检索结果-南通市图书馆

Science China(Technological Sciences) 2024年第6期67卷 1893-1906页

作者： AN kai wang ZhenGuo HUANG Wei Hypersonic Technology Laboratory National University of Defense TechnologyChangsha410073China

We propose an adaptive learning-based optimal control scheme for height-velocity control models considering model uncertainties and external disturbances of hypersonic winged-cone *** longitudinal nonlinear model is first established and transformed into the control-oriented error equations,and the control scheme is organized by a steady-compensation *** overcome and eliminate the impact of model uncertainties and external disturbances,an adaptive radial basis function neural network(RBFNN)is designed by a q-gradient *** the height-velocity error system with estimated uncertainties into account,the adaptive learning-based optimal tracking control(ALOTC)scheme is proposed by combining the critic-only adaptive dynamic programming(ADP)framework and parameter optimization of system settling ***,a novel weight update law is proposed to satisfy the online iteration requirements,and the algorithm convergence and closedloop stability are discussed by the Lyapunov ***,four simulation cases are provided to prove the effectiveness,accuracy,and robustness of the proposed scheme for the hypersonic longitudinal control system.

关键词： optimal tracking control adaptive dynamic programming RBFNN hypersonic vehicle

Nondestructive Nonlinear Optical Microscopy Revealed the Blackening Mechanism of Ancient Chinese Jades

在线全文

学校读者我要写书评

暂无评论

Research 2024年第3期2023卷 391-399页

作者： Yaxin Chen rong wang Minbiao Ji State Key Laboratory of Surface Physics and Department of Physics Human Phenome InstituteAcademy for Engineering and TechnologyKey Laboratory of Micro and Nano Photonic Structures(Ministry of Education)Yiwu Research Institute of Fudan UniversityFudan UniversityShanghai 200433China Department of Cultural Heritage and Museology Fudan UniversityShanghaiChina

Jade is most valued in Chinese culture since ancient times. For unearthed jade artifacts, the alteration color resulting from weathering effects and human activities provides information for cultural heritage conservation, archaeology, and history. Currently, the noninvasive 3-dimensional characterization of jade artifacts with high chemical and spatial resolution remains challenging. In this work, we applied femtosecond pump–probe microscopy and second harmonic generation microscopy techniques to study the black alteration of an ancient jade artifact of the late Spring and Autumn period (546 to 476 BC). The direct cause of the “mercury alteration” phenomena was discovered to be the conversion of metacinnabar from buried cinnabar in the tomb. Furthermore, a 3-dimensional optical reconstruction of the black alteration was achieved, providing a high-resolution method for analyzing the blackening mechanism without the need of sample damage. Our approach opens up new opportunities to extract microscopic spatiochemical information for a broad range of alteration colors in jade artifacts.

关键词： pump Nonlinear buried

On the Optimal Initial Inner-Core Size for Tropical Cyclone Intensification: An Idealized Numerical Study

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

Advances in Atmospheric Sciences 2024年第11期41卷 2141-2155页

作者： rong FEI Yuqing wang School of Atmospheric Sciences and Remote Sensing Wuxi UniversityWuxi 214105China State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesBeijing 100081China International Pacific Research Center Department of Atmospheric SciencesSchool of Ocean and Earth Science and TechnologyUniversity of Hawaii at ManoaHonoluluHawaii 96822USA

Recent observational and numerical studies have revealed the dependence of the intensification rate on the inner-core size of tropical cyclones(TCs). In this study, with the initial inner-core size(i.e., the radius of maximum wind—RMW)varied from 20–180 km in idealized simulations using two different numerical models, we found a nonmonotonic dependence of the lifetime maximum intensification rate(LMIR) on the inner-core size. Namely, there is an optimal innercore size for the LMIR of a TC. Tangential wind budget analysis shows that, compared to large TCs, small TCs have large inward flux of absolute vorticity due to large absolute vorticity inside the RMW. However, small TCs also suffer from strong lateral diffusion across the eyewall, which partly offsets the positive contribution from large inward flux of absolute vorticity. These two competing processes ultimately lead to the TC with an intermediate initial inner-core size having the largest LMIR. Results from sensitivity experiments show that the optimal size varies in the range of 40–120 km and increases with higher sea surface temperature, lower latitude, larger horizontal mixing length, and weaker initial TC intensity. The 40–120 km RMW corresponds to the inner-core size most commonly found for intensifying TCs in observations, suggesting the natural selection of initial TC size for intensification. This study highlights the importance of accurate representation of TC inner-core size to TC intensity forecasts by numerical weather prediction models.

