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Nonstationary channel model of reentry plasma sheath for spacecraft: Overview, parameter estimation, and perspective

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Chinese Journal of Aeronautics 2024年第10期37卷 26-49页

作者： Lei SHI Zongyuan liu Weimin BAO Bo YAO Yifan WANG Xiaoping li Yanming liu Fangyan li School of Aerospace Science and Technology Xidian UniversityXi’an 710126China Key Laboratory of Equipment Efficiency in Extreme Environment Ministry of EducationXi’an 710126China China Aerospace Science and Technology Corporation Beijing 100048China

The Tracking,Telemetering,and Command(TT&C)communication of spacecraft faces severe limitations during *** Electromagnetic(EM)propagation channel is influenced by changes in the flight state and fluid *** addition to the high-speed spatial channel,the Plasma Sheath Channel(PSC),which covers the surface of spacecraft,exhibits unique nonstationary and highly dynamic time-varying *** absence of a channel model for the reentry process of spacecraft negatively impacts the quality evaluation and system design of TT&C *** paper summarizes the methods for nonstationary PSC modeling,involving calculation methods for attenuation and phase shift in the channel,as well as a multistate nonstationary channel statistical model based on a hidden Markov ***,the correlation between amplitude variation and phase variation with electron density is *** paper also provides statistical characteristics of the channel and channel parameters at typical frequencies in the S/C/X/Ka *** findings serve as a reference for the design and evaluation of TT&C communication systems for reentry ***,the paper discusses the prospects of various aspects related to the channel characteristics and modeling of spacecraft PSCs in the shortwave and terahertz/laser bands,as well as the potential challenges in cross-domain spacecraft channel sensing and prediction.

关键词： Spacecraft Plasma sheaths Electromagnetic wave transmission Communication channels Channel estimation

A Correlation-Based Stochastic Model for Massive MIMO Channel

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China Communications 2024年第1期21卷 175-187页

作者： Yang liu Gang li Chengxiang Wang National Mobile Communications Research Laboratory School of Information Science and EngineeringSoutheast UniversityNanjing 211189China School of Internet of Things Engineering Jiangnan UniversityWuxi 214122China Pervasive Communication Research Center Purple Mountain LaboratoriesNanjing 211111China

In this paper,the channel impulse response matrix(CIRM)can be expressed as a sum of couplings between the steering vectors at the base station(BS)and the eigenbases at the mobile station(MS).Nakagami distribution was used to describe the fading of the coupling between the steering vectors and the *** measurements were carried out to evaluate the performance of this proposed ***,the physical implications of this model were illustrated and the capacities are *** addition,the azimuthal power spectrum(APS)of several models was ***,the channel hardening effect was simulated and *** showed that the proposed model provides a better fit to the measured results than the other CBSM,i.e.,Weichselberger ***,the proposed model can provide better tradeoff between accuracy and complexity in channel *** CIRM model can be used for massive MIMO design in the future communication system design.

关键词： CBSM channel capacity channel hardening channel modeling massive MIMO

Hybrid ionic thermoelectric and photocatalytic materials(i-TEPC):a new choice for energy harvesting

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Science China Chemistry 2024年第7期67卷 2127-2129页

作者： Qikai li Mao Yu Weishu liu Department of Materials Science and Engineering Southern University of Science and TechnologyShenzhen 518055China

Ionic thermoelectric(i-TE)material is a kind of new functional material that can convert heat energy into electric energy,which is of great significance for renewable energy technologies and sustainable development[1].The fundamental constitution of i-TE material mainly comprises an electrolyte matrix,ion providers and redox pairs.

关键词： energy harvesting convert

Bile acids and coronavirus disease 2.19

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Acta Pharmaceutica Sinica B 2024年第5期14卷 1939-1950页

作者： Xiaoru Huang Xuening liu Zijian li Department of Pharmacy Peking University Third HospitalBeijing 100191China Department of Pharmaceutical Management and Clinical Pharmacy College of PharmacyPeking UniversityBeijing 100191China Department of Cardiology and Institute of Vascular Medicine Peking University Third HospitalBeijing Key Laboratory of Cardiovascular Receptors ResearchKey Laboratory of Cardiovascular Molecular Biology and Regulatory PeptidesMinistry of HealthState Key Laboratory of Vascular Homeostasis and RemodelingPeking UniversityBeijing 100191China

