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Aboveground carbon sequestration of Cunninghamia lanceolata forests:Magnitude and drivers

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Forest Ecosystems 2024年第1期11卷 32-41页

作者： Chen Wang Shuguang Liu Yu Zhu Andrew R.Smith Ying Ning Deming Deng National engineering Laboratory for Applied technology of forestry&Ecology in South China Central South University of Forestry and TechnologyChangsha 410004China technology Innovation center for Ecological Conservation and Restoration in Dongting Lake Basin Ministry of Natural ResourcesChangsha 410007China College of Life Science and technology Central South University of Forestry and TechnologyChangsha 410004China School of Ecology and Environment Hainan UniversityHaikou 570228China School of Natural Sciences Bangor UniversityGwyneddLL572UWUK College of forestry Central South University of Forestry and TechnologyChangsha 410004China Hunan Prospecting Designing&research General Institute for Agriculture Forestry&IndustryChangsha 410007China

Understanding the spatial variation,temporal changes,and their underlying driving forces of carbon sequestration in various forests is of great importance for understanding the carbon cycle and carbon management *** carbon density and sequestration in various Cunninghamia lanceolata forests,extensively cultivated for timber production in subtropical China,vary with biodiversity,forest structure,environment,and cultural factors remain poorly explored,presenting a critical knowledge gap for realizing carbon sequestration supply potential through *** on a large-scale database of 449 permanent forest inventory plots,we quantified the spatial-temporal heterogeneity of aboveground carbon densities and carbon accumulation rates in Cunninghamia lanceolate forests in Hunan Province,China,and attributed the contributions of stand structure,environmental,and management factors to the heterogeneity using quantile age-sequence analysis,partial least squares path modeling(PLS-PM),and hot-spot *** results showed lower values of carbon density and sequestration on average,in comparison with other forests in the same climate zone(i.e.,subtropics),with pronounced spatial and temporal ***,quantile regression analysis using carbon accumulation rates along an age sequence showed large differences in carbon sequestration rates among underperformed and outperformed forests(0.50 and 1.80 Mg·ha^(-1)·yr^(-1)).PLS-PM demonstrated that maximum DBH and stand density were the main crucial drivers of aboveground carbon density from young to mature ***,species diversity and geotopographic factors were the significant factors causing the large discrepancy in aboveground carbon density change between low-and high-carbon-bearing *** analysis revealed the importance of culture attributes in shaping the geospatial patterns of carbon *** work highlighted that retaining largesized DBH trees and increasing shade-t

关键词： Carbon density Carbon accumulation rate Forest age Spatial variation Cultural influence

Rapid Phase Ambiguity Elimination Methods for DOA Estimator via Hybrid Massive MIMO Receive Array

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Chinese Journal of Electronics 2024年第1期33卷 175-184页

作者： Xichao ZHAN Zhongwen SUN Feng SHU Yiwen CHEN Xin CHENG Yuanyuan WU Qi ZHANG Yifan LI Peng ZHANG School of information and Communication engineering Hainan University School of Electronic and Optical engineering Nanjing University of Science and Technology

For a sub-connected hybrid multiple-input multiple-output(MIMO) receiver with K subarrays and N antennas, there exists a challenging problem of how to rapidly remove phase ambiguity in only single time-slot. A direction of arrival(DOA) estimator of maximizing received power(Max-RP) is proposed to find the maximum value of K-subarray output powers, where each subarray is in charge of one sector, and the center angle of the sector corresponding to the maximum output is the estimated true DOA. To make an enhancement on precision, Max-RP plus quadratic interpolation(Max-RP-QI) method is designed. In the proposed Max-RP-QI, a quadratic interpolation scheme is adopted to interpolate the three DOA values corresponding to the largest three receive powers of *** achieve the Cramer Rao lower bound, a Root-MUSIC plus Max-RP-QI scheme is developed. Simulation results show that the proposed three methods eliminate the phase ambiguity during one time-slot and also show low computational complexities. The proposed Root-MUSIC plus Max-RP-QI scheme can reach the Cramer Rao lower bound,and the proposed Max-RP and Max-RP-QI are still some performance losses 2–4 d B compared to the Cramer Rao lower bound.