关键词： tropical cyclones intensification inner-core size idealized simulations

Plant Phosphorus Uptake in a Soybean-Citrus Intercropping System in the Red Soil Hilly Region of South China

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2009年第2期19卷 244-250页

作者： ZHOU Wei-Jun ZHANG Yang-Zhu wang kai-rong LI He-Song HAO Yin-Ju LIU Xin College of Resources and Environment Hunan Agricultural University Changsha 410128 China Institute of Subtropical Agriculture Chinese Academy of Sciences Changsha 410125 China

A field microplot experiment was conducted in the red soil hilly region of South China to evaluate plant phosphorus (P)uptake under soybean and citrus monoculture and the soybean-citrus intercropping system using the 32P tracer technique.P fertilizer was applied at three depths(15,35,and 55 cm).The experimental results showed that the planting pattern and 32P application depth significantly affected the characteristics of P uptake by soybean and *** the soybean-citrus intercropping system,considerable competition was observed when the 32P fertilizer was applied to the topsoil(15 cm);therefore,the 32P recovery rate declined by 41.5%and 14.7%for soybean and citrus,and 32P supplying amount of topsoil to soybean and citrus decreased by 346.8 and 148.1 mg plot-1,respectively,compared to those under the ***,32P recovery of soybean was promoted when 32P fertilizer was applied to the deeper soil layers (35 and 55 cm)under soybean-citrus *** the soybean monoculture,32P fertilizer could hardly be used by soybean when 32P fertilizer was applied at the 55 cm depth or below,with the recovery rate being less than 0.1%;it was up to 0.253%by soybean under *** higher P recovery of soybean under soybean-citrus intercropping when P was applied in the deeper soil layers was because part of the P nutrient that the citrus absorbed from the deeper soil layers could be released into the topsoil and then it could be used by the soybean.

关键词： citrus intercropping monoculture P uptake soybean

Autonomous navigation method of satellite constellation based on adaptive forgetting factors

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2024年第7期37卷 317-332页

作者： Dong wang Jing YANG kai XIONG School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100191China Science and Technology on Space Intelligent Control Laboratory Beijing Institute of Control EngineeringBeijing 100094China

To address the problem that model uncertainty and unknown time-varying system noise hinder the filtering accuracy of the autonomous navigation system of satellite constellation,an autonomous navigation method of satellite constellation based on the Unscented Kalman Filter with Adaptive Forgetting Factors(UKF-AFF)is *** process noise covariance matrix is estimated online with the strategy that combines covariance matching and adaptive adjustment of forgetting *** adaptive adjustment coefficient based on squared Mahalanobis distance of state residual is employed to achieve online regulation of forgetting factors,equipping this method with more *** intersatellite direction vector obtained from photographic observations is introduced to determine the constellation satellite orbit together with the distance measurement to avoid rank deficiency *** that the number of available measurements varies online with intersatellite visibility in practical applications such as time-varying constellation configurations,the smooth covariance matrix of state correction determined by innovation and gain is adopted and constructed *** analysis of the proposed method is also *** effectiveness of the proposed method is verified by the Monte Carlo simulation and comparison *** estimation accuracy of constellation position and velocity of UKF-AFF is improved by 30%and 44%respectively compared to those of the extended Kalman filter,and the method proposed is also better than other several adaptive filtering methods in the presence of significant model uncertainty.

关键词： Constellation autonomous navigation Unscented Kalman filter Adaptive forgetting factor Model uncertainty Stability analysis

Robustness of the octupole collectivity in 144Ba within the cranking covariant density functional theory in 3D lattice

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2024年第8期35卷 124-131页

作者： Ze‑kai Li Yuan‑Yuan wang Mathematics and Physics Department North China Electric Power UniversityBeijing 102206China Hebei Key Laboratory of Physics and Energy Technology North China Electric Power UniversityBaoding 071000China

The octupole deformation and collectivity in octupole double-magic nucleus 144Ba are investigated using the Cranking covariant density functional theory in a three-dimensional lattice *** reduced B(E3)transition probability is implemented for the first time in semiclassical approximation based on the microscopically calculated electric octupole *** available data,including the I-ωrelation and electric transitional probabilities B(E2)and B(E3)are well ***,it is shown that the ground state of 144Ba exhibits axial octupole and quadrupole deformations that persist up to high spins(I≈24h).

关键词： Octupole collectivity Cranking covariant density functional theory Rotational spectrum Electric transitional probabilities

Vibration Control of A Flexible Marine Riser System Subject to Input Dead Zone and Extraneous Disturbances

在线全文

学校读者我要写书评

暂无评论

China Ocean Engineering 2024年第2期38卷 271-284页

作者： ZHOU Li wang Guo-rong WAN Min School of Mechatronic Engineering Southwest Petroleum UniversityChengdu 610500China Energy Equipment Institute Southwest Petroleum UniversityChengdu 610500China National Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChengdu 610500China

An observer-based adaptive backstepping boundary control is proposed for vibration control of flexible offshore riser systems with unknown nonlinear input dead zone and uncertain environmental *** control algorithm can update the control law online through real-time data to make the controller adapt to the environment and improve the control ***,based on the adaptive backstepping framework,virtual control laws and Lyapunov functions are designed for each *** direction interference observers are designed to track the timevarying boundary *** this basis,the inverse of the dead zone and linear state transformation are used to compensate for the original system and eliminate the adverse effects of the dead *** addition,the stability of the closed-loop system is proven by Lyapunov stability *** the system states are bounded,and the vibration offset of the riser converges to a small area of the initial ***,four examples of flexible marine risers are simulated in MATLAB to verify the effectiveness of the proposed controller.