The coronavirus disease 2.19(COVID-19)pandemic,caused by severe acute respiratory syndrome coronavirus 2.SARS-CoV-2.,has been significantly ***,long-term health effects and prevention strategy remain ***,it is essential to explore the pathophysiological mechanisms and intervention for SARS-CoV-2.*** research indicates a link between COVID-19 and bile acids,traditionally known for facilitating dietary fat *** bile acid ursodeoxycholic acid potentially protects against SARS-CoV-2.infection by inhibiting the farnesoid X receptor,a bile acid nuclear *** activation of G-protein-coupled bile acid receptor,another membrane receptor for bile acids,has also been found to regulate the expression of angiotensin-converting enzyme 2.the receptor through which the virus enters human ***,we review the latest basic and clinical evidence linking bile acids to SARS-CoV-2.and reveal their complicated pathophysiological mechanisms.

关键词： Bile acids COVID-19 Farnesoid X receptor G-protein-coupled bile acid receptor SARS-CoV-2 Angiotensin-converting enzyme 2 Ursodeoxycholic acid Chenodeoxycholic acid

Identification of the Hammerstein nonlinear system with noisy output measurements

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Control Theory and Technology 2024年第2期22卷 203-212页

作者： Qiming Zha Feng li Ranran liu School of Electrical and Information Engineering Jiangsu University of TechnologyChangzhou213001JiangsuChina School of Automobile and Traffic Engineering Jiangsu University of TechnologyChangzhou213001JiangsuChina

In this research, we present a methodology to identify the Hammerstein nonlinear system with noisy output measurements. The Hammerstein system presented is comprised of neural fuzzy model (NFM) as its static nonlinear block and auto-regressive with extra input (ARX) model as its dynamic linear block, and a two-step procedure is accomplished using signal combination. In the first step, in the case of input–output of Gaussian signals, the correlation function-based least squares (CF-LS) technique is utilized to identify the linear block, solving the problem that the intermediate variable connecting nonlinear and linear blocks cannot be measured. In the second step, to improve the identification accuracy of the nonlinear block parameters, an improved particle swarm optimization technique is developed under input–output of random signals. The validity and accuracy of the presented scheme are verified by a numerical simulation and a practical nonlinear process, and the results illustrate that the proposed methodology can identify well the Hammerstein nonlinear system with noisy output measurements.

关键词： Hammerstein nonlinear system Signal combination Auto-regressive with extra input Improved particle swarm optimization

Phylotranscriptomic discordance is best explained by incomplete lineage sorting within Allium subgenus Cyathophora and thus hemiplasy accounts for interspecific trait transition

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Plant Diversity 2024年第1期46卷 28-38页

作者： Zengzhu Zhang Gang liu Minjie li State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems College of EcologyLanzhou UniversityLanzhou 730000GansuPR China

The transition of traits between genetically related lineages is a fascinating topic that provides clues to understanding the drivers of speciation and *** can be learned about this process from phylogeny-based trait ***,such inference is often plagued by genome-wide gene-tree discordance(GTD),mostly due to incomplete lineage sorting(ILS)and/or introgressive hybridization,especially when the genes underlying the traits appear ***,by collecting transcriptomes,whole chloroplast genomes(cpDNA),and population genetic datasets,we used the coalescent model to turn GTD into a source of information for ILS and employed hemiplasy to explain specific cases of apparent“phylogenetic discordance”between different morphological traits and probable species phylogeny in the Al{2.m *** concatenation and coalescence methods consistently showed the same phylogenetic topology for species tree inference based on single-copy genes(SCGs),as supported by the KS ***,GTD was high across the genomes of ***:~2.%e38.9%of the SCG trees were in conflict with the species *** and nuclear incongruence was also *** coalescent simulations indicated that such GTD was mainly a product of *** hemiplasy risk factor calculations supported that random fixation of ancient polymorphisms in different populations during successive speciation events along the *** phylogeny may have caused the character transition,as well as the anomalous cpDNA *** study exemplifies how phylogenetic noise can be transformed into evolutionary information for understanding character state transitions along species phylogenies.

