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ECOLOGICAL EFFECTS OF NITROGEN DEPOSITION ON URBAN FORESTS: AN OVERVIEW

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Frontiers of Agricultural Science and Engineering 2022年第3期9卷 445-456页

作者： Enzai DU Nan XIA Yuying GUO yuehan tian Binghe LI Xuejun LIU Wim DE VRIES State Key Laboratory of Earth Surface Processes and Resource Ecology Faculty of Geographical ScienceBeijing Normal UniversityBeijing 100875China School of Natural Resources Faculty of Geographical ScienceBeijing Normal UniversityBeijing 100875China National Academy of Agriculture Green Development Key Laboratory of Plant-Soil Interactions of Ministry of EducationCollege of Resources and Environmental SciencesChina Agricultural UniversityBeijing 100193China Wageningen University and Research Environmental ResearchPO Box 47NL-6700 AA Wageningenthe Netherlands Wageningen University and Research Environmental Systems Analysis GroupPO Box 47NL-6700 AA Wageningenthe Netherlands

The global urban area is expanding continuously,resulting in unprecedented emissions and deposition of reactive nitrogen(N)in urban ***,large knowledge gaps remain in the ecological effects of N deposition on urban forests that provide key ecosystem services for an increasing majority of city *** current understanding of the spatial patterns and ecological effects of N deposition in urban forests was synthesized based on a literature review of observational and experimental *** deposition generally increases closer to cities,resulting in an urban hotspot *** components of N deposition also shift across urban-suburban-rural gradients,showing higher ratios of ammonium to nitrate in and around urban *** ecological effects of N deposition on urban forest ecosystems are overviewed with a special focus on ecosystem N cycling,soil acidification,nutrient imbalances,soil greenhouse gas emissions,tree growth and forest productivity,and plant and soil microbial *** distinct effects of unprecedented N deposition on urban forests are discussed in comparison with the common effects in natural *** the existing research efforts,several key research needs are highlighted to fill the knowledge gaps in the ecological effects of N deposition on urban forests.

关键词： biodiversity carbon sequestration nitrogen deposition nutrient imbalance soil acidification urban forest

A Blockchain-Based Access Control Scheme for Reputation Value Attributes of the Internet of Things

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Computers, Materials & Continua 2024年第1期78卷 1297-1310页

作者： Hongliang tian Junyuan tian College of Electrical Engineering Northeast Electric Power UniversityJilin132012China

The Internet of Things(IoT)access controlmechanism may encounter security issues such as single point of failure and data *** address these issues,a blockchain-based IoT reputation value attribute access control scheme is ***,writing the reputation value as an attribute into the access control policy,and then deploying the access control policy in the smart contract of the blockchain system can enable the system to provide more fine-grained access control;Secondly,storing a large amount of resources fromthe Internet of Things in Inter Planetary File System(IPFS)to improve system throughput;Finally,map resource access operations to qualification tokens to improve the performance of the access control *** simulation experiments based on the Hyperledger Fabric *** simulation experimental results,it can be seen that the access control system can achieve more fine-grained and dynamic access control while maintaining high throughput and low time delay,providing sufficient reliability and security for access control of IoT devices.

关键词： Blockchain IoT access control Hyperledger Fabric

Robust adaptive radar beamforming based on iterative training sample selection using kurtosis of generalized inner product statistics

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Journal of Systems Engineering and Electronics 2024年第1期35卷 24-30页

作者： tian Jing ZHANG Wei School of Information and Electronics Beijing Institute of TechnologyBeijing 100081China National Key Laboratory of Electromagnetic Space Security Chengdu 610036China

In engineering application,there is only one adaptive weights estimated by most of traditional early warning radars for adaptive interference suppression in a pulse reputation interval(PRI).Therefore,if the training samples used to calculate the weight vector does not contain the jamming,then the jamming cannot be removed by adaptive spatial *** the weight vector is constantly updated in the range dimension,the training data may contain target echo signals,resulting in signal cancellation *** cope with the situation that the training samples are contaminated by target signal,an iterative training sample selection method based on non-homogeneous detector(NHD)is proposed in this paper for updating the weight vector in entire range *** principle is presented,and the validity is proven by simulation results.