关键词： adaptive backstepping control disturbance observer flexible marine riser input dead zone vibration control

Transcriptional regulation in the development and dysfunction of neocortical projection neurons

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2024年第2期19卷 246-254页

作者： Ningxin wang rong Wan Ke Tang Precise Genome Engineering Center School of Life SciencesGuangzhou UniversityGuangzhouGuangdong ProvinceChina

Glutamatergic projection neurons generate sophisticated excitatory circuits to integrate and transmit information among different cortical areas,and between the neocortex and other regions of the brain and spinal *** development of cortical projection neurons is regulated by certain essential events such as neural fate determination,proliferation,specification,differentiation,migration,survival,axonogenesis,and *** processes are precisely regulated in a tempo-spatial manner by intrinsic factors,extrinsic signals,and neural *** generation of correct subtypes and precise connections of projection neurons is imperative not only to support the basic cortical functions(such as sensory information integration,motor coordination,and cognition)but also to prevent the onset and progression of neurodevelopmental disorders(such as intellectual disability,autism spectrum disorders,anxiety,and depression).This review mainly focuses on the recent progress of transcriptional regulations on the development and diversity of neocortical projection neurons and the clinical relevance of the failure of transcriptional modulations.

关键词： autism spectrum disorders cognition differentiation excitatory circuits intellectual disability neocortex neurodevelopmental disorders projection neuron specification transcriptional regulation

Explosion resistance performance of reinforced concrete box girder coated with polyurea:Model test and numerical simulation

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2024年第3期33卷 1-18页

作者： Guangpan Zhou rong wang Mingyang wang Jianguo Ding Yuye Zhang School of Science Nanjing University of Science and TechnologyNanjing 210094JiangsuChina School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing 210094JiangsuChina State Key Laboratory of Explosion and Impact and Disaster Prevention and Mitigation Army Engineering University of PLANanjing 210007JiangsuChina

To study the anti-explosion protection effect of polyurea coating on reinforced concrete box girder,two segmental girder specimens were made at a scale of 1:3,numbered as G(without polyurea coating)and PCG(with polyurea coating).The failure characteristics and dynamic responses of the specimens were compared through conducting explosion *** reliability of the numerical simulation using LS-DYNA software was verified by the test *** effects of different scaled distances,reinforcement ratios,concrete strengths,coating thicknesses and ranges of polyurea were *** results show that the polyurea coating can effectively enhance the anti-explosion performance of the *** top plate of middle chamber in specimen G forms an elliptical penetrating hole,while that in specimen PCG only shows a very slight local *** peak vertical displacement and residual displacement of PCG decrease by 74.8% and 73.7%,respectively,compared with those of specimen *** the TNT explosion with small equivalent,the polyurea coating has a more significant protective effect on reducing the size of *** the increase of TNT equivalent,the protective effect of polyurea on reducing girder displacement becomes more *** optimal reinforcement ratio,concrete strength,thickness and range of polyurea coating were also drawn.

关键词： Explosive load Explosion resistance performance Model test Polyurea Concrete box girder Numerical simulation

Acute suppurative terminal cholangitis:Clinical characteristics of a new subtype of acute cholangitis

在线全文

学校读者我要写书评

暂无评论

Hepatobiliary & Pancreatic Diseases International 2024年第3期23卷 293-299页

作者： rong-Tao Zhu Ye Li Chi-Xian Zhang Wei-Jie wang Ruo-Peng Liang Jian Li kai Bai Yu-Ling Sun Department of Hepatobiliary and Pancreatic Surgery the First Affiliated Hospital of Zhengzhou UniversityZhengzhou 450052China Zhengzhou Key Laboratory of Hepatobiliary and Pancreatic Diseases Zhengzhou 450052China Institute of Hepatobiliary and Pancreatic Diseases Zhengzhou UniversityZhengzhou 450052China Department of Pathology the First Affiliated Hospital of Zhengzhou UniversityZhengzhou 450052China

Background:Acute suppurative terminal cholangitis(ASTC)is rarer than acute obstructive cholangitis and is not well *** explore this subtype of acute cholangitis,we described our clinical experience with ***:We performed a retrospective review of patients with ASTC admitted to our center from September 2014 to August *** analyzed their clinical characteristics,including etiology,clinical manifestations,imaging features,treatment and ***:A total of 32 ASTC patients were included in the *** majority of the patients had a history of biliary operations,and clinical manifestations were occult and *** positive rate of bacterial culture was 46.9%.All the patients had typical imaging features on computed tomography and magnetic resonance *** with effective antibiotics was provided as soon as diagnosis was *** treatment,most patients had a good *** levels of total bilirubin,aspartate aminotransferase,procalcitonin and gamma-glutamyltransferase were the characteristics of critically ill patients and were associated with relatively poor ***:Our results demonstrated that ASTC should be recognized as a new subtype of acute cholangitis,and that earlier diagnosis and more personalized treatments are needed.

关键词： Acute suppurative terminal cholangitis Acute cholangitis Gram-negative bacterial infections Diagnosis Treatment