marine facies.Microscopically,the difference of terrestrial higher plants carried by the delta controlled the proportion of macerals of source rocks.Third,the difference of source rocks mainly controlled the distribution pattern of oil and gas in SSCS.Meanwhile,the difference in the scale of source rocks mainly controlled the difference in the amount of oil and gas discoveries,resulting in a huge amount of oil and gas discoveries in the basin of SSCS.Meanwhile,the difference of macerals of source rocks mainly controlled the difference of oil and gas generation,forming the oil and gas distribution pattern of“nearshore oil and far-shore gas”.展开更多
Betula alnoides is a fast-growing hardwood species grown in large plantations in Southeast Asia and South China.Nitrogen requirements for producing robus seedlings,growth and nutrient dynamics were investigated using ...Betula alnoides is a fast-growing hardwood species grown in large plantations in Southeast Asia and South China.Nitrogen requirements for producing robus seedlings,growth and nutrient dynamics were investigated using exponential fertilization treatments.Root collar diameter,height,dry mass and nutrient contents of seedlings increased exponentially in all fertilization treatments as time progressed.Moreover,with water soluble fertilizer(Plant Products plus microelements N–P2O5–K2O:20–20–20),300 mg N seedling-1was adequate.Vector analysis revealed that P was the most responsive nutrient element followed by N and K.Dilutions of N and K were evident in the plants without N addition,which induced initial P sufficiency and then luxury consumption probably due to the antagonistic interaction between N and P.However deficiencies of N,P and K were mostly observed in al exponential regimes during the experiment because seedling growth rate exceeded nutrient uptake rate,inferring that further study on improving the nutrient uptake efficiency is needed.Analysis of relationships among nutrient supply,dry mass,N content and N concentration demonstrated that 100–400 mg N seedling-1induced sufficiency to luxury consumption of nitrogen without significant change in dry mass,and 400 mg N seedling-1is recommended to apply for nutrient loading of seedlings before outplanting.The findings will help improve seedling quality and enhance the production of robust seedlings for plantation forestry of this species.展开更多
We studied the formation of heartwood in Ery- throphleumfordii Oliv., an endangered rosewood species, by cross-section analysis on 52 stumps aged 28-57 years and arbitrarily sampled from natural forests in South China...We studied the formation of heartwood in Ery- throphleumfordii Oliv., an endangered rosewood species, by cross-section analysis on 52 stumps aged 28-57 years and arbitrarily sampled from natural forests in South China. Width and area of heartwood were positively correlated with age and xylem width (XW), and were independent of annual radial growth. The proportions of heartwood and sapwood areas were equal at about 40 years. The heartwood formation pro- cess was simulated by linear regression of age and XW.展开更多
The seedlings of Halocnermum strobilaceum were cultivated in 0.5% hoagland nutrient solution containing 0.0%, 0.9%, 2.7% and 5.4% of NaC1 as well as composite salt (Na^+, Ca^2+, K^+, Si^4+) for 20 days; all the ...The seedlings of Halocnermum strobilaceum were cultivated in 0.5% hoagland nutrient solution containing 0.0%, 0.9%, 2.7% and 5.4% of NaC1 as well as composite salt (Na^+, Ca^2+, K^+, Si^4+) for 20 days; all the contents are in weight ratio. Succulent level, inorganic ions (Na^+, K^+), organics such as betaine, proline, malondialdehyde, and antioxidant enzyme activities including superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), betaine aldehyde dehydrogenase (BADH) were measured to reveal its salt tolerance mechanism. When the composite salt concentration reaches 5.4%, SOD activity level, and MDA content is five times the control group; when it reaches 2.7%, the succulent level of seedlings, and the content ofK+ in roots is nearly two times the NaCl treatment; the dry weight is more than three times the control group; with the NaCl treatment, MDA is three times the contrast; when the salt concentration is 2.7%, POD reaches the maximum. Results indicate that Si^4+, K^+, and Ca^20 from composite salt in the roots of H. strobilaceum improved the water-holding capacity. The activities of antioxidant enzyme were raised by the accumulation ofproline and betaine, which increased the salt tolerance. The absorption of K^+ promoted the high ratio of K^+/Na^+ and alleviated the damage of cell membranes of H. strobilaceum, which is associated with osmotic contents such as betaine and proline.展开更多
