检索结果-南通市图书馆

Impacts of Aggregation Methods and Trophospecies Number on the Structure and Function of Marine Food Webs

在线全文

学校读者我要写书评

暂无评论

Journal of Ocean University of China 2024年第1期23卷 190-198页

作者： LI Pengcheng ZHANG Chongliang XU Binduo JI yupeng LI fan REN Yiping XUE Ying Laboratory of Fisheries Ecosystem Monitoring and Assessment College of FisheriesOcean University of ChinaQingdao 266003China Field Observation and Research Station of Haizhou Bay Fishery Ecosystem Ministry of EducationQingdao 266003China Shandong Marine Resources and Environment Research Institute Shandong Provincial Key Laboratory of Restoration for Marine EcologyYantai 264006China Laboratory for Marine Fisheries Science and Food Production Processes Laoshan LaboratoryQingdao 266237China

Aggregation of species with similar ecological properties is one of the effective methods to simplify food web researches.However,species aggregation will affect not only the complexity of modeling process but also the accuracy of models’outputs.Selection of aggregation methods and the number of trophospecies are the keys to study the simplification of food web.In this study,three aggregation methods,including taxonomic aggregation(TA),structural equivalence aggregation(SEA),and self-organizing maps(SOM),were analyzed and compared with the linear inverse model–Markov Chain Monte Carlo(LIM-MCMC)model.Impacts of aggregation methods and trophospecies number on food webs were evaluated based on the robustness and unitless of ecological net-work indices.Results showed that aggregation method of SEA performed better than the other two methods in estimating food web structure and function indices.The effects of aggregation methods were driven by the differences in species aggregation principles,which will alter food web structure and function through the redistribution of energy flow.According to the results of mean absolute percentage error(MAPE)which can be applied to evaluate the accuracy of the model,we found that MAPE in food web indices will increase with the reducing trophospecies number,and MAPE in food web function indices were smaller and more stable than those in food web structure indices.Therefore,trade-off between simplifying food webs and reflecting the status of ecosystem should be con-sidered in food web studies.These findings highlight the importance of aggregation methods and trophospecies number in the analy-sis of food web simplification.This study provided a framework to explore the extent to which food web models are affected by dif-ferent species aggregation,and will provide scientific basis for the construction of food webs.

关键词： LIM-MCMC model species aggregation trophospecies number aggregation methods food web indices

不同质量浓度的IAA、NAA处理对尤加利种子萌发的影响

在线全文

学校读者我要写书评

暂无评论

南方农业 2024年第5期18卷 13-17页

作者：张伟艳朱滨杰时健韩阳瑞朱秀秀范玉朋南通科技职业学院园艺与景观工程学院江苏南通226007 淮北师范大学生命科学学院安徽淮北235000

为了探究不同质量浓度吲哚乙酸和萘乙酸对尤加利种子萌发的影响,设置0.3、3、30、120 mg·L^(-1)4种生长素质量浓度,浸种时间分别为1.5、3、4.5、6 h,分别对尤加利银元和尤加利蓝宝贝浸种处理,进行尤加利种子的发芽率、发芽势和相对发... 详细信息

为了探究不同质量浓度吲哚乙酸和萘乙酸对尤加利种子萌发的影响,设置0.3、3、30、120 mg·L^(-1)4种生长素质量浓度,浸种时间分别为1.5、3、4.5、6 h,分别对尤加利银元和尤加利蓝宝贝浸种处理,进行尤加利种子的发芽率、发芽势和相对发芽率的研究。试验结果表明,0.3~120 mg·L^(-1)质量浓度的IAA激素浸种处理两种尤加利种子,浸种时间为1.5~6 h,其发芽率和发芽势均优于对照组,对两种尤加利种子的萌发均表现为促进作用。NAA处理条件下,两种尤加利种子的发芽率和发芽势受激素质量浓度和浸种时间影响较大,表现为低质量浓度促进、高质量浓度抑制,浸种时间短促进、浸种时间长抑制的关系。

