检索结果-南通市图书馆

Joint UAV trajectory and communication design with heterogeneous multi-agent reinforcement learning

Science China(Information Sciences) 2024年第3期67卷 225-245页

作者： Xuanhan ZHOU Jun XIONG Haitao Zhao Xiaoran LIU Baoquan ren Xiaochen ZHANG Jibo WEI hao YIN College of Electronic Science and Technology National University of Defense Technology Systems Engineering Institute Academy of Military Sciences PLA

Unmanned aerial vehicles(UAVs) are recognized as effective means for delivering emergency communication services when terrestrial infrastructures are unavailable. This paper investigates a multiUAV-assisted communication system, where we jointly optimize UAVs’ trajectories, user association, and ground users(GUs)’ transmit power to maximize a defined fairness-weighted throughput metric. Owing to the dynamic nature of UAVs, this problem has to be solved in real time. However, the problem’s non-convex and combinatorial attributes pose challenges for conventional optimization-based algorithms, particularly in scenarios without central controllers. To address this issue, we propose a multi-agent deep reinforcement learning(MADRL) approach to provide distributed and online solutions. In contrast to previous MADRLbased methods considering only UAV agents, we model UAVs and GUs as heterogeneous agents sharing a common objective. Specifically, UAVs are tasked with optimizing their trajectories, while GUs are responsible for selecting a UAV for association and determining a transmit power level. To learn policies for these heterogeneous agents, we design a heterogeneous coordinated QMIX(HC-QMIX) algorithm to train local Q-networks in a centralized manner. With these well-trained local Q-networks, UAVs and GUs can make individual decisions based on their local observations. Extensive simulation results demonstrate that the proposed algorithm outperforms state-of-the-art benchmarks in terms of total throughput and system fairness.

关键词： unmanned aerial vehicle (UAV) trajectory design resource allocation multi-agent deep reinforcement learning (MADRL) heterogeneous agents

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Rapid recovery of desert shrubs is attributed to imbalance of water supply to demand after disturbance in Northwest China

引用

Ecological Processes 2024年第2期13卷 118-129页

作者： Hai Zhou Xiangyan Feng Zhibin He Qiyue yang Heng ren Wenzhi Zhao Linze Inland River Basin Research Station Chinese Ecosystem Research Network Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands Northwest Institute of Eco-Environment and Resources Chinese Academy of Sciences University of Chinese Academy of Sciences

Background Disturbance is a key driver of changes in terrestrial ecosystems, especially in water limited regions. In the desert ecosystem of Northwest China, shrubs are often foraged by camels and this causes the shrubs lost their aboveground tissues. Although the aboveground tissue could recover after the disturbance, the mechanisms of resprouts' recovery after the disturbance are still poorly understood. We investigated the morphological and physiological characteristics and root water uptake sources of resprouts and non-disturbed seedlings of four desert shrub species that were often foraged by *** The results showed that the resprouts grew rapidly after the removal of aboveground tissue. The height and aboveground biomass of resprouts reached the level of 5-year-old seedlings following a growing season. Compared to un-disturbed seedlings, higher leaf water potential, leaf hydraulic conductance and photosynthesis rate were observed in resprouts, indicating that resprouts grew rapidly after disturbance. Furthermore, we found that the root water uptake source did not change after disturbance. This indicated that the roots of resprouts kept intact water uptake capacity after disturbance, which could keep supplying sufficient water to the aboveground tissue. Due to the removal of aboveground tissue of the resprouts, the water demand of aboveground tissue decreased, which induced an imbalance of water supply from roots to demand of aboveground tissues of resprouts. This explained the improved physiological performance and rapid recovery of resprouts after *** The imbalance of water supply to demand contributes to the rapid recovery of desert shrubs after disturbance. The findings provide insight into the eco-physiological mechanism for the maintenance of desert ecosystems that are facing disturbance.