Nowadays short texts can be widely found in various social data in relation to the 5G-enabled Internet of Things (IoT). Short text classification is a challenging task due to its sparsity and the lack of context. Prev...Nowadays short texts can be widely found in various social data in relation to the 5G-enabled Internet of Things (IoT). Short text classification is a challenging task due to its sparsity and the lack of context. Previous studies mainly tackle these problems by enhancing the semantic information or the statistical information individually. However, the improvement achieved by a single type of information is limited, while fusing various information may help to improve the classification accuracy more effectively. To fuse various information for short text classification, this article proposes a feature fusion method that integrates the statistical feature and the comprehensive semantic feature together by using the weighting mechanism and deep learning models. In the proposed method, we apply Bidirectional Encoder Representations from Transformers (BERT) to generate word vectors on the sentence level automatically, and then obtain the statistical feature, the local semantic feature and the overall semantic feature using Term Frequency-Inverse Document Frequency (TF-IDF) weighting approach, Convolutional Neural Network (CNN) and Bidirectional Gate Recurrent Unit (BiGRU). Then, the fusion feature is accordingly obtained for classification. Experiments are conducted on five popular short text classification datasets and a 5G-enabled IoT social dataset and the results show that our proposed method effectively improves the classification performance.展开更多
Erythrophleum fordii Oliv.(Caesalpiniaceae)is a rosewood species naturally distributed in southeast Asia and south China,and the heartwood is commonly used for high-quality crafts and furniture.While there are differe...Erythrophleum fordii Oliv.(Caesalpiniaceae)is a rosewood species naturally distributed in southeast Asia and south China,and the heartwood is commonly used for high-quality crafts and furniture.While there are differences in heartwood development among single trees with distinct social status,the relationship between heartwood development and growth performance remains unclear.This information is essential to improve plantation management for high-yield heartwood production.Forty dominant,intermediate and suppressed trees were sampled from E.fordii plantations aged in 32-35 years in Pingxiang City,Guangxi,China.Stem analysis was carried out to determine horizontal and vertical variations of heartwood and sapwood.Number of annual rings,diameter and area of heartwood and sapwood as well as ratios of heartwood diameter and area at breast height were all significantly influenced by the social status of trees in stands(P<0.05).In these mid-aged plantations,E.fordii stems developed heartwood once the xylem diameter reached 5-10 cm,and then heartwood diameter and area increased with increasing xylem diameter.Heartwood ring numbers,diameter and area as well as their ratios decreased with increasing height,while sapwood ring numbers and diameter were relatively constant within the section where heartwood occurred.Heartwood and sapwood diameters were equal at heights of approximately 6-m for dominant,5-m for intermediate and 3-m for suppressed trees.Dominant trees differed considerably from intermediate and suppressed trees in heartwood volume,while heartwood volume ratios were all below 30%,and near 90%in the stem section below 8-m height regardless of social status.Relationship analysis showed that DBH was the most important factor influencing heartwood in even-aged stands.The findings provide evidence for crop tree selection,thinning regimes and reasonable management of plantations of E.fordii.展开更多
To prevent possible accidents,the study of data-driven analytics to predict hidden dangers in cloud service-based intelligent industrial production management has been the subject of increasing interest recently.A mac...To prevent possible accidents,the study of data-driven analytics to predict hidden dangers in cloud service-based intelligent industrial production management has been the subject of increasing interest recently.A machine learning algorithm that uses timeliness managing extreme learning machine is utilized in this article to achieve the above prediction.Compared with traditional learning algorithms,extreme learning machine(ELM) exhibits high performance because of its unique feature of a high generalization capability at a fast learning speed.Timeliness managing ELM is proposed by incorporating timeliness management scheme into ELM.When using the timeliness managing ELM scheme to predict hidden dangers,newly incremental data could be added prior to the historical data to maximize the contribution of the newly incremental training data,because the incremental data may be able to contribute reasonable weights to represent the current production situation according to practical analysis of accidents in some industrial productions.Experimental results from a coal mine show that the use of timeliness managing ELM can improve the prediction accuracy of hidden dangers with better stability compared with other similar machine learning methods.展开更多
Brassica rapa cuhivars Qinghaidahuang and Menyuan small rape were used as female parents and separately interspecifically hybridized with Zhongchijie- lan to artificially synthesize a number of Brasica napus resources...Brassica rapa cuhivars Qinghaidahuang and Menyuan small rape were used as female parents and separately interspecifically hybridized with Zhongchijie- lan to artificially synthesize a number of Brasica napus resources. Observation of meiosis, pollen fertility and pollen tube germination and analysis of self-compati- bility index of these artificial B. napus varieties were conducted. Results showed that pollen mother cells of artificial B. napus lines from two cross combinations all had normal chromosome behavior and high pollen fertility, but the selfing seed-setting and self-compatibility index varied extremely significantly; B. napus lines from cross combination Qinghaidahuang x Zhongchijidan are highly self-compatible, while B. napus lines from cross combination Menyuan small rape x Zhongchijielan are highly self-incompatible. This study analyzed the heredity laws of self-incompatibility trait in artificially synthesized lines and discussed applica- tion prospects of artificially synthesized self-incompatible B. napus lines in rapeseed production.展开更多
