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Motion-pressure coupled control and simulation of long-endurance capability for multicapsule stratospheric airships

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Chinese Journal of Aeronautics 2024年第6期37卷 137-150页

作者： Zhiguang SHI Wei HUO Zongyu ZUO school of Automation Science and Electrical Engineering Beihang UniversityBeijing 100191China Beijing Near Space Airship Technology development Co. LtdBeijing 100070China

The current study focuses on the motion-pressure coupled control for a multicapsule stratospheric airship and transforms the path-tracking and heading-hold control of airships into guidance tracking with a time-varying weighted sum of longitudinal and lateral velocities by the definition of compound ***,an improved nonlinear predictive control method is provided to reduce the control energy consumption by the rolling optimization of controller parameters based on finite time intervals,ensuring infinite-time path-tracking ***,combined with the proposed cyclic regulation process of safe pressure between internal and external capsules,this study can fully reflect the force-thermal coupled rule of airships under the actions of atmospheric environment and maneuvering force,while evaluating the long-endurance capability of airships under the conditions of safe superheating and *** effectiveness of the motionpressure coupled controller was verified through numerical simulations,which can overcome the influence of environmental wind and achieve a tracking effect for the desired cruise path and compound *** airspeed provided during the cyclic circadian time caused the maximum superheating of the helium controlled within 30*** helium in the internal and external capsules achieved circadian *** equivalent micropore diameter of the capsule of 5 mm can achieve 55 days of long-endurance *** controller satisfies the requirements of cruise-flight application modes for multicapsule stratospheric airships with important engineering value.

关键词： Compound speed Nonlinear predictive control Cyclic pressure regulation Long-endurance capability Stratospheric airship

Secure Tracking Control via Fixed-Time Convergent Reinforcement Learning for a UAV CPS

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IEEE/CAA Journal of Automatica Sinica 2024年第7期11卷 1699-1701页

作者： Zhenyu Gong Feisheng Yang the school of Automation Northwestern Polytechnical UniversityXi’an 710129 the Research&development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen 518063China

Dear Editor,This letter is concerned with the secure tracking control problem in the unmanned aerial vehicle(UAV) system by fixed-time convergent reinforcement learning(RL). By virtue of the zero-sum game,the false da... 详细信息

关键词： Secure Fixed false

Epidemiological Surveillance: Genetic Diversity of Rotavirus Group A in the Pearl River Delta, Guangdong, China in 2019

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Biomedical and Environmental Sciences 2024年第3期37卷 278-293页

作者： JIANG Jie Ying LIANG Dan WANG Li XIAO Yun LIANG Yu Feng KE Bi Xia SU Juan XIAO Hong WANG Tao ZOU Min LI Hong Jian KE Chang Wen school of public Health Shantou UniversityShantou 515063GuangdongChina Guangdong Provincial Center for Disease Control and Prevention Guangdong Workstation for Emerging Infectious Disease Control and PreventionGuangzhou 511430GuangdongChina Guangdong Provincial Key Laboratory of Virology Institute of Medical MicrobiologyJinan UniversityGuangzhou 510632GuangdongChina school of public Health Sun Yat-sen UniversityGuangzhou 510275GuangdongChina school of public Health Southern Medical UniversityGuangzhou 510515GuangdongChina Shantou University Medical College Shantou 515041GuangdongChina

Objective This study aimed to understand the epidemic status and phylogenetic relationships of rotavirus group A(RVA)in the Pearl River Delta region of Guangdong Province,*** This study included individuals aged 28 days–85 years.A total of 706 stool samples from patients with acute gastroenteritis collected between January 2019 and January 2020 were analyzed for 17 causative pathogens,including RVA,using a Gastrointestinal Pathogen Panel,followed by genotyping,virus isolation,and complete sequencing to assess the genetic diversity of *** The overall RVA infection rate was 14.59%(103/706),with an irregular epidemiological *** proportion of co-infection with RVA and other pathogens was 39.81%(41/103).Acute gastroenteritis is highly prevalent in young children aged 0–1 year,and RVA is the key pathogen circulating in patients 6–10 months of age with diarrhea.G9P[8](58.25%,60/103)was found to be the predominant genotype in the RVA strains,and the 41 RVA-positive strains that were successfully sequenced belonged to three different RVA genotypes in the phylogenetic *** analysis showed that gene reassortment events,selection pressure,codon usage bias,gene polymorphism,and post-translational modifications(PTMs)occurred in the G9P[8]and G3P[8]*** This study provides molecular evidence of RVA prevalence in the Pearl River Delta region of China,further enriching the existing information on its genetics and evolutionary characteristics and suggesting the emergence of genetic *** the surveillance of genotypic changes and gene reassortment in RVA strains is essential for further research and a better understanding of strain variations for further vaccine development.