关键词： Disturbance Resprout Physiological performance Shrub Water uptake source

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

High-precision modeling of tide-induced 3-D magnetic field and analysis of geomagnetic satellite orbit requirements

引用

Science China Earth Sciences 2024年第1期67卷 165-178页

作者： Zhengyong ren Cong yang Hongbo YAO Xu TANG Jingtian TANG Keke ZHANG Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring Ministry of Education Central South UniversityChangsha 410083China Hunan Key Laboratory of Nonferrous Resources and Geological Hazards Exploration Changsha 410083China School of Geosciences and Info-Physics Central South UniversityChangsha 410083China State Key Laboratory of Lunar and Planetary Sciences Macao University of Science and TechnologyMacao 999078China

Ground-based magnetic observatories and geomagnetic satellites can observe the induced magnetic field generated by the motion of seawater containing sodium and chlorine *** the three-dimensional(3-D)spatial distribution of tide-induced magnetic fields(TIMF)is crucial for inverting the electrical conductivity structure of the oceanic *** also serves as an essential basis for designing optimal geomagnetic observatories and satellite ***,existing methods for simulating TIMF suffer from limitations in inaccurately modeling realistic coastlines,heterogeneous land and sea surface properties,and complex deep Earth structures,thereby the interpretational level of TIMF data is *** overcome this issue,we developed a tetrahedral-based finite element method for simulating TIMF,which can efficiently approximate realistic coastlines,heterogeneous land and sea surface properties,and complex deep Earth ***,we derived the boundary value problem for the seawater motion-induced electromagnetic field,which was solved using the vector finite element method based on tetrahedral ***,using the latest ocean depth and seafloor sediment layer models,we constructed a 3-D conductivity model of the Earth,which includes realistic coastlines,heterogeneous land and sea conductivity *** then computed the TIMF using the M_(2)tidal source as an example and validated our method by comparing it with results obtained from spherical harmonic finite element and integral equation ***,utilizing the computed high-precision M_(2),N_(2),and O1 TIMF signals,we marked global observatories capable of observing strong M_(2),N_(2),and O1 TIMF signals and predicted alternative stations suitable for tide signal ***,we calculated TIMF at heights of 450 and 200 km for the Macao Science Satellite 1 and its subsequent *** results indicate that the amplitude of the tidal-induced magnetic field at

关键词： Ocean motional induction Electromagnetic induction Ocean tides Geomagnetic satellite Macao Science Satellite 1

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Preparation of Chemically Recyclable Poly(ether-alt-ester) by the Ring Opening Polymerization of Cyclic Monomers Synthesized by Coupling Glycolide and Epoxides

引用

Chinese Journal of Polymer Science 2024年第2期42卷 168-175,I0006页

作者： Feng ren Zhuang-Zhuang Liang Ming-Xin Niu Chen-yang Hu Xuan Pang Key Laboratory of Polymer Ecomaterials Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun130022China School of Applied Chemistry and Engineering University of Science and Technology of ChinaHefei230026China

Polyester and polyether are two key oxygenated polymers, and completely alternative sequence of poly(ester-alt-ether) could efficiently combine the advantages(including flexibility, degradability, etc.) of both segments. Currently, despite their copolymers could be synthesized from one-pot mixture of cyclic esters and epoxides, perfectly alternative microstructure is very challenging to realize and typically restricted to certain monomer pairs. Moving forward, synthesizing poly(ester-alt-ether) from commercially available and largescale monomers would be a significant advance. For example, successfully commercialized poly(glycolic acid)(PGA), which is not easily soluble in polymers due to its high crystallinity and is brittle and difficult to control the degradation cycle, would encounter a new paradigm if engineered into poly(ester-altether). In this work, starting from the design of monomer with hybrid structures, we successfully synthesized a series of 1,4-dioxan-2-one containing different substituents based on glycolide(GA) and epoxides using commercially available Salen-Cr(III) and PPNCl catalytic *** new monomers underwent ring-opening polymerization(ROP) to form a series of poly(ester-alt-ether) with perfectly alternating glycolic acid and propylene glycol repeat units under catalytic system of thiourea/base. The poly(ester-alt-ether) have significantly lower glass-transition temperature than PGA. Additionally, the poly(ester-alt-ether) can be chemically recovered to monomer using Sn(Oct)2 or 1,8-diazabicyclo[5.4.0]undecane-7-ene(DBU) as a catalyst in solution, thus establishing a closed-loop life cycle. From monomers derived from GA and epoxides, this work furnishes a novel strategy for the synthesis of poly(ester-alt-ether) with chemical recyclability.