To the Editor:Current guidelines recommend that for patients with acute coronary syndrome(ACS)undergoing percutaneous coronary intervention(PCI),dual antiplatelet therapy(DAPT),preferably involving powerful P2Y_(12) r...To the Editor:Current guidelines recommend that for patients with acute coronary syndrome(ACS)undergoing percutaneous coronary intervention(PCI),dual antiplatelet therapy(DAPT),preferably involving powerful P2Y_(12) receptor inhibitors,including ticagrelor or prasugrel,should be used for at least 12 months.^([1–3])However,there is a lack of relevant evidence regarding the feasibility of de-escalation treatment and specific DAPT treatment regimens for ACS patient populations with high ischemic risk.展开更多
Nuclear engineering materials are required to possess outstanding extreme environmental tolerance and irradiation resistance.A promising novel pyrochlore-type of(Sm_(0.2)Eu_(0.2)Gd_(0.2)Dy_(0.2)Er_(0.2))2 Hf_(2)O_(7)h...Nuclear engineering materials are required to possess outstanding extreme environmental tolerance and irradiation resistance.A promising novel pyrochlore-type of(Sm_(0.2)Eu_(0.2)Gd_(0.2)Dy_(0.2)Er_(0.2))2 Hf_(2)O_(7)high-entropy ceramic(HE-RE2 Hf_(2)O_(7))for control rod was prepared by solid-state reaction method.The ion irradiation of HE-RE_(2) Hf_(2)O_(7)with 400 keV Kr+at 400℃was investigated using a 400 kV ion implanter and compared with single-component pyrochlore Gd2 Hf_(2)O_(7)to evaluate the irradiation resistance.For HE-RE2 Hf_(2)O_(7),the phase transition from pyrochlore to defective fluorite is revealed after irradiation at 60 dpa.After irradiation at 120 dpa,it maintained crystalline,which is comparable to Gd2 Hf_(2)O_(7)but superior to the titanate pyrochlores previously studied.Moreover,the lattice expansion of HE-RE2 Hf_(2)O_(7)(_(0.2)2%)is much lower than that of Gd2 Hf_(2)O_(7)(0.62%),indicating excellent irradiation damage resistance.Nanoindentation tests displayed an irradiation-induced increase in hardness and a decrease in elastic modulus by about 2.6%.Irradiation-induced segregation of elements is observed on the surface of irradiated samples.In addition,HE-RE2 Hf_(2)O_(7)demonstrates a more sluggish grain growth rate than Gd2 Hf_(2)O_(7)at 1200℃,suggesting better high-temperature stability.The linear thermal expansion coefficient of HE-RE2 Hf_(2)O_(7)is 10.7×10-6 K-1 at 298–1273 K.In general,it provides a new strategy for the design of the next advanced nuclear engineering materials.展开更多
With the increasing interest in the application of electrochromism to flexible and wearable electronics in recent years,flexible electrochromic devices(ECDs)that can function at extreme temperatures are required.Howev...With the increasing interest in the application of electrochromism to flexible and wearable electronics in recent years,flexible electrochromic devices(ECDs)that can function at extreme temperatures are required.However,the functionalities of flexible ECDs are severely hampered by the inadequate choice of electrolytes,which might ultimately result in performance fading during low-and high-temperature operations.Here,we develop a deep eutectic solvent(DES)-based gel electrolyte that can maintain its optical,electrical,and mechanical properties over a wide range of temperatures(-40 to 150℃),exhibiting an extremely high visible-range transmittance over 90%,ion conductivity of 0.63 mS cm^(-1),and fracture strain exceeding 2000%.Owing to the excellent processability of the DES-based electrolytes,provided by dynamic interactions such as the lithium and hydrogen bonding between the DES and polymer matrix,a directly written patterning in ECDs is realized for the first time.The fabricated ECDs exhibit an excellent electrochromic behavior superior to the behavior of the ECDs fabricated with traditional gel electrolytes.The introduction of such DES-based electrolytes is expected to pave the way for a widespread application of electrochromic products.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No.51965032the National Natural Science Foundation of Gansu Province of China under Grant No.22JR5RA319+1 种基金the Science and Technology Foundation of Gansu Province of China under Grant No.21YF5WA060the Excellent Doctoral Student Foundation of Gansu Province of China under Grant No.23JRRA842。
文摘At present,the cranes used at sea have several shortcomings in terms of flexibility,efficiency,and safety.Therefore,a floating multi-robot coordinated lifting system is proposed to fulfill the offshore lifting requirements.First,the structure of the lifting system is established according to the lifting task,the kinematic model of the system is developed by using the D–H coordinate transformation,and the dynamic model is developed based on rigid-body dynamics and hydrodynamics.Then,the static and dynamic workspace of the lifting system are analyzed,and the solving steps of the workspace are given by using the Monte–Carlo method.The effect of the load mass and the maximum allowable tension of the cable on the workspace is examined by simulation.Results show that the lifting system has limited carrying capacity and a data reference for selecting the structural parameters by analyzing the factors affecting the workspace.Findings provide a basis for further research on the optimal design of structural parameters and the determination of safe configurations of the lifting system.