关键词： Phased arrays Interpolation Wireless sensor networks Direction-of-arrival estimation Simulation Receiving antennas Massive MIMO

Orbit Weighting Scheme in the Context of Vector Space information Retrieval

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Computers, Materials & Continua 2024年第7期80卷 1347-1379页

作者： Ahmad Ababneh Yousef Sanjalawe Salam Fraihat Salam Al-E’mari Hamzah Alqudah Department of Computer Science Faculty of Information TechnologyAmerican University of MadabaAmman11821Jordan Department of Cybersecurity Faculty of Information TechnologyAmerican University of MadabaAmman11821Jordan Artificial Intelligence research center(AIRC) College of Engineering and Information TechnologyAjman UniversityP.O.Box 346Ajman13306United Arab Emirates information Security Department Faculty of Information TechnologyUniversity of PetraAmman11196Jordan Department of Data Science and Artificial Intelligence Faculty of Information TechnologyAmerican University of MadabaAmman11821Jordan

This study introduces the Orbit Weighting Scheme(OWS),a novel approach aimed at enhancing the precision and efficiency of Vector Space information retrieval(IR)models,which have traditionally relied on weighting schemes like tf-idf and *** conventional methods often struggle with accurately capturing document relevance,leading to inefficiencies in both retrieval performance and index size *** proposes a dynamic weighting mechanism that evaluates the significance of terms based on their orbital position within the vector space,emphasizing term relationships and distribution patterns overlooked by existing *** research focuses on evaluating OWS’s impact on model accuracy using information Retrieval metrics like Recall,Precision,InterpolatedAverage Precision(IAP),andMeanAverage Precision(MAP).Additionally,we assessOWS’s effectiveness in reducing the inverted index size,crucial for model *** compare OWS-based retrieval models against others using different schemes,including tf-idf variations and *** reveal OWS’s superiority,achieving a 54%Recall and 81%MAP,and a notable 38%reduction in the inverted index *** highlights OWS’s potential in optimizing retrieval processes and underscores the need for further research in this underrepresented area to fully leverage OWS’s capabilities in information retrieval methodologies.

关键词： information retrieval orbit weighting scheme semantic text analysis Tf-Idf weighting scheme vector space model

Gradient sparsification for efficient wireless federated learning with differential privacy

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Science China(information Sciences) 2024年第4期67卷 272-288页

作者： Kang WEI Jun LI Chuan MA Ming DING Feng SHU Haitao ZHAO Wen CHEN Hongbo ZHU School of Electronic and Optical engineering Nanjing University of Science and Technology Zhejiang Lab Key Laboratory of Computer Network and information Integration(Southeast University) Ministry of Education Data61 Commonwealth Scientific and Industrial Research Organisation School of information and Communication engineering Hainan University School of Communications and information engineering Nanjing University of Posts and Telecommunications School of Electronic information and Electrical engineering Shanghai Jiao Tong University

Federated learning(FL) enables distributed clients to collaboratively train a machine learning model without sharing raw data with each other. However, it suffers from the leakage of private information from uploading models. In addition, as the model size grows, the training latency increases due to the limited transmission bandwidth and model performance degradation while using differential privacy(DP)protection. In this paper, we propose a gradient sparsification empowered FL framework with DP over wireless channels, to improve training efficiency without sacrificing convergence performance. Specifically, we first design a random sparsification algorithm to retain a fraction of the gradient elements in each client’s local model, thereby mitigating the performance degradation induced by DP and reducing the number of transmission parameters over wireless channels. Then, we analyze the convergence bound of the proposed algorithm, by modeling a non-convex FL problem. Next, we formulate a time-sequential stochastic optimization problem for minimizing the developed convergence bound, under the constraints of transmit power, the average transmitting delay, as well as the client’s DP requirement. Utilizing the Lyapunov drift-plus-penalty framework, we develop an analytical solution to the optimization problem. Extensive experiments have been implemented on three real-life datasets to demonstrate the effectiveness of our proposed algorithm. We show that our proposed algorithms can fully exploit the interworking between communication and computation to outperform the baselines, i.e., random scheduling, round robin, and delay-minimization algorithms.