关键词： Polyester Polyether Alternative copolymer Ring-opening polymerization

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Recent progress of two-dimensional metal-base catalysts in urea oxidation reaction

引用

Rare Metals 2024年第8期43卷 3607-3633页

作者： Qi-Xiang Huang Fang Wang Yong Liu Bi-Ying Zhang Fang-Ya Guo Zhong-Qiu Jia hao Wang Tian-Xiang yang Hai-Tao Wu Feng-Zhang ren Ting-Feng Yi School of Materials Science and Engineering Henan University of Science and TechnologyLuoyang 471000China School of Environmental Engineering and Chemistry Luoyang Institute of Science and TechnologyLuoyang 471023China Henan Province International Joint Laboratory of Materials for Solar Energy Conversion and Lithium Sodium Based Battery Luoyang 471023China School of Chemistry and Life Sciences Suzhou University of Science and TechnologySuzhou 215009China School of Materials Science and Engineering Northeastern UniversityShenyang110819China

Urea oxidation reaction(UOR)is an auxiliary water electrolysis hydrogen production technology developed in recent years to replace oxygen evolution reaction and reduce energy consumption,which can produce hydrogen more efficiently by low theoretical potential,reduce the average cost of electrochemical hydrogen production,and is a frontier research hotspot for renewable hydrogen ***-dimensional(2D)nanomaterials as electrocatalysts have many favorable potential,such as it can effectively reduce the resistivity of materials and increase the specific surface area with *** paper reviews the application of 2D materials in UOR in alkaline *** a cross-sectional comparison of various material performance data including overpotential,Tafel slope,electrochemical active surface area(ECSA)and it stability test was conducted,which could illustrate the differences between materials composed of different *** addition,the main challenges hindering the progress of research on 2D materials in urea electrocatalysis processes and promising materials in this field in future are summarized and *** is believed that this review will contribute to designing and analyzing highperformance 2D urea electrocatalysts for water splitting.

关键词： Water splitting Urea oxidation reaction Two-dimensional Transition metal compounds Noble/non-noble metals

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Transforming waste particles into valuable adsorbents via amyloid-mediated molecular engineering

引用

Science China Chemistry 2024年

作者： Qingmin yang Jian Zhao Yujia Zhang Xingyu Zhou hao ren Bowen Hu Zhongli Lei Lixin Chen Peng yang School of Material and Chemical Engineering Bengbu University Anhui Provincial Engineering Laboratory of Silicon-Based Materials School of Chemistry and Chemical Engineering Northwestern Polytechnical University Key Laboratory of Applied Surface and Colloid Chemistry Ministry of Education School of Chemistry and Chemical EngineeringShaanxi Normal University Xi'an Key Laboratory of Polymeric Soft Matter School of Chemistry and Chemical Engineering Shaanxi Normal University International Joint Research Center on Functional Fiber and Soft Smart Textile School of Chemistry and Chemical EngineeringShaanxi Normal University

The high-value utilization of industrial solid waste using a facile and eco-friendly process is of great interest and significance in reducing environmental pollution and developing a green circular economy. Herein, we propose an amyloid-mediated molecular engineering strategy to transform particulate waste into valuable adsorbents for metal ions. Our method has the advantage of aqueous solution fabrication under mild conditions without the use of high-temperature hydrothermal methods and toxic chemical reagents. Amyloid-mediated molecular engineering manipulates the phase transition of bovine serum albumin（BSA）on particulate waste surfaces, resulting in a remarkable ～3.1 times improvement in the adsorption capacity of fly ash, a typical industrial solid waste for gold ions after modification with the phase-transitioned BSA（PTB）. The resultant adsorption ability was 69–1,980 times higher than those of conventional and emerging adsorbent materials such as ion exchange resins, activated carbon（AC）, covalent organic frameworks（COFs）, and metal-organic frameworks（MOFs）. We further demonstrated the application of our PTB-modified materials in the recovery of precious metals from low-grade gold ore and electronic waste leachates. Consequently, this strategy could increase the value of waste materials nearly 27 times. In addition, this method is generally extendable to other conventional industrial adsorbents such as resin, clay, and Al2O3, and enhances their adsorption capabilities at least twofold. Overall, this work provides a simple and green approach for improving the adsorption performance of solid particles, and is expected to develop into a universal strategy for transforming waste particles into high-value-added products.