基金The National Science and Technology Major Project under contract No. 2016ZX05026-004the National Key R&D Program of China under contract No. 2019YFC0605402the National Natural Science Foundation of China under contract No.41790453。
文摘The southwest Lahad Datu felsic rocks were previously thought to have formed in the late Triassic as part of the microcontinental crystalline basement.Based on U-Pb ages,geochemistry,and the Hfisotopes of zircon from the southeastern Sabah gabbro and granite,in this study,the tectonic properties of the Sabah area during the Triassic were investigated.The weighted average U-Pb zircon ages of the gabbro and granite samples were determined to be(230.9±2.5)Ma and(207.1±3.3)Ma,respectively.The granite had SiO_(2) contents of 66.54%-79.47%,low TiO_(2) contents of 0.08%-0.3%,Al_(2)O_(3) contents of 10.97%-16.22%,Na_(2)O contents of 5.91 %-6.39%,and low K_(2)O contents of 0.15%-0.65%.The chondrite-normalized rare earth element(REE) patterns exhibit light REE enrichment,with right-sloping curves.The primitive mantle-normalized trace element spider diagrams exhibit Th,U,La,Sr,and Zr enrichment and Nb,Ta,P and Ti depletions,i.e.,the geochemical characteristics of typical island arc igneous rocks.The tectonic discriminant diagram indicates that the granite is a volcanic arc granite.The Hf isotopic an alysis of gabbro zircon revealed that the zircons have ε_(Hf)(t)values of 12.08-16.24(mean of 14.32) and two-stage model ages(t_(DM2)) of 223-491 Ma(mean of 347 Ma).This indicates that the diagenetic magma of the gabbro was mainly derived from melting of newly formed crustal materials.The ophiolite in southeast Sabah has existed since the early Late Triassic.The crystalline basement granite in southeastern S abah was emplaced lasted from late Triassic to early Cretaceous.Based on previous studies and global plate reconstruction models,it is speculated that the southeastern Sabah granite may have been formed in an island arc setting,i.e.,where the oceanic crust of the Paleo-Tethys Ocean collided with the oceanic crust of the Panthalassa Ocean.
基金supported in part by the Beijing Natural Science Foundation under Grants L211020 and M21032in part by the National Natural Science Foundation of China under Grants U1836106 and 62271045in part by the Scientific and Technological Innovation Foundation of Foshan under Grants BK21BF001 and BK20BF010。
文摘Knowledge graph(KG)serves as a specialized semantic network that encapsulates intricate relationships among real-world entities within a structured framework.This framework facilitates a transformation in information retrieval,transitioning it from mere string matching to far more sophisticated entity matching.In this transformative process,the advancement of artificial intelligence and intelligent information services is invigorated.Meanwhile,the role ofmachine learningmethod in the construction of KG is important,and these techniques have already achieved initial success.This article embarks on a comprehensive journey through the last strides in the field of KG via machine learning.With a profound amalgamation of cutting-edge research in machine learning,this article undertakes a systematical exploration of KG construction methods in three distinct phases:entity learning,ontology learning,and knowledge reasoning.Especially,a meticulous dissection of machine learningdriven algorithms is conducted,spotlighting their contributions to critical facets such as entity extraction,relation extraction,entity linking,and link prediction.Moreover,this article also provides an analysis of the unresolved challenges and emerging trajectories that beckon within the expansive application of machine learning-fueled,large-scale KG construction.