关键词： Infectious diarrheal disease Rotavirus Phylogenetic analysis Gene rearrangement Codon usage bias Genetic diversity

Promoting higher-valent pediatric combination vaccines in China: challenges and recommendations for action

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Infectious Diseases of Poverty 2024年第1期13卷 74-84页

作者： Jiuling Li Shu Chen dwin Asturias Shenglan Tang Fuqiang Cui Global Health Research Center Duke Kunshan UniversityKunshanJiangsuChina ARC Centre of Excellence in Population Ageing Research(CEPAR) Universityof New SouthWalesSydneyAustralia school of Risk and Actuarial Studies University of New South WalesSydneyAustralia Department of Pediatrics University of Colorado School of MedicineAuroraCOUSA Center for Global Health Colorado School of Public HealthAuroraCOUSA Department of Epidemiology Colorado School of Public HealthAuroraCOUSA Duke Global Health Institute Duke UniversityDurhamNCUSA SingHealth Duke-NUS Global Health Institute Duke-NUSSingaporeSingapore Department of Laboratorial Science and Technology School of Public HealthPeking UniversityBeijingChina Vaccine Research Center School of Public HealthPeking UniversityBeijingChina

Many countries have adopted higher-valent pediatric combination vaccines to simplify vaccination schedules and minimize health expenditures and social ***,China is conservative in the use of pediatric combina-tion *** reviewing and synthesizing quantitative and qualitative data,in this commentary we identify gaps and challenges to combination vaccine use and make recommendations for promoting use of higher-valent pediatric combination vaccines in *** are in four dimensions:(1)legislation and regulation,(2)immunization schedule design,(3)vaccine awareness and price,and(4)research and development *** optimize the use of combination vaccines to reduce vaccine-preventable disease burden,we make recommendations that address key challenges:(1)develop policies and regulations to strengthen enforcement of the Vaccine Administration Law and remove regulatory hurdles that hinder combination vaccine research and development,(2)establish an evi-dence-informed policy-making mechanism for combination vaccines,(3)resolve immunization schedule conflicts between monovalent and combination vaccines,and(4)implement effective interventions to increase vaccine awareness and reduce price.

关键词： Combination vaccine National immunization program Childhood immunization Vaccine-preventable disease

Lightweight Multi-Resolution Network for Human Pose Estimation

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Computer Modeling in Engineering & Sciences 2024年第3期138卷 2239-2255页

作者： Pengxin Li Rong Wang Wenjing Zhang Yinuo Liu Chenyue Xu school of Information and Cyber Security People Public Security University of ChinaBeijing100038China Key Laboratory of Security Prevention Technology and Risk Assessment of Ministry of public Security Beijing100038China

Human pose estimation aims to localize the body joints from image or video *** the development of deeplearning,pose estimation has become a hot research topic in the field of computer *** recent years,humanpose estimation has achieved great success in multiple fields such as animation and ***,to obtainaccurate positioning results,existing methods may suffer from large model sizes,a high number of parameters,and increased complexity,leading to high computing *** this paper,we propose a new lightweight featureencoder to construct a high-resolution network that reduces the number of parameters and lowers the *** also introduced a semantic enhancement module that improves global feature extraction and networkperformance by combining channel and spatial ***,we propose a dense connected spatialpyramid pooling module to compensate for the decrease in image resolution and information loss in the ***,ourmethod effectively reduces the number of parameters and complexitywhile ensuring high *** experiments show that our method achieves a competitive performance while dramatically reducing thenumber of parameters,and operational ***,our method can obtain 89.9%AP score on MPIIVAL,while the number of parameters and the complexity of operations were reduced by 41%and 36%,respectively.