关键词：

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Effect of solute Ce,Mn,and Si on mechanical properties of silicon steel:insights from DFT calculations

引用

Journal of Iron and Steel Research International 2024年第3期31卷 700-709页

作者： Xiang-jun Liu Ji-chun yang Hui-ping ren Xiao-bin Jia Ming-yi Zhang Chang-qiao yang School of Materials and Metallurgy Inner Mongolia University of Science and TechnologyBaotou 014010Inner MongoliaChina Key Laboratory of Integrated Exploitation of Bayan Obo Multi-Metal Resource Inner Mongolia University of Science and TechnologyBaotou 014010Inner MongoliaChina Inner Mongolia North Heavy Industries Group Co. Ltd.Baotou 014010Inner MongoliaChina Inner Mongolia Metal Material Research Institute Baotou 014010Inner MongoliaChina

The influence of solute Ce,Mn,and Si on the mechanical properties of silicon steel was investigated by first-principles ***,Mn,and Si can all be solubilized in Fe *** significantly reduces the incompressibility and rigidity of the system but also significantly improves the toughness and *** effect of Mn on mechanical properties of the system is not *** has a significant effect on the improvement in incompressibility and rigidity but a limited effect on the improvement in toughness and *** metallic bond strength of Fe-Ce,Fe-Mn,and Fe-Si doped systems is weaker than that of the pure Fe system,which can be used to explain the reduction in the incompressibility and rigidity of these doped *** relatively high electron cloud density in the doped system may be responsible for the increase in toughness.

关键词： Silicon steel Rare earth First-principles calculation Elastic modulus Electronic structure

来源：

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

N-acetylcysteine ameliorates erectile dysfunction in rats with hyperlipidemia by inhibiting oxidative stress and corpus cavernosum smooth muscle cells phenotypic modulation

引用

Asian Journal of Andrology 2024年第1期26卷 99-106页

作者： Wei Ding Jun-Hong Fan Li-ren Zhong Nan-Xiong Wang Lu-hao Liu Hai-Bo Zhang Li Wang Ming-Qiang Wang Bing-Lin He An-yang Wei Department of Urology The First Affiliated Hospital of Guizhou University of Traditional Chinese MedicineGuiyang 550002China Department of Urology Guangdong Provincial People's HospitalGuangdong Academy of Medical SciencesGuangzhou 510000China Department of Urology Nanfang HospitalSouthern Medical UniversityGuangzhou 510000China Department of Urology Shenzhen Immigration Inspection General Station HospitalShenzhen 518000China Department of Organ Transplantation The Second Affiliated Hospital of Guangzhou Medical UniversityGuangzhou 510000China Department of Endocrinology The First Affiliated Hospital of Guizhou University of Traditional Chinese MedicineGuiyang 550002China

Hyperlipidemia is a major risk factor for erectile dysfunction(ED).Oxidative stress and phenotypic modulation of corpus cavernosum smooth muscle cells(CcSMCs)are the key pathological factors of ED.N-acetylcysteine(NAC)can inhibit oxidative stress;however,whether NAc can alleviate pathological variations in the corpus cavernosum and promote erectile function recovery in hyperlipidemic rats remains unclear.A hyperlipidemia model was established using 27 eight-week-old male Sprague-Dawley(SD)rats fed a high-fat and high-cholesterol diet(hyperlipidemic rats,HR).In addition,9 male SD rats were fed a normal diet to serve as controls(NC).HR rats were divided into three groups:HR,HR+normal saline(NS),and HR+NAC(n=9 for each group;NS or NAc intraperitoneal injections were administered daily for 16 weeks).Subsequently,the lipid profiles,erectile function,oxidative stress,phenotypic modulation markers of ccsMCs,and tissue histology were *** experimental results revealed that erectile function was significantly impaired in the HR and HR+NS groups,but enhanced in the HR+NAC *** lipid levels,over-activated oxidative stress,and multi-organ lesions observed in the HR and HR+NS groups were improved in the HR+NAC ***,the HR group showed significant phenotypic modulation of CCSMCs,which was also inhibited by NAC *** report focuses on the therapeutic effect of NAc in restoring erectile function using a hyperlipidemic rat model by preventing CcSMC phenotypic modulationand attenuating oxidativestress.