基金The National Science and Technology Major Project under contract No.2016ZX05026-004。
文摘The sedimentary system of Kalimantan has undergone significant development since the Oligocene.Previous research have largely ignored the capacity of the Cretaceous–Eocene sediments to produce hydrocarbons,focusing instead primarily on the Oligocene–Miocene coal as the principal source rocks.Shales and coals from the outcrops in the northern margin of Kalimantan were analyzed with palynological and geochemical methods to characterize the palaeoenvironmental and palaeoecological differences between the Cretaceous–Eocene and the Oligocene–Miocene samples.The high proportion of Cheirolepidoaceae,Schizaeoisporites and Ephedripites in the pollen assemblage from the Cretaceous–Eocene outcrops reflects an arid tropical/subtropical climate.The relatively low abundances of gymnosperm-derived biomarkers including isopimarane,β-phyllocladane,β-kaurane,suggest the gymnosperm features in flora.High C_(27)/C_(29)ααα20R sterane ratios,(C_(19)–C_(29))tricyclic terpanes/C_(30)αβhopane and extremely low oleanane/C_(30)αβhopane,bicadinane T/C_(30)αβhopane,and diterpenoid abundance indicate that there was a dominance of algae relative to higher plants in the organic matter.The gymnosperm-derived biomarkers,including isopimarane,β-phyllocladane,β-kaurane,suggest that palaeovegetation during this period was dominated by gymnosperms.The saline and reducing conditions in the bathyal and abysmal sea,evidenced by rather low Pr/Ph and high Gammarerane index,are beneficial for the preservation of hydrogen-rich organic matter.It is presumed that the Cretaceous–Eocene shales had great hydrocarbon generation potential in the southern South China Sea.During the period of Oligocene to Miocene in the Zengmu Basin and the Baram-Sabah Basin,the climate changed to a dominant humid and warm condition,which is corroborated by abundant pollen of Florschuetzia and Magnastriatites hawardi.Low C_(27)/C_(29)ααα20R sterane ratios,(C_(19)–C_(29))tricyclic terpanes/C_(30)αβhopane,and high oleanane/C_(30)αβhopane,bicadinane T/C_(30)αβhopane suggest that the palaeovegetation was dominated by angiosperms including the mangrove plants.The extremely abundant higher plants provide ample terrigenous organic matter for the formation of coal-measures in delta facies.The low gammacerane index and high Pr/Ph indicate the fresh and sub-oxic water in delta-neriticabysmal faces,which is not beneficial for the accumulation of hydrogen-rich organic matter.Thus,the Oligocene–Miocene marine argillaceous rocks can be potential sources of natural gas.
基金The National Natural Science Foundation of China under contract No.91528303the National Science and Technology Major Project under contract No.2016ZX05026-004the CNOOC Basic Geology and Exploration Strategy of Natural Gas in the South China Sea under contract No.2021-KT-YXKY-05。
文摘This study involved outcrop,drilling,seismic,gravity,and magnetic data to systematically document the geological records of the subduction process of Proto-South China Sea(PSCS)and establish its evolution model.The results indicate that a series of arc-shaped ophiolite belts and calcalkaline magmatic rocks are developed in northern Borneo,both of which have the characteristics of gradually changing younger from west to east,and are direct signs of subduction and collision of PSCS.At the same time,the subduction of PSCS led to the formation of three accretion zones from the south to the north in Borneo,the Kuching belt,Sibu belt,and Miri belt.The sedimentary formation of northern Borneo is characterized by a three-layer structure,with the oceanic basement at the bottom,overlying the deep-sea flysch deposits of the Rajang–Crocker group,and the molasse sedimentary sequence that is dominated by river-delta and shallow marine facies at the top,recording the whole subduction–collision–orogeny process of PSCS.Further,seismic reflection and tomography also confirmed the subduction and collision of PSCS.Based on the geological records of the subduction and collision of PSCS,combined with the comprehensive analysis of segmented expansion and key tectonic events in the South China Sea,we establish the“gradual”subduction-collision evolution model of PSCS.During the late Eocene to middle Miocene,the Zengmu,Nansha,and Liyue–Palawan blocks were separated by West Baram Line and Balabac Fault,which collided with the Borneo block and Kagayan Ridge successively from the west to the east,forming several foreland basin systems,and PSCS subducted and closed from the west to the east.The subduction and extinction of PSCS controlled the oil and gas distribution pattern of southern South China Sea(SSCS)mainly in three aspects.First,the“gradual”closure process of PSCS led to the continuous development of many large deltas in SSCS.Second,the deltas formed during the subduction–collision of PSCS controlled the development of source rocks in the basins of SSCS.Macroscopically,the distribution and scale of deltas controlled the distribution and scale of source rocks,forming two types of source rocks,namely,coal measures and terrestrial marine facies.Microscopically,the difference of terrestrial higher plants carried by the delta controlled the proportion of macerals of source rocks.Third,the difference of source rocks mainly controlled the distribution pattern of oil and gas in SSCS.Meanwhile,the difference in the scale of source rocks mainly controlled the difference in the amount of oil and gas discoveries,resulting in a huge amount of oil and gas discoveries in the basin of SSCS.Meanwhile,the difference of macerals of source rocks mainly controlled the difference of oil and gas generation,forming the oil and gas distribution pattern of“nearshore oil and far-shore gas”.