关键词： Hemiplasy Multispecies coalescence lineage sorting Gene tree discordance Phylotranscriptomics Allium subg.Cyathophora

Influences of Graupel Microphysics on CMA-GFS Simulation of Summer Regional Precipitation

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Journal of Meteorological Research 2024年第1期38卷 27-38页

作者： Zhe li Qijun liu Zhanshan MA CMA Earth System Modeling and Prediction Centre China Meteorological Administration(CMA)Beijing 100081

The horizontal resolution of global numerical weather prediction models is continuously developing. However, due to the imperfect precipitation simulation/forecast of these models, the demand for considering riming particles in cloud microphysical schemes in these models is increasing. This study employed the latest versions of global atmospheric reanalysis data (ERA5), the satellite retrieval data of the Global Precipitation Observation Program (GPM),and station precipitation observations to explore the impacts of adding graupel to the cloud microphysical scheme in the China Meteorological Administration-Global Forecast System (CMA-GFS) on summer regional precipitation simulations in four Chinese climate zones. The results verify that the new graupel scheme can enable CMA-GFS to decently predict global graupel distribution, especially in tropical and midlatitude regions. The addition of graupel in the cloud microphysics increases the precipitation simulation in North China, while that in Southwest China is weakened and dispersed. Moreover, graupel scheme increases the precipitation simulations of almost all *** increase in light rain is obvious, and the absolute value of heavy rain is strengthened. This may be because graupel quickly melts into rain after falling out of the zero-temperature layer due to its large mass and fast falling speed, increasing surface precipitation. In summary, the addition of graupel in the cloud microphysical scheme can improve CMA-GFS’s underestimation of strong precipitation.

关键词： graupel cloud microphysical scheme precipitation China Meteorological Administration-Global Forecast System(CMA-GFS) climate zone

Non-contact and full-field online monitoring of curing temperature during the in-situ heating process based on deep learning

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Advances in Manufacturing 2024年第1期12卷 167-176页

作者： Qiang-Qiang liu Shu-Ting liu Ying-Guang {2. Xu liu Xiao-Zhong Hao College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing210016People’s Republic of China School of Mechanical and Power Engineering Nanjing Tech UniversityNanjing211816People’s Republic of China

Online monitoring of the curing temperature field is essential to improving the quality and efficiency of the manufacturing process of composite *** embedded sensor-based technologies have difficulty monitoring the full temperature field or have to introduce heterogeneous items that could have an undesired impact on the *** this paper,a non-contact,full-field monitoring method based on deep learning that predicts the internal temperature field of composite parts in real time using surface temperature measurements of auxiliary materials is *** the proposed method,an average temperature monitoring accuracy of 97%is achieved in various heating *** addition,this method also demonstrates satisfying feasibility when a stronger thermal barrier covers the *** method was experimentally validated during the self-resistance electric heating process,in which the monitoring accuracy reached 93.1%.This method can potentially be applied to automated manufacturing and process control in the composites industry.

关键词： Online monitoring Curing temperature field Deep learning(DL) In-situ heating

One-shot Face Reenactment with Dense Correspondence Estimation

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Machine Intelligence Research 2024年第5期21卷 941-953页

作者： Yunfan liu Qi li Zhenan Sun School of Artificial Intelligence University of Chinese Academy of SciencesBeijing100049China Center for Research on Intelligent Perception and Computing Institute of AutomationChinese Academy of SciencesBeijing100190China

One-shot face reenactment is a challenging task due to the identity mismatch between source and driving *** existing methods fail to completely eliminate the interference of driving subjects’identity information,which may lead to face shape distortion and undermine the realism of reenactment *** solve this problem,in this paper,we propose using a 3D morphable model(3DMM)for explicit facial semantic decomposition and identity *** of using 3D coefficients alone for reenactment control,we take advantage of the generative ability of 3DMM to render textured face *** proxies contain abundant yet compact geometric and semantic information of human faces,which enables us to compute the face motion field between source and driving images by estimating the dense *** this way,we can approximate reenactment results by warping source images according to the motion field,and a generative adversarial network(GAN)is adopted to further improve the visual quality of warping *** experiments on various datasets demonstrate the advantages of the proposed method over existing state-of-the-art benchmarks in both identity preservation and reenactment fulfillment.

关键词： Generative adversarial networks face image manipulation face image synthesis face reenactment 3D morphable model