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Chinese Journal of Polymer Science 2015年第7期33卷 1000-1008页

作者： Yan-hu Xue shu-qin Bo 姬相玲 State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of Sciences University of Chinese Academy of Sciences

A series of copolymers of ethylene with 1-hexene synthesized using a metallocene catalyst are selected and mixed. The blend is fractionated via preparative temperature rising elution fractionation（P-TREF）. All fractions are characterized via high-temperature gel permeation chromatography（GPC）, 13 C nuclear magnetic resonance spectroscopy（13C-NMR）, and differential scanning calorimetry（DSC）. The changes in the DSC melting peak temperatures of the fractions from P-TREF as a function of elution temperature are almost linear, thereby providing a reference through which the elution temperature of TREF experiments could be selected. Moreover, the standard calibration curve（ethylene/1-hexene） of P-TREF is established, which relates to the degree of short-chain branching of the fractions. The standard calibration curve of P-TREF is beneficial to study on the complicated branching structure of polyethylene. A convenient method for selecting the fractionation temperature for TREF experiments is elaborated. The polyethylene sample is fractionated via successive self-nucleation and annealing（SSA） thermal fractionation. A multiple-melting endotherm is obtained through the final DSC heating scan for the sample after SSA thermal fractionation. A series of fractionation temperatures are then selected through the relationship between the DSC melting peak temperature and TREF elution temperature.

关键词： TREF Calibration curve Fractionation temperature SSA Polyethylene

Reactive scheduling of multiple EOSs under cloud uncertainties:model and algorithms

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Journal of Systems Engineering and Electronics 2021年第1期32卷 163-177页

作者： WANG Jianjiang hu Xuejun he Chuan College of Systems Engineering National University of Defense TechnologyChangsha 410073China Business School Hunan UniversityChangsha 410082China Beijing Institute of Tracking and Telecommunications Technology Beijing 100094China

Most earth observation satellites(EOSs)are low-orbit satellites equipped with optical sensors that cannot see through ***,cloud coverage,high dynamics,and cloud uncertainties are important issues in the scheduling of *** proactive-reactive scheduling framework has been proven to be effective and efficient for the uncertain scheduling problem and has been extensively *** studies have been conducted on methods for the proactive scheduling of EOSs,including expectation,chance-constrained,and robust optimization models and the relevant solution *** study focuses on the reactive scheduling of EOSs under cloud ***,using an example,we describe the reactive scheduling problem in detail,clarifying its significance and key *** the two key objectives of observation profits and scheduling stability,we construct a multi-objective optimization mathematical ***,we obtain the possible disruptions of EOS scheduling during execution under cloud uncertainties,adopting an event-driven policy for the reactive *** the different disruptions,different reactive scheduling algorithms are ***,numerous simulation experiments are conducted to verify the feasibility and effectiveness of the proposed reactive scheduling *** experimental results show that the reactive scheduling algorithms can both improve observation profits and reduce system perturbations.

关键词： earth observation satellite(EOS) uncertainty of clouds reactive scheduling multi-objective optimization event-driven heuristic

Formation Tracking for Nonlinear Multi-agent Systems with Input and Output Quantization via Adaptive Output Feedback Control

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Journal of Systems Science & Complexity 2020年第2期33卷 401-425页

作者： hu Jinglin SUN Xiuxia he Lei Air Force Engineering University Xi'an 710038China System Engineering Research Institute Air Force Research InstituteBeijing 100070China

Signal quantization can reduce communication burden in multi-agent systems,whereas it brings control challenge to multi-agent formation *** paper studies the output feedback control problem for formation tracking of multi-agent systems with both quantized input and *** agents are described by a nonlinear dynamic model with unknown parameters and immeasurable *** estimate immeasurable states and solve the uncertainties,state observers are developed by using dynamic high-gain *** proper parameter designs,an output feedback quantized controller is established based on quantized output signals,and the quantization effect on the control system is *** analysis proves that,with the proposed control scheme,multi-agent systems can track the reference trajectory while forming and maintaining the desired formation *** addition,all the signals in the closed-loop systems are ***,the numerical simulation and practical experiment are provided to verify the theoretical analysis.