关键词： federated learning differential privacy gradient sparsification Lyapunov drift convergence analysis

Pre-combustion mercury removal with co-production of hydrogen via coal electrolysis

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Journal of Environmental Sciences 2024年第2期136卷 382-389页

作者： Xiang Lyu Runming Tao Tianyu Zhang Chemical and Biomolecular engineering Department Ohio University165 Stocker CenterAthensOH45701USA Electrification and Energy Infrastructures Division Oak Ridge National LaboratoryOak RidgeTN37831USA Beijing Key Lab for Source Control technology of Water Pollution College of Environmental Science and EngineeringBeijing Forestry UniversityBeijing 100083China engineering research center for Water Pollution Source Control&Eco-remediation College of Environmental Science and EngineeringBeijing Forestry UniversityBeijing 100083China

Pre-combustion mercury removal via coal electrolysis was performed and investigated on a bench-scale coal electrolytic cell(CEC)systemically,and factorial design was used to determine the effect of different operating conditions(coal particle size,operating temperature,operating cell voltage,and flow rate of slurry)on the percentage of mercury removal,percentage of ash removal,and dry heating value *** results showed that the operating cell voltage,as well as the interaction between operating cell voltage and coal particle size,are significant factors in the percentage of mercury *** is no significant factor in the percentage of ash removal and the dry heating value change,but the coal could be purified while keeping the dry heating value almost constant after electrolysis.A co-product of hydrogen could be produced during coal electrolysis with 50%lower energy consumption compared with water ***,a mechanism for mercury removal in coal was *** facts indicate that coal electrolysis is a promising method for precombustion mercury removal.

关键词： Pre-combustion mercury removal Coal electrolysis Ash removal Dry heating value Hydrogen production

Optical multipath self-interference cancellation for a wideband in-band full-duplex system using a silicon photonic modulator chip

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Chinese Optics Letters 2024年第7期22卷 126-131页

作者： Xiao Yu Jia Ye Lianshan Yan Tao Zhou Yue Zhu Peng Li Xihua Zou Wei Pan center for information Photonics and Communications School of Information Science and TechnologySouthwest Jiaotong UniversityChengdu 611756China Key Laboratory of Electronic information Control Southwest China Research Institute of Electronic EquipmentChengdu 610029China Microwave Photonics research Laboratory School of Electrical Engineering and Computer ScienceUniversity of OttawaOttawaONK1N6N5Canada

We propose and experimentally demonstrate a photonic method for wideband multipath self-interference cancellation using a silicon photonic modulator *** chip generates phase-inverted reference signals by leveraging the opposite phase between optical *** managing amplitude and phase imbalances between self-interference and reference signals,the approach rectifies discrepancies through consistent chip manufacturing and packaging *** photonic multi-dimensional multiplexing,including wavelength and polarization,enables the acquisition of multiple reference *** results show multipath cancellation depths of 25.53 dB and 23.81 dB for bandwidths of 500 MHz and 1 GHz,achieved by superimposing 2-path reference signals.

关键词： microwave photonics multipath self-interference silicon photonics

Wide Stopband Substrate Integrated Waveguide Filter Using Bisection and Trisection Coupling in Multilayer

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Chinese Journal of Electronics 2024年第2期33卷 436-442页

作者： Peng CHU Jianguo FENG Peng ZHU Lei GUO Long ZHANG Leilei LIU Guoqing LUO Ke WU College of Electronic and Optical engineering Nanjing University of Posts and Telecommunications National and Local Joint engineering Laboratory of RF Integration and Micro-Assembly technology School of information and Communication engineering Dalian University of Technology Guangdong Provincial Key Laboratory of Optoelectronic information Processing Chips and Systems Sun Yat-sen University College of Electronics and information engineering Shenzhen University School of Electronics and information Hangzhou Dianzi University Poly-Grames research center Polytechnique Montreal