基金This work was supported by grants from the National Basic Research Program of China (973 Program, No. 2007CB914800 to Xiaodong Zhang), National Natural Science Foundation of China (No. 30570698 to Xiaodong Zhang) and Tianjin Natural Scientific Foundation (No. 033801211 to Xiaodong Zhang).
基金financially supported by The Ministry of Science and Technology,China(2012BAD21B0102)
文摘Betula alnoides is a fast-growing hardwood species grown in large plantations in Southeast Asia and South China.Nitrogen requirements for producing robus seedlings,growth and nutrient dynamics were investigated using exponential fertilization treatments.Root collar diameter,height,dry mass and nutrient contents of seedlings increased exponentially in all fertilization treatments as time progressed.Moreover,with water soluble fertilizer(Plant Products plus microelements N–P2O5–K2O:20–20–20),300 mg N seedling-1was adequate.Vector analysis revealed that P was the most responsive nutrient element followed by N and K.Dilutions of N and K were evident in the plants without N addition,which induced initial P sufficiency and then luxury consumption probably due to the antagonistic interaction between N and P.However deficiencies of N,P and K were mostly observed in al exponential regimes during the experiment because seedling growth rate exceeded nutrient uptake rate,inferring that further study on improving the nutrient uptake efficiency is needed.Analysis of relationships among nutrient supply,dry mass,N content and N concentration demonstrated that 100–400 mg N seedling-1induced sufficiency to luxury consumption of nitrogen without significant change in dry mass,and 400 mg N seedling-1is recommended to apply for nutrient loading of seedlings before outplanting.The findings will help improve seedling quality and enhance the production of robust seedlings for plantation forestry of this species.
基金financially supported by the Special Research Program for Public-welfare Forestry(No.201204301-2)National Nonprofit Institute Research Grant of RITF(No.RITFKYYW2010-05)
文摘We studied the formation of heartwood in Ery- throphleumfordii Oliv., an endangered rosewood species, by cross-section analysis on 52 stumps aged 28-57 years and arbitrarily sampled from natural forests in South China. Width and area of heartwood were positively correlated with age and xylem width (XW), and were independent of annual radial growth. The proportions of heartwood and sapwood areas were equal at about 40 years. The heartwood formation pro- cess was simulated by linear regression of age and XW.
基金funded by the National Natural Science Foundation of China(Grant Nos.31160118,31460162,31422011,31370402,and 30800122)
文摘The seedlings of Halocnermum strobilaceum were cultivated in 0.5% hoagland nutrient solution containing 0.0%, 0.9%, 2.7% and 5.4% of NaC1 as well as composite salt (Na^+, Ca^2+, K^+, Si^4+) for 20 days; all the contents are in weight ratio. Succulent level, inorganic ions (Na^+, K^+), organics such as betaine, proline, malondialdehyde, and antioxidant enzyme activities including superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), betaine aldehyde dehydrogenase (BADH) were measured to reveal its salt tolerance mechanism. When the composite salt concentration reaches 5.4%, SOD activity level, and MDA content is five times the control group; when it reaches 2.7%, the succulent level of seedlings, and the content ofK+ in roots is nearly two times the NaCl treatment; the dry weight is more than three times the control group; with the NaCl treatment, MDA is three times the contrast; when the salt concentration is 2.7%, POD reaches the maximum. Results indicate that Si^4+, K^+, and Ca^20 from composite salt in the roots of H. strobilaceum improved the water-holding capacity. The activities of antioxidant enzyme were raised by the accumulation ofproline and betaine, which increased the salt tolerance. The absorption of K^+ promoted the high ratio of K^+/Na^+ and alleviated the damage of cell membranes of H. strobilaceum, which is associated with osmotic contents such as betaine and proline.
基金supported in part by the Beijing Natural Science Foundation under grants M21032 and 19L2029in part by the National Natural Science Foundation of China under grants U1836106 and 81961138010in part by the Scientific and Technological Innovation Foundation of Foshan under grants BK21BF001 and BK20BF010.
文摘Nowadays short texts can be widely found in various social data in relation to the 5G-enabled Internet of Things (IoT). Short text classification is a challenging task due to its sparsity and the lack of context. Previous studies mainly tackle these problems by enhancing the semantic information or the statistical information individually. However, the improvement achieved by a single type of information is limited, while fusing various information may help to improve the classification accuracy more effectively. To fuse various information for short text classification, this article proposes a feature fusion method that integrates the statistical feature and the comprehensive semantic feature together by using the weighting mechanism and deep learning models. In the proposed method, we apply Bidirectional Encoder Representations from Transformers (BERT) to generate word vectors on the sentence level automatically, and then obtain the statistical feature, the local semantic feature and the overall semantic feature using Term Frequency-Inverse Document Frequency (TF-IDF) weighting approach, Convolutional Neural Network (CNN) and Bidirectional Gate Recurrent Unit (BiGRU). Then, the fusion feature is accordingly obtained for classification. Experiments are conducted on five popular short text classification datasets and a 5G-enabled IoT social dataset and the results show that our proposed method effectively improves the classification performance.