关键词：生长素尤加利 IAA NAA 种子萌发

维普期刊数据库博看期刊

在线全文

学校读者我要写书评

暂无评论

生态城市与人地关系

生态学报 2022年第11期42卷 4313-4323页

作者：范育鹏方创琳中国科学院地理科学与资源研究所北京100101 中国科学院区域可持续发展分析与模拟重点实验室北京100101

生态城市作为当下探索人与自然协调共处、社会和谐进步、经济持续发展的实践,是实现可持续发展的重要举措。人地关系作为地理学研究的核心,是社会发展必须直面和探讨的重要问题。分别论述生态城市和人地关系相关研究的理念与框架、过程... 详细信息

生态城市作为当下探索人与自然协调共处、社会和谐进步、经济持续发展的实践,是实现可持续发展的重要举措。人地关系作为地理学研究的核心,是社会发展必须直面和探讨的重要问题。分别论述生态城市和人地关系相关研究的理念与框架、过程与机制、理论与方法的演变以及两者的区别。生态城市规划具备高度的综合性,在优化资源配置、调整空间布局、协调各项事业、改善城市功能等方面发挥重要作用,由单方面注重增长速度和规模转向重视城市增长容量、生态承载力、生活质量方面。人地关系研究旨在探索人地系统各要素间相互作用与系统行为及调控机制,其主旨问题随人地系统演变发生变异,准确分析人地关系面临着一系列理论、技术和数据方面的挑战。生态城市可以借助人地关系作为一个更加宏阔的系统框架,同时可为人地关系研究提供具体的工具和手段。复杂系统科学和综合集成方法是生态城市和人地关系的重点研究方向。生态城市与人地关系研究相互融合,能够更好地解决复杂问题,从而朝着共同目的—可持续发展迈进。

关键词：生态城市人地关系演变复杂系统耦合整合

在线全文

学校读者我要写书评

暂无评论

城市可持续发展新型定量研究方法进展

生态学报 2023年第8期43卷 3020-3031页

作者：范育鹏方创琳中国科学院地理科学与资源研究所北京100101 中国科学院区域可持续发展分析与模拟重点实验室北京100101

城市体现了集约化的发展方式,以仅占陆地3%的面积承载了世界一多半的人口,因此城市是人类社会可持续发展的主阵地,城市可持续发展是区域可持续发展的重要实践。研究试图从可持续发展的基本内涵着手,聚焦于城市尺度的研究,梳理了相关理... 详细信息

城市体现了集约化的发展方式,以仅占陆地3%的面积承载了世界一多半的人口,因此城市是人类社会可持续发展的主阵地,城市可持续发展是区域可持续发展的重要实践。研究试图从可持续发展的基本内涵着手,聚焦于城市尺度的研究,梳理了相关理论和概念演变历程,着重对新型定量方法——评价指标体系法、复杂系统建模、资源环境可持续性探索等进行综述。研究发现指标体系法常用于传统的城市可持续发展评估,大多是针对表象的分析,隔离了系统内部的组织关联,对系统机理探索不够。资源环境对人类社会的发展起到基础支撑作用,从资源环境可持续性出发研究可持续发展诞生了一些较为创新的方法,但研究集中在描述人类对自然的压力和影响,而对于自然对人类的反馈以及人对自然的积极改造探索不足,也很难直接表达系统整体的可持续性。弹性思维和复杂系统科学近年来被多次用于解释城市运行的灰箱模型,但研究稍浅。研究提出可将弹性思维和复杂系统科学结合起来,借助数据科学和计算科学的新兴方法,分析城市的可持续发展,深入探索可持续性的科学表达和深层机理,为解决复杂的城市问题提供科学指导,为城市可持续发展提供理论依据。

关键词：机理机制多尺度复杂性城市系统科学整合

A progressive framework for rotary motion deblurring

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2024年第2期32卷 159-172页

作者： Jinhui Qin Yong Ma Jun Huang fan fan You Du School of Electronic Information Wuhan UniversityWuhan430072China