This article presents a highly efficient method for substrate-integrated-waveguide（SIW） filters to achieve very wide stopbands. By employing the proposed trisection slots in addition to the bisection slots as the inter-coupling structures, all spurious modes below TE505 of a SIW filter working in the fundamental mode TE101（f0）can be eliminated without requiring additional structure or complex theoretical analysis, without affecting the design of the fundamental passbands, and without degrading the performance of the filters. For verification, two prototype filters are designed, fabricated, and measured with wide stopbands up to 4.15f0 and 4.83f0, respectively. The proposed technique could facilitate the development of high-performance wide-stopband SIW filters for microwave/wireless circuits and systems.

关键词： Microwave measurement Couplings Filters Prototypes Nonhomogeneous media Microwave theory and techniques Microwave circuits

Geometric error measuring,modeling,and compensation for CNC machine tools:A review

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Chinese Journal of Aeronautics 2024年第2期37卷 163-198页

作者： Zhao ZHANG Feng JIANG Ming LUO Baohai WU Dinghua ZHANG Kai TANG engineering research center of Advanced Manufacturing technology for Aero Engine(Northwestern Polytechnical University) Ministry of EducationXi’an 710072China Key Laboratory of High Performance Manufacturing for Aero Engine(Northwestern Polytechnical University) Ministry of Industry and Information TechnologyXi’an 710072China Department of Mechanical and Aerospace engineering Hong Kong University of Science and TechnologyHong KongChina

Geometric error,mainly due to imperfect geometry and dimensions of machine components,is one of the major error sources of machine *** that geometric error has significant effects on the machining quality of manufactured parts,it has been a popular topic for academic and industrial research for many years.A great deal of research work has been carried out since the 1970s for solving the problem and improving the machining *** have studied how to measure,detect,model,identify,reduce,and compensate the geometric *** paper presents a thorough review of the latest research activities and gives an overview of the state of the art in understanding changes in machine tool performance due to geometric *** advances in measuring the geometrical errors of machine tools are summarized,and different kinds of error identification methods of translational axes and rotation axes are illustrated ***,volumetric geometric error modeling,tracing,and compensation techniques for five-axis machine tools are emphatically ***,research challenges in order to improve the volumetric accuracy of machine tools are also highlighted.

关键词： Error compensation Error identification Error measurement Error modeling Geometric error Machine tools

The first mitogenome of Lauraceae(Cinnamomum chekiangense)

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Plant Diversity 2024年第1期46卷 144-148页

作者： Changwei Bi Ning Sun Fuchuan Han Kewang Xu Yong Yang David K.Ferguson State Key Laboratory of Tree Genetics and Breeding Co-Innovation Center for Sustainable Forestry in Southern ChinaKey Laboratory of Tree Genetics and Biotechnology of Educational Department of ChinaKey Laboratory of Tree Genetics and Silvicultural Sciences of Jiangsu ProvinceNanjing Forestry UniversityNanjing 210037China College of information Science and technology Nanjing Forestry UniversityNanjing 210037China research Institute of Subtropical forestry Chinese Academy of ForestryHangzhou 311400China Co-Innovation center for Sustainable forestry in Southern China College of Life SciencesNanjing Forestry UniversityNanjing 210037China Department of Paleontology University of ViennaViennaAustria

There are three distinct genetic systems in higher plants,the dominant nuclear genome and the semi-autonomous organelle genomes(plastids and mitochondria).In contrast to the conserved plastid genome(plastome),the plant mitochondrial genome(mitogenome)is characterized by an intriguing“evolutionary paradox”distinguished by a remarkably low mutation rate but with a significantly high rearrangement rate(Palmer and Herbon,1988;Lai et al.,2022).

关键词： autonomous distinguished Palmer