关键词： Adaptive output feedback formation tracking hysteretic quantizer multi-agent system

A Deep Generative Model with Multiscale Features Enabled Industrial Internet of Things for Intelligent Fault Diagnosis of Bearings

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Research 2023年第3期2023卷 57-68页

作者： he-xuan hu Yicheng Cai Qiang hu Ye Zhang Key Laboratory of Water Big Data Technology of Ministry of Water Resources Hohai UniversityNanjing 211100P.R.China College of Computer and Information Hohai UniversityNanjing 211100P.R.China

Effective condition monitoring and fault diagnosis of bearings can not only maximize the life of rolling bearings and prevent unexpected shutdowns caused by equipment failures but also eliminate unnecessary costs and waste caused by excessive ***,the existing deep-learning-based bearing fault diagnosis models have the following *** of all,these models have a large demand for fault ***,the previous models only consider that single-scale features are generally less effective in diagnosing bearing ***,we designed a bearing fault data collection platform based on the Industrial Internet of Things,which is used to collect bearing status data from sensors in real time and feed it back into the diagnostic *** the basis of this platform,we propose a bearing fault diagnosis model based on deep generative models with multiscale features(DGMMFs)to solve the above *** DGMMF model is a multiclassification model,which can directly output the abnormal type of the ***,the DGMMF model uses 4 different variational autoencoder models to augment the bearing data and integrates features of different *** with single-scale features,these multiscale features contain more information and can perform ***,we conducted a large number of related experiments on the real bearing fault datasets and verified the effectiveness of the DGMMF model using multiple evaluation *** DGMMF model has achieved the highest value under all metrics,among which the value of precision is 0.926,the value of recall is 0.924,the value of accuracy is 0.926,and the value of F1 score is 0.925.

关键词： fault bearings diagnosis

Microstructure and Hardness of T250 Maraging Steel in heat Affected Zone

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Journal of Iron and Steel Research International 2009年第1期16卷 87-91页

作者： MO De-feng hu Zheng-fei CheN shu-juan WANG Chun-xu he Guo-qiu School of Material Science and Engineering Tongji University Shanghai 200092 China Central Iron and Steel Research Institute Beijing 100081 China

Electron-beam （EB） welding was used in T250 maraging steel, microstructures of both base material and heat affected zone （HAZ） were investigated by optical microscopy （OM）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）, and microhardness was tested. The results showed that during EB welding, the HAZ of T250 maraging steel exhibited a continuous gradient structure. The microstrueture of the entire HAZ, from fusion line, could be divided into four zones： fusion zone, overheated zone, transition zone, and hardened zone. The microhardness showed a distinct regularity in each area. The softest region was the fusion zone, whereas the hardest was the hardened zone. In the overheated zone, the hardness increased as the grain size decreased. Furthermore, in the transition zone, the hardness level dropped noticeably. The peak temperature during the thermal cycle had a great influence on the formation of reverted austenite and dissolution of the precipitated particles, which contributed a lot to the microstructure and hardness of this material.

关键词： T250 maraging steel electron-beam weld microstructure microhardness

Single-valued definition of the multivalued function for borehole acoustic waves in transversely isotropic formations

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Science China(Physics,Mechanics & Astronomy) 2010年第8期53卷 1419-1426页

作者： he Xiao hu hengShan Department of Astronautics and Mechanics Harbin Institute of TechnologyHarbin 150001China

It is useful to extract all components, including compressional, shear, and guided waves, from the full waveforms when we investigate the acoustic log data. The component waves can be simulated by calculating the contributions from poles and branch points of the borehole acoustic function according to Cauchy’s theorem. For such an algorithm to be implemented, the multivalued function for the borehole wave field in the frequency-axial-wavenumber domain has to be rendered single-valued first. Assuming that the borehole axis is parallel to the symmetry axis of transverse isotropy, this paper derives the branch points of the borehole acoustic function. We discover that the number and the locations of those branch points are determined by the relation among the formation parameters c33, c44, ε, and δ. Thus the single-valued definitions in the acoustic-wave computation are sorted into two different cases. After building the Riemann surface related to each radial wavenumber, we give the single-valued definition of the borehole acoustic function inside and on the integration contour based on the radiation condition. In a formation with δ > ε + c44/2c33, if we choose the integration contour and the single-valued definition of the acoustic function in the way used in isotropic cases, the simulation results of component waves will be wrong.

关键词： anisotropy acoustic logging elastic wave Riemann sheet

A Portable Fall Detection and Alerting System Based on k-NN Algorithm and Remote Medicine

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China Communications 2015年第4期12卷 23-31页

作者： he Jian hu Chen School of Software Engineering Beijing University of Technology

This paper presents information on a portable fall detection and alerting system mainly consisting of a custom vest and a mobile smart phone. A wearable motion detection sensor integrated with tri-axial accelerometer, gyroscope and Bluetooth is built into a custom vest worn by elderly. The vest can capture the reluctant acceleration and angular velocity about the activities of daily living(ADLs) of elderly in real time. The data via Bluetooth is then sent to a mobile smart phone running a fall detection program based on k-NN algorithm. When a fall occurs the phone can alert a family member or health care center through a call or emergent text message using a built in Global Positioning System. The experimental results show that the system discriminates falls from ADLs with a sensitivity of 95%, and a specificity of 96.67%. This system can provide remote monitoring and timely help for the elderly.