关键词： Lightweight human pose estimation keypoint detection high resolution network

Nutrition impacts of non-solid cooking fuel adoption on under-five children in developing countries

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Journal of Integrative Agriculture 2024年第2期23卷 397-413页

作者： Yalin Tang Yuhe Guo Gang Xie Chengfang Liu China Center for Agricultural policy School of Advanced Agricultural SciencesPeking UniversityBeijing 100871China Agricultural Information Institute Chinese Academy of Agricultural SciencesBeijing 100081China

This paper examines the nutrition impacts of using non-solid cooking fuel on under-five children in developing *** draw on data from more than 1.12 million children in 62 developing countries from the Demographic and Health Surveys(DHS).Results from both fixed effects(FE)and instrumental variable(IV)estimates show that using non-solid cooking fuel significantly improves the nutrition outcomes of under-five *** with their peers from households mainly using solid fuel,children from households mainly using non-solid fuel exhibit a lower probability of experiencing stunting(by 5.9 percentage points)and being underweight(by 1.2 percentage points).Our further investigation provides evidence for several underlying mechanisms,such as improved indoor air quality,induced reduction in children’s respiratory symptoms,benefits on maternal health,and reduction in maternal time spent on fuel collection or *** analyses suggest that the nutrition benefits of using non-solid cooking fuel are more prominent among boys,children above three years old,and those from households of lower socioeconomic status,rural areas,and Southeast Asia.

关键词： non-solid cooking fuel nutrition benefits under-five children developing countries

A semi-analytical model for coupled flow in stress-sensitive multi-scale shale reservoirs with fractal characteristics

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Petroleum Science 2024年第1期21卷 327-342页

作者： Qian Zhang Wen-Dong Wang Yu-Liang Su Wei Chen Zheng-Dong Lei Lei Li Yong-Mao Hao Key Laboratory of Unconventional Oil&Gas development(China University of Petroleum(East China)) Ministry of EducationQingdao266580ShandongChina school of Petroleum Engineering China University of Petroleum(East China)Qingdao266580ShandongChina Shale Oil development Branch Changqing Oilfield CompanyPetroChinaQingyang745708GansuChina PetroChina Research Institute of Petroleum Exploration&development Beijing100083China

A large number of nanopores and complex fracture structures in shale reservoirs results in multi-scale flow of oil. With the development of shale oil reservoirs, the permeability of multi-scale media undergoes changes due to stress sensitivity, which plays a crucial role in controlling pressure propagation and oil flow. This paper proposes a multi-scale coupled flow mathematical model of matrix nanopores, induced fractures, and hydraulic fractures. In this model, the micro-scale effects of shale oil flow in fractal nanopores, fractal induced fracture network, and stress sensitivity of multi-scale media are considered. We solved the model iteratively using Pedrosa transform, semi-analytic Segmented Bessel function, Laplace transform. The results of this model exhibit good agreement with the numerical solution and field production data, confirming the high accuracy of the model. As well, the influence of stress sensitivity on permeability, pressure and production is analyzed. It is shown that the permeability and production decrease significantly when induced fractures are weakly supported. Closed induced fractures can inhibit interporosity flow in the stimulated reservoir volume (SRV). It has been shown in sensitivity analysis that hydraulic fractures are beneficial to early production, and induced fractures in SRV are beneficial to middle production. The model can characterize multi-scale flow characteristics of shale oil, providing theoretical guidance for rapid productivity evaluation.

