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带大小结构的捕食-被捕食系统解的存在性(英文) 被引量:2
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作者 李燕 刘伟安 孔杨 《数学杂志》 CSCD 北大核心 2010年第6期973-979,共7页
本文研究了一类带有大小结构的捕食-被捕食系统. 利用特征线的方法,证明了此系统的初边值问题解的存在性. 最后,还给出了解是唯一的.
关键词 大小结构的捕食-被捕食系统 特征线方法 压缩映射
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排水防涝大小排水系统构建研究 被引量:4
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作者 周琪皓 杨新宇 +2 位作者 黄继军 张春洋 刘云帆 《水利规划与设计》 2020年第11期24-28,69,共6页
随着城市化进程的加快,暴雨洪涝灾害发生的频率越来越高,已成为制约城市经济发展的重要因素。以张家口和泉州古城为例,分别对比南北两座城市不同的气候地理特征,发现管网现状标准不足,尤其对大汇水片区暴雨强度公式存在适用误差,是造成... 随着城市化进程的加快,暴雨洪涝灾害发生的频率越来越高,已成为制约城市经济发展的重要因素。以张家口和泉州古城为例,分别对比南北两座城市不同的气候地理特征,发现管网现状标准不足,尤其对大汇水片区暴雨强度公式存在适用误差,是造成城市内涝的主要原因之一,但全面提升管网设计标准存在困难和局限。因此,以张家口和泉州古城为例,分别提出不同的大、小排水系统构建方式,经济有效地提升城市对降雨灾害的应对能力。 展开更多
关键词 排水防涝 大小排水系统 暴雨强度公式
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高天混合煤气采用大小火脉冲燃烧控制系统实际生产中的问题及处理 被引量:1
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作者 曾平贵 王朋 《中国西部科技》 2010年第6期29-29,13,共2页
衡阳华菱连轧管有限公司新建720周轧机组生产线中设有台车式热处理炉和外部机械化室式热处理炉,以高炉煤气和天然气的混合气为燃料,为国内首例,采用大小火脉冲燃