The rotary motion deblurring is an inevitable procedure when the imaging seeker is mounted in the rotating missiles.Traditional rotary motion deblurring methods suffer from ringing artifacts and noise,especially for large blur extents.To solve the above problems,we propose a progressive rotary motion deblurring framework consisting of a coarse deblurring stage and a refinement stage.In the first stage,we design an adaptive blur extents factor(BE factor)to balance noise suppression and details reconstruction.And a novel deconvolution model is proposed based on BE factor.In the second stage,a triplescale deformable module CNN(TDM-CNN)is designed to reduce the ringing artifacts,which can exploit the 2D information of an image and adaptively adjust spatial sampling locations.To establish a standard evaluation benchmark,a real-world rotary motion blur dataset is proposed and released,which includes rotary blurred images and corresponding ground truth images with different blur angles.Experimental results demonstrate that the proposed method outperforms the state-of-the-art models on synthetic and real-world rotary motion blur datasets.The code and dataset are available at https://***/JinhuiQin/RotaryDeblurring.

关键词： Rotary motion deblurring Progressive framework Blur extents factor TDM-CNN

Impact of non-ideal UE hardware on cell-free massive MIMO network with centralized operation

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2024年第4期67卷 255-271页

作者： Ning LI Pingzhi fan Institute of Mobile Communications Southwest Jiaotong University

This paper investigates the impact of non-ideal user equipment(UE) hardware on a cell-free(CF) massive MIMO(mMIMO) network with centralized operation under spatially correlated channels. The minimum mean-squared error(MMSE) estimator can be derived with the help of the generic non-ideal UE hardware model. It is demonstrated that even if the effective signal-to-noise ratio approaches infinity, pilot contamination and imperfect hardware can cause a non-zero estimation error floor. After that, a lower bound is determined for the ergodic uplink capacity of the centralized CF mMIMO network under non-ideal UE hardware. Moreover, the optimal receive combining vector is obtained to maximize the uplink spectral efficiency(SE). The maximum ratio(MR) and regularized zero-forcing(RZF) combining schemes are offered as alternatives in light of the computational complexity of the MMSE receiver. Comparing the RZF to the MMSE scheme under different levels of hardware impairments, our findings indicate that the RZF receiver suffers a negligible loss in total SE. For MR combining, a novel closed-form uplink achievable SE expression is obtained based on the MMSE estimator and the use-and-then-forget bounding technique. This expression gives vital insights into the achievable uplink performance with UE hardware impairments. Besides, for various hardware impairment factors, the impact of pilot sequence length on average sum SE is disclosed for different receive combining schemes. To increase the overall SE of the max-min fairness scheme, a heuristic fractional power control scheme with UE hardware impairments is developed, which can essentially avoid sacrificing the SE of other UEs while maximizing the SE of the unluckiest UE in the whole network. Finally,our theoretical performance analysis and power control algorithm are validated by simulation results, and fundamental design guidelines are provided for selecting hardware satisfying the practical UE requirements.

关键词： cell-free massive MIMO centralized operation spatially correlated channels hardware impairments channel estimation uplink spectral efficiency optimal receive combining pilot length design fractional power control

Bi_(2)WO_(6)/AgInS_(2)S-scheme heterojunction:Efficient photodegradation of organic pollutant and toxicity evaluation

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2024年第3期170卷 200-211页

作者： Yanyan Zhao Xu fan Hongxing Zheng Enzhou Liu Jun fan Xuejun Wang College of Biology Pharmacy and Food Engineering Shangluo UniversityShangluo 726000China QinLing-Bashan Mountains Bioresources Comprehensive Development C.I.C. Shaanxi University of TechnologyHanzhong 723001China School of Chemical Engineering Northwest UniversityXi’an 710069China