基金This study is supported by the Fundamental Research Funds for the Central Non-profit Research Institution of CAF(Grant No.CAFYBB2017MB019).
文摘Erythrophleum fordii Oliv.(Caesalpiniaceae)is a rosewood species naturally distributed in southeast Asia and south China,and the heartwood is commonly used for high-quality crafts and furniture.While there are differences in heartwood development among single trees with distinct social status,the relationship between heartwood development and growth performance remains unclear.This information is essential to improve plantation management for high-yield heartwood production.Forty dominant,intermediate and suppressed trees were sampled from E.fordii plantations aged in 32-35 years in Pingxiang City,Guangxi,China.Stem analysis was carried out to determine horizontal and vertical variations of heartwood and sapwood.Number of annual rings,diameter and area of heartwood and sapwood as well as ratios of heartwood diameter and area at breast height were all significantly influenced by the social status of trees in stands(P<0.05).In these mid-aged plantations,E.fordii stems developed heartwood once the xylem diameter reached 5-10 cm,and then heartwood diameter and area increased with increasing xylem diameter.Heartwood ring numbers,diameter and area as well as their ratios decreased with increasing height,while sapwood ring numbers and diameter were relatively constant within the section where heartwood occurred.Heartwood and sapwood diameters were equal at heights of approximately 6-m for dominant,5-m for intermediate and 3-m for suppressed trees.Dominant trees differed considerably from intermediate and suppressed trees in heartwood volume,while heartwood volume ratios were all below 30%,and near 90%in the stem section below 8-m height regardless of social status.Relationship analysis showed that DBH was the most important factor influencing heartwood in even-aged stands.The findings provide evidence for crop tree selection,thinning regimes and reasonable management of plantations of E.fordii.
基金partially supported by the National Key Technologies R&D Program of China under Grant No.2015BAK38B01the National Natural Science Foundation of China under Grant Nos.61174103 and 61272357the Fundamental Research Funds for the Central Universities under Grant No.06500025
文摘To prevent possible accidents,the study of data-driven analytics to predict hidden dangers in cloud service-based intelligent industrial production management has been the subject of increasing interest recently.A machine learning algorithm that uses timeliness managing extreme learning machine is utilized in this article to achieve the above prediction.Compared with traditional learning algorithms,extreme learning machine(ELM) exhibits high performance because of its unique feature of a high generalization capability at a fast learning speed.Timeliness managing ELM is proposed by incorporating timeliness management scheme into ELM.When using the timeliness managing ELM scheme to predict hidden dangers,newly incremental data could be added prior to the historical data to maximize the contribution of the newly incremental training data,because the incremental data may be able to contribute reasonable weights to represent the current production situation according to practical analysis of accidents in some industrial productions.Experimental results from a coal mine show that the use of timeliness managing ELM can improve the prediction accuracy of hidden dangers with better stability compared with other similar machine learning methods.
基金Supported by National Natural Science Foundation of China(30960200)National Science and Technology Support Program of China(2011BAD35B04)Applied Basic Research Project of Qinghai Province(2011-Z-701)
文摘Brassica rapa cuhivars Qinghaidahuang and Menyuan small rape were used as female parents and separately interspecifically hybridized with Zhongchijie- lan to artificially synthesize a number of Brasica napus resources. Observation of meiosis, pollen fertility and pollen tube germination and analysis of self-compati- bility index of these artificial B. napus varieties were conducted. Results showed that pollen mother cells of artificial B. napus lines from two cross combinations all had normal chromosome behavior and high pollen fertility, but the selfing seed-setting and self-compatibility index varied extremely significantly; B. napus lines from cross combination Qinghaidahuang x Zhongchijidan are highly self-compatible, while B. napus lines from cross combination Menyuan small rape x Zhongchijielan are highly self-incompatible. This study analyzed the heredity laws of self-incompatibility trait in artificially synthesized lines and discussed applica- tion prospects of artificially synthesized self-incompatible B. napus lines in rapeseed production.