关键词： Multi-scale coupled flow Stress sensitivity Shale oil Micro-scale effect Fractal theory

Evolution and Determinants of Population Agglomeration in Less Developed Metropolitan Areas:A Case Study of the Taiyuan Metropolitan Area,China

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Chinese Geographical Science 2024年第4期34卷 739-751页

作者： QIN Zhiqin LIANG Ye AN Shuwei DOU Yongjing school of Economics and Management Shanxi UniversityTaiyuan 030031China school of Urban Economics and public Affairs Capital University of Economics and BusinessBeijing 100070China school of Geography Science Taiyuan Normal UniversityJinzhong 030619China

It is of importance to enhance the urban areas'capacity for population aggregation in underdeveloped regions,aiming to rectify the imbalanced and insufficient pattern of economic development in *** the Taiyuan Metropolitan Area(TMA)in central China as a case study,this paper examines the evolutionary process and characteristics of population agglomeration from 2000 to 2020,and identifies factors associated with agglomeration and their spatial *** findings indicated that:1)against the background of sustained population shrinkage in the provincial area,the TMA showed a demographic trend of steady increase,albeit with a decelerated growth *** the metropolitan area,urban population size continued to grow rapidly,whereas the rural areas endured sustained *** in city size continued to widen,and the polarization of concentrated population in the core cities kept increasing.2)Agglomerations in both secondary and service industries had significant positive effects on local population agglomeration,with the former effect being *** economic development,government fiscal expenditure,and financial advancement all contributed to facilitating local population *** a spatial spillover perspective,service agglomeration and financial development promoted population agglomeration in surrounding ***,fiscal expenditure inhibited such *** for industrial agglomeration and regional economic development,their spatial spillover effects were *** results obtained reveal several policy implications aimed at enhancing the population agglomeration capacity of the metropolitan area in underdeveloped regions during the new era.

关键词： population agglomeration population shrinkage spatial spillover effects Taiyuan Metropolitan Area(TMA) China

In situ formed Mg(BH_(4))_(2) for improving hydrolysis properties of MgH_(2)

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Journal of Magnesium and Alloys 2024年第3期12卷 1204-1214页

作者： Yongyang Zhu Mili Liu liming Zeng Yin Wang Daifeng Wu Rui Li Qing Zhou Renheng Tang Fangming Xiao Institute of Resources Utilization and Rare Earth development Guangdong Provincial Key Laboratory of Rare Earth Development and ApplicationGuangdong Academy of SciencesGuangzhou 510650China school of Materials Science and Engineering Guangdong Provincial Key Laboratory of Advanced Energy Storage MaterialsSouth China University of TechnologyGuangzhou 510641China

The hydrolysis of MgH_(2) delivers high hydrogen capacity(15.2 wt%),which is very attractive for real-time hydrogen ***,the formation of a surface passivation Mg(OH)_(2) layer and the large excess of H_(2)O required to ensure complete hydrolysis are two key challenges for the MgH_(2) hydrolysis ***,a low-cost method is reported to synthesize MgH_(2)@Mg(BH_(4))_(2) composite via ball-milling MgH_(2) with cheap and widely available B_(2)O_(3)(or B(OH)_(3)).By adding small amounts of B_(2)O_(3),the in-situ formed Mg(BH_(4))_(2) could significantly promote the hydrolysis of MgH_(2).In particular,the MgH_(2)–10 wt%B_(2)O_(3) composite releases 1330.7 mL·g^(−1) H_(2)(close to 80%theoretical hydrogen generation H_(2))in H_(2)O and 1520.4 mL·g^(−1) H_(2)(about 95%)in 0.5 M MgCl_(2) in 60 min at 26℃ with hydrolysis rate of 736.9 mL·g^(−1)·min^(−1) and 960.9 mL·g^(−1)·min^(−1) H_(2) during the first minute of the hydrolysis,*** addition,the MgCl_(2) solution allows repeated use by filtering and exhibits high cycle stability(20 cycles),therefore leading to much reduced capacity loss caused by the excess H_(2)*** show that by introducing B_(2)O_(3) and recycling the 0.5 M MgCl_(2) solution,the system hydrogen capacity can approach 5.9 wt%,providing a promising hydrogen generation scheme to supply hydrogen to the fuel cells.

关键词： Hydrolysis MgH_(2) Mg(BH_(4))_(2) Hydrogen generation B_(2)O_(3) MgCl_(2)