Constructing of heterojunction was identified as a feasible way to improve photocatalytic activity of pho-tocatalyst.In this work,a n-p type Bi_(2)WO_(6)/AgInS_(2)S-scheme heterojunction was successfully prepared for organic pollutants degradation.This Bi_(2)WO_(6)/AgInS_(2)S-scheme heterojunction exhibited much higher pho-tocatalytic activity towards Rhodamine B(92.24%,expose to visible light for 60 min),norfloxacin(81.73%,expose to visible light for 90 min)and levofloxacin(87.46%,expose to visible light for 90 min)than pure Bi_(2)WO_(6)and pure AgInS_(2).Toxicity analysis indicated the low environmental toxicity of Rhodamine B degradation intermediates for Rye seeds and Sudangrass seeds germination and growth.Mechanism study displayed that AgInS_(2)and Bi_(2)WO_(6)work as the primary photocatalyst to form·O_(2)−and ·OH,respectively.The improved photocatalytic activity of the Bi_(2)WO_(6)/AgInS_(2)S-scheme heterojunction was due to the im-proved light response range and intensified carrier separation capability.Additionally,a S-scheme charge transfer mechanism including multiple charge transfer channels was proposed.This work could provide an effective strategy for organic pollutants degradation in wastewater.

关键词： Photocatalysis S-scheme heterojunction AgInS_(2) Bi_(2)WO_(6) Toxicity experiments

Soliton resolution and asymptotic stability of N-solutions for the defocusing Kundu–Eckhaus equation with nonzero boundary conditions

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

Communications in Theoretical Physics 2024年第1期76卷 1-6页

作者： Engui fan Yanxi Zhang School of Mathematical Sciences and Key Laboratory of Mathematics for Nonlinear Science Fudan UniversityShanghai200433China Tianjin Xinhua High School No.99 machang RoadTianjin300204China

In this paper,we address interesting soliton resolution,asymptotic stability of N-soliton solutions and the Painleve asymptotics for the Kundu-Eckhaus(KE)equation with nonzero boundary conditions iq_(t)+q_(xx)-2(l|q|^(2)-1)q+4β^(2)(lql^(4)-1)q+4iβ(lql^(2))_(x)q=0,q(x,0)=q_(0)(x)-±1,x→±∞.The key to proving these results is to establish the formulation of a Riemann-Hilbert(RH)problem associated with the above Cauchy problem and find its connection with the RH problem of the defocusing NLS equation.With the■-steepest descent method and the results of the defocusing NLS equation,we find complete leading order approximation formulas for the defocusing KE equation on the whole(x,t)half-plane including soliton resolution and asymptotic stability of N-soliton solutions in a solitonic region,Zakharov-Shabat asymptotics in a solitonless region and the Painlevéasymptotics in two transition regions.

关键词： defocusing Kundu-Eckhaus equation Riemann-Hilbert problems steepest descent method soliton resolution asymptotic stability Painleve transcendents

Flow instability of supercritical hydrocarbon fuel in a multi-channel cooling system

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2024年第2期37卷 283-295页

作者： Yichao JIN Kun WU Xuejun fan Institute of Applied Physics and Computational Mathematics Beijing 100094China Institute of Mechanics Chinese Academy of SciencesBeijing 100190China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China

Thermally-induced flow instabilities are a critical issue in multi-channel regenerative cooling systems.In particular,the interactions between Density-Wave Oscillations(DWO)and Flow Maldistribution(FMD)can result in complex and disastrous instability phenomena.This study investigates the instability behaviors of hydrocarbon fluid in a four-channel system with a constant heat flux ratio using both frequency-and time-domain methods.As the heat flux increases,the in-tube flow sequentially destabilizes in each channel and converges to new equilibrium states,leading to the emergence of FMD phenomena.This also causes the system eigenvalue to change repeatedly from negative to positive rather than increasing monotonically.Additionally,the system eigenvalues are between those of the two most unstable channels,indicating that the stability behavior of the entire system is dictated by the most unstable channel.After FMD occurs,flow oscillations are activated in channels with weak stability,and the in-tube flow is observed to evolve into various flow patterns,including stable flow,self-sustained oscillation,oscillation divergence,quasiperiodic oscillation,and oscillation excursion.The novel instability mode of oscillation excursion involves a spontaneous transition of operating states.It oscillates from an equilibrium state and then stabilizes at a new operational state after oscillation-induced redistribution.However,the newfound stable state may also be only temporary,with the in-tube flow regressing to the initial state,resulting in quasi-periodic oscillation.

关键词： Cooling Supercritical fluids Hydrocarbons Flow instability Flow maldistribution Density-wave oscillations