基金supported by the Self-financing Project of Lang Fang Science and Technology Research and Development Plan(Nos.2022013038 and 2020013106)Guiding Project of Hebei Medical Science Research Program(No.20232053)
文摘To the Editor:Current guidelines recommend that for patients with acute coronary syndrome(ACS)undergoing percutaneous coronary intervention(PCI),dual antiplatelet therapy(DAPT),preferably involving powerful P2Y_(12) receptor inhibitors,including ticagrelor or prasugrel,should be used for at least 12 months.^([1–3])However,there is a lack of relevant evidence regarding the feasibility of de-escalation treatment and specific DAPT treatment regimens for ACS patient populations with high ischemic risk.
基金supported by the Lingchuang Research Project of China National Nuclear Corporation,the National Key Research and Development Program of China(No.2022YFB3504302)the key core technology research project in Beicang District,Ningbo(Grant No.2021BLG009)+4 种基金the key deployment project of the Chinese Academy of Sciences(Grant No.ZDRW-CN-2021-3)the Fujian Provincial Natural Fund Project(Grant No.2021J05101)the Young Elite Scientists Sponsorship Program by CAST(Grant No.2021QNRC001)the independent deployment project of Ganjiang Innovation Research Institute of Chinese Academy of Sciences(Grant No.E055A002)In addition,thanks for the assistance of Jinchi Huang from the School of Energy,Xiamen University for the ion irradiation experiment.
文摘Nuclear engineering materials are required to possess outstanding extreme environmental tolerance and irradiation resistance.A promising novel pyrochlore-type of(Sm_(0.2)Eu_(0.2)Gd_(0.2)Dy_(0.2)Er_(0.2))2 Hf_(2)O_(7)high-entropy ceramic(HE-RE2 Hf_(2)O_(7))for control rod was prepared by solid-state reaction method.The ion irradiation of HE-RE_(2) Hf_(2)O_(7)with 400 keV Kr+at 400℃was investigated using a 400 kV ion implanter and compared with single-component pyrochlore Gd2 Hf_(2)O_(7)to evaluate the irradiation resistance.For HE-RE2 Hf_(2)O_(7),the phase transition from pyrochlore to defective fluorite is revealed after irradiation at 60 dpa.After irradiation at 120 dpa,it maintained crystalline,which is comparable to Gd2 Hf_(2)O_(7)but superior to the titanate pyrochlores previously studied.Moreover,the lattice expansion of HE-RE2 Hf_(2)O_(7)(_(0.2)2%)is much lower than that of Gd2 Hf_(2)O_(7)(0.62%),indicating excellent irradiation damage resistance.Nanoindentation tests displayed an irradiation-induced increase in hardness and a decrease in elastic modulus by about 2.6%.Irradiation-induced segregation of elements is observed on the surface of irradiated samples.In addition,HE-RE2 Hf_(2)O_(7)demonstrates a more sluggish grain growth rate than Gd2 Hf_(2)O_(7)at 1200℃,suggesting better high-temperature stability.The linear thermal expansion coefficient of HE-RE2 Hf_(2)O_(7)is 10.7×10-6 K-1 at 298–1273 K.In general,it provides a new strategy for the design of the next advanced nuclear engineering materials.
基金External Cooperation Program of the Chinese Academy of Sciences,Grant/Award Number:121E32KYSB20190008National Natural Science Foundation of China,Grant/Award Numbers:22175198,51972331,52172299+3 种基金Outstanding Youth Fund of Jiangxi,Grant/Award Number:20192BCBL23027Six Talent Peaks Project in Jiangsu Province,Grant/Award Number:XCL-170the National Key Research and Development Program of China,Grant/Award Number:2020YFB1505703Youth Innovation Promotion Association of the Chinese Academy of Sciences,Grant/Award Number:2018356.
文摘With the increasing interest in the application of electrochromism to flexible and wearable electronics in recent years,flexible electrochromic devices(ECDs)that can function at extreme temperatures are required.However,the functionalities of flexible ECDs are severely hampered by the inadequate choice of electrolytes,which might ultimately result in performance fading during low-and high-temperature operations.Here,we develop a deep eutectic solvent(DES)-based gel electrolyte that can maintain its optical,electrical,and mechanical properties over a wide range of temperatures(-40 to 150℃),exhibiting an extremely high visible-range transmittance over 90%,ion conductivity of 0.63 mS cm^(-1),and fracture strain exceeding 2000%.Owing to the excellent processability of the DES-based electrolytes,provided by dynamic interactions such as the lithium and hydrogen bonding between the DES and polymer matrix,a directly written patterning in ECDs is realized for the first time.The fabricated ECDs exhibit an excellent electrochromic behavior superior to the behavior of the ECDs fabricated with traditional gel electrolytes.The introduction of such DES-based electrolytes is expected to pave the way for a widespread application of electrochromic products.