关键词： adaptive radar beamforming training sample selection non-homogeneous detector electronic jamming jamming suppression

Transformer and GAN-Based Super-Resolution Reconstruction Network for Medical Images

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Tsinghua Science and Technology 2024年第1期29卷 197-206页

作者： Weizhi Du Shihao tian Arts&Sciences College Washington University in St.LouisSt.LouisMO 63130USA Department of Electric and Computing Engineering Cornell UniversityIthacaNY 14850USA

Super-resolution reconstruction in medical imaging has become more demanding due to the necessity of obtaining high-quality images with minimal radiation dose,such as in low-field magnetic resonance imaging(MRI).However,image super-resolution reconstruction remains a difficult task because of the complexity and high textual requirements for diagnosis *** this paper,we offer a deep learning based strategy for reconstructing medical images from low resolutions utilizing Transformer and generative adversarial networks(T-GANs).The integrated system can extract more precise texture information and focus more on important locations through global image matching after successfully inserting Transformer into the generative adversarial network for picture ***,we weighted the combination of content loss,adversarial loss,and adversarial feature loss as the final multi-task loss function during the training of our proposed model *** comparison to established measures like peak signal-to-noise ratio(PSNR)and structural similarity index measure(SSIM),our suggested T-GAN achieves optimal performance and recovers more texture features in super-resolution reconstruction of MRI scanned images of the knees and belly.

关键词： super-resolution image reconstruction Transformer generative adversarial network(GAN)

CCL9/CCR1 axis-driven chemotactic nanovesicles for attenuating metastasis of SMAD4-deficient colorectal cancer by trapping TGF-β

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Acta Pharmaceutica Sinica B 2024年第8期14卷 3711-3729页

作者： Boning Niu tianyi tian Lu Wang Yinmei tian tian tian Yuanyuan Guo Hu Zhou Zhiping Zhang Tongji School of Pharmacy Huazhong University of Science and TechnologyWuhan 430030China Department of Oncology Tongji HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhan 430030China Department of Pharmacy Liyuan HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhan 430030China School of Pharmaceutical Sciences Fujian Provincial Key Laboratory of Innovative Drug Target ResearchHigh Throughput Drug Screening PlatformXiamen UniversityXiamen 361102China National Engineering Research Center for Nanomedicine Huazhong University of Science and TechnologyWuhan 430030China Hubei Engineering Research Centre for Novel Drug Delivery System Huazhong University of Science and TechnologyWuhan 430030China

SMAD4 deficiency in colorectal cancer(CRC)is highly correlated with liver metastasis and high mortality,yet there are few effective precision therapies ***,we show that CCR1^(+)-granulocytic myeloid-derived suppressor cells(G-MDSCs)are highly infiltrated in SMAD4-deficient CRC via CCL15/CCR1 and CCL9/CCR1 axis in clinical specimens and mouse models,*** excessive TGF-β,secreted by tumor-infiltrated CCR1^(+)-G-MDSCs,suppresses the immune response of cytotoxic T lymphocytes(CTLs),thus facilitating ***,we develop engineered nanovesicles displaying CCR1 and TGFBR2 molecules(C/T-NVs)to chemotactically target the tumor driven by CCL9/CCR1 axis and trap TGF-βthrough TGF-β-TGFBR2 specific *** C/T-NVs counteract CCR1^(+)-G-MDSC infiltration through competitive responding CCL9/CCR1 axis.C/T-NVs-induced intratumoral TGF-βexhaustion alleviates the TGF-β-suppressed immune response of ***,C/T-NVs attenuate liver metastasis of SMAD4-deficient *** further exploration,high expression of programmed cell death ligand-1(PD-L1)is observed in clinical specimens of SMAD4-deficient *** C/T-NVs with anti-PD-L1 antibody(aPD-L1)induces tertiary lymphoid structure formation with sustained activation of CTLs,CXCL13^(+)-CD4^(+)T,CXCR5^(+)-CD20^(+)B cells,and enhanced secretion of cytotoxic cytokine interleukin-21 and IFN-γaround tumors,thus eradicating metastatic *** strategy elicits pleiotropic antimetastatic immunity,paving the way for nanovesicle-mediated precision immunotherapy in SMAD4-deficient CRC.

关键词： SMAD4-deficient CRC Metastasis G-MDSCs TGF-β CCR1 TGFBR2

Capturing metal clusters at the strong-interaction region to reverse Ostwald ripening

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Science China Materials 2024年第4期67卷 1363-1364页

作者： Shuheng tian Ding Ma Beijing National Laboratory for Molecular Sciences New Cornerstone Science LaboratoryCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China

High-temperature interactions induce sintering of metal nanoparticles(NPs) on heterogeneous catalyst surfaces, leading to reduced surface area and active site loss through Ostwald ripening [1]. This irreversible deactivation necessitates costly catalyst replacement, notably impacting metals like copper in hydrogenation and reforming reactions [2].