关键词： erectile dysfunction hyperlipidemia N-acetylcysteine oxidative stress henotypic modulation

来源：

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

A toolbox for genetic manipulation in intestinal Clostridium symbiosum

引用

Synthetic and Systems Biotechnology 2024年第1期9卷 43-54页

作者： Pengjie yang Jinzhong Tian Lu Zhang Hui Zhang Gaohua yang Yimeng ren Jingyuan Fang yang Gu Weihong Jiang CAS-Key Laboratory of Synthetic Biology CAS Center for Excellence in Molecular Plant SciencesShanghai Institute of Plant Physiology and EcologyChinese Academy of SciencesShanghai200032China University of Chinese Academy of Sciences Beijing100049China Xianghu Laboratory Hangzhou311231China NHC Key Laboratory of Digestive Diseases Division of Gastroenterology and HepatologyShanghai Institute of Digestive DiseaseRenji HospitalSchool of MedicineShanghai Jiao Tong University145 Middle Shandong RoadShanghai200001China Shenzhen Branch Guangdong Laboratory for Lingnan Modern AgricultureGenome Analysis Laboratory of the Ministry of AgricultureAgricultural Genomics Institute at ShenzhenChinese Academy of Agricultural SciencesShenzhen518120China The Wallenberg Laboratory Department of Molecular and Clinical MedicineSahlgrenska AcademyUniversity of GothenburgBruna Straket 16Gothenburg41345Sweden

Gut microbes are closely related with human health,but remain much to *** symbiosum is a conditionally pathogenic human gut bacterium and regarded as a potential biomarker for early diagnosis of intestinal ***,the absence of an efficient toolbox that allows diverse genetic manipulations of this bacterium limits its in-depth ***,we obtained the complete genome sequence of *** ATCC 14940,a representative strain of *** this basis,we further developed a series of genetic manipulation methods for this ***,following the identification of a functional replicon pBP1 in *** ATCC 14940,a highly efficient conjugative DNA transfer method was established,enabling the rapid introduction of exogenous plasmids into ***,we constructed a dual-plasmid CRISPR/Cas12a system for genome editing in this bacterium,reaching over 60% repression for most of the chosen genes as well as efficient deletion(>90%)of three target ***,this toolbox was used for the identification of crucial functional genes,involving growth,synthesis of important metabolites,and virulence of *** ATCC *** work has effectively established and optimized genome editing methods in intestinal ***,thereby providing strong support for further basic and application research in this bacterium.

关键词： Gut Clostridium symbiosum Toolbox Gene overexpression Gene deletion Gene regulation

来源：

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

Can soil organic carbon sequestration and the carbon management index be improved by changing the film mulching methods in the semiarid region?

引用

Journal of Integrative Agriculture 2024年第5期23卷 1541-1556页

作者： Jialin yang Liangqi ren Nanhai Zhang Enke Liu Shikun Sun Xiaolong ren Zhikuan Jia Ting Wei Peng Zhang College of Agronomy Northwest A&F UniversityYangling 712100China Key Laboratory of Crop Physi-Ecology and Tillage Science in Northwestern Loess Plateau Ministry of Agriculture and Rural AfairsNorthwest A&FUniversityYangling 712100China Institute of Environment and Sustainable Development in Agriculture Chinese Academy of Agricultural SciencesBeijing 100081China College of Water Resources and Architectural Engineering Northwest A&F UniversityYangling 712100China

Plastic film mulching has been widely used to increase maize yield in the semiarid area of ***, whether long-term plastic film mulching is conducive to agricultural sustainability in this region remains controversial.A field experiment was initiated in 2013 with five different film mulching methods:(i) control method, flat planting without mulching (CK),(ii) flat planting with half film mulching (P),(iii) film mulching on ridges and planting in narrow furrows(S),(iv) full film mulching on double ridges (D), and (v) film mulching on ridges and planting in wide furrows (R).The effects on soil organic carbon (SOC) content, storage, and fractions, and on the carbon management index (CMI)were evaluated after nine consecutive years of plastic film *** results showed that long-term plastic film mulching generally maintained the initial SOC *** with no mulching, plastic film mulching increased the average crop yield, biomass yield, and root biomass by 48.38, 35.06, and 37.32%, respectively, which led to the improvement of SOC ***, plastic film mulching significantly improved CMI, and increased the SOC content by 13.59%, SOC storage by 7.47%and easily oxidizable organic carbon (EOC) by 13.78%on average,but it reduced the other labile *** sequestration and CMI were improved by refining the plastic film mulching *** S treatment had the best effect among the four mulching methods, so it can be used as a reasonable film mulching method for sustainable agricultural development in the semiarid area.

关键词： plastic film mulching soil organic carbon labile organic carbon fractions semiarid area

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：