关键词： telemedicine fall detection k-NN smart phone bluetooth

Near-perfect replication on amorphous alloys through active force modulation based on machine learning/neural network parameter prediction

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Science China(Physics,Mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 181-191页

作者： Senkuan Meng Zheng Wang Ruisong Zhu Ruijie Liu Jiang Ma Lina hu Weihua Wang Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education) School of Materials Science and Engineering Shandong University College of Mechatronics and Control Engineering Shenzhen University Songshan Lake Materials Laboratory Institute of Physics Chinese Academy of Sciences

As a microforming technique, micro/nano-structural replication possesses advantages of high precision and efficiency. With the remarkable superplasticity in the supercooled liquid region, amorphous alloys or metallic glasses(MGs) are regarded as ideal materials for miniature fabrication. However, due to the intrinsic metastable nature of supercooled liquids, the design of imprinting processes for MGs poses a challenge. In the past, process parameters have largely relied on trial-and-error *** this work, a low-frequency active force modulation system is employed to apply a stable, precise, and real-time feedback stress field for imprinting of MG samples. Low-frequency vibrations can facilitate the filling of microstructures on the template surface by reducing the effective viscosity of the supercooled liquid. With the dataset composed of orthogonal experiments, a machine learning strategy based on back-propagation(BP) neural networks was utilized to construct a 3D parameter space for temperature, stress, and time, and to predict the corresponding filling ratio. Furthermore, the optimal combination of imprinting process parameters was identified, and its filling ratio was experimentally validated to reach as high as 0.94. The near-perfect replication of microstructures confirms the superiority of the active force modulation system and the data-driven strategy of machine learning-assisted parameter design. At the same time, this one-step microforming process provides a new approach to addressing the accuracy-cost trade-off dilemma in precision manufacturing.

关键词： metallic glass amorphous alloy microforming imprinting machine learning

On n-universal quadratic forms over dyadic local fields

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Science China Mathematics 2024年第7期67卷 1481-1506页

作者： Zilong he Yong hu School of Computer Science and Technology Dongguan University of TechnologyDongguan523808China Department of Mathematics Southern University of Science and TechnologyShenzhen518055China

Let n≥2 be an integer. We give necessary and sufficient conditions for an integral quadratic form over dyadic local fields to be n-universal by using invariants from Beli's theory of bases of norm ***, we provide a minimal set for testing n-universal quadratic forms over dyadic local fields, as an analogue of Bhargava and Hanke's 290-theorem(or Conway and Schneeberger's 15-theorem) on universal quadratic forms with integer coefficients.

关键词： integral quadratic forms n-universal quadratic forms dyadic fields 290-theorem

Effect of Seasonality on Distribution of Macroalgae in a Stream System(Xin'an Spring) in Shanxi Province,North China

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Journal of Integrative Plant Biology 2006年第8期48卷 889-896页

作者： Bian-Fang hu shu-Lian Xie School of Life Science and Technology Shanxi University Taiyuan 030006 China

A survey of the seasonal distribution of macroalgae in a stream system in Shanxi Province, north China, was undertaken from July 2004 to April 2005. The relative abundance and percentage cover of macroalgae, and several environmental factors were monitored along a 20-m stretch at each of four sites, at intervals of approximately three months （one sampling per season）. Several stream conditions were relatively constant over the sampling period （pH, maximum width and maximum depth）, whereas others exhibited a distinct seasonal pattern （water temperature and specific conductance）, and some fluctuated with no discernable seasonal pattern （current velocity and dissolved oxygen）. Forty-two species of macroalgae were found, with a predominance of Chlorophyta （26 species, 61.9%）. Rhodophyts and Charophyta represented the smallest proportion （1 species each, 2.38%）. Six macroalgae species were the most widespread, occurring in all four sampling sites. Twelve species were found at only one site each. In terms of seasonality, eight species occurred throughout the year, whereas 16 species were found in only one season each. The macroalgal community at Xin＇an Spring was species rich relative to other streams. Species richness per sampling site was negatively correlated with pH. Principal component analysis revealed that no single variable had much influence on the macroalgal seasonal dynamics. We calculated Sorensen similarity indices to compare our study with other continent-wide surveys of stream macroalgae, but the similarity indices were all very low. This study also shows that macroalgae in different locations have significant reproductive isolation.

关键词： China distribution environmental factors seasonality stream macroalgae.