关键词： catalyst reforming irreversible

DeepSI:A Sensitive-Driven Testing Samples Generation Method of Whitebox CNN Model for Edge Computing

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Tsinghua Science and Technology 2024年第3期29卷 784-794页

作者： Zhichao Lian Fengjun tian School of Cyber Science and Engineering Nanjing University of Science and TechnologyNanjing 210094China

In recent years,Deep Learning(DL)technique has been widely used in Internet of Things(IoT)and Industrial Internet of Things(IIoT)for edge computing,and achieved good *** more and more studies have shown the vulnerability of neural ***,it is important to test the robustness and vulnerability of neural *** specifically,inspired by layer-wise relevance propagation and neural network verification,we propose a novel measurement of sensitive neurons and important neurons,and propose a novel neuron coverage criterion for robustness *** on the novel criterion,we design a novel testing sample generation method,named DeepSI,which involves definitions of sensitive neurons and important ***,we construct sensitive-decision paths of the neural network through selecting sensitive neurons and important ***,we verify our idea by setting up several experiments,then results show our proposed method achieves superior performances.

关键词： neuron sensitivity Layer-wise Relevance Propagation(LRP) neural network verification deeplearning testing

Frequency Domain Fatigue Evaluation on SCR Girth-Weld Based on Structural Stress

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China Ocean Engineering 2024年第2期38卷 255-270页

作者： ZHANG Long ZHAO tian-feng College of Safety and Ocean Engineering China University of Petroleum(Beijing)Beijing 102249China

The Steel Catenary Riser(SCR)is a vital component for transporting oil and gas from the seabed to the floating *** harsh environmental conditions and complex platform motion make the SCR’s girth-weld prone to fatigue *** structural stress fatigue theory and Master S-N curve method provide accurate predictions for the fatigue damage on the welded joints,which demonstrate significant potential and compatibility in multi-axial and random fatigue ***,we propose a new frequency fatigue model subjected to welded joints of SCR under multiaxial stress,which fully integrates the mesh-insensitive structural stress and frequency domain random process and transforms the conventional welding fatigue technique of SCR into a spectrum analysis technique utilizing structural ***,a full-scale FE model of SCR with welds is established to obtain the modal structural stress of the girth weld and the frequency response function(FRF)of modal coordinate,and a biaxial fatigue evaluation about the girth weld of the SCR can be achieved by taking the effects of multi-load correlation and pipe-soil interaction into *** research results indicate that the frequency-domain fatigue results are aligned with the time-domain results,meeting the fatigue evaluation requirements of the SCR.

关键词： SCR girth weld random vibration self(cross)power spectrum structural stress method biaxial fatigue damage

Frost heaving and crack initiation characteristics of tunnel rock mass in cold regions under low-temperature degradation

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Journal of Mountain Science 2024年第8期21卷 2844-2854页

作者： CHEN Wenhua XIANG tian School of Civil Engineering Beijing Jiaotong UniversityBeijing 202303China

Water freezing in rock fractures causes volumetric expansion and fracture development through frost *** study introduces a novel analytical model to investigate how uneven freezing force and surrounding rock pressure influence fracture initiation,based on mass conservation,elasticity,and water-ice phase transition principles.A model for rock fracture initiation considering freezing temperature,uneven freezing expansion,in-situ stress,and lateral pressure was proposed based on fracture *** for stress intensity factors were developed and validated using the phase field *** effects of rock elastic modulus anisotropy and critical fracture energy density on fracture initiation were also *** results show that the values of KI and KII exhibit an upward trend as the freezing temperature,uneven expansion,in-situ stress,and lateral pressure *** uneven freezing expansion has the most significant influence on KI and KII values among these *** the uneven freezing expansion coefficient increases to 0.5,the fracture initiation mode shifts from tensile fracture to shear *** the lateral pressure coefficient increases to 1,the fracture initiation mode shifts from tensile fracture to shear *** elastic modulus anisotropy causes fractures to propagate in a clockwise direction,forming a'butterfly'*** fracture energy density an isotropy causes counterclockwise deviation in propagation direction,resulting in branching paths and an'H'-shaped pattern.

关键词： Rock fractures Fracture water Uneven freezing expansion Phase field method Initiation angle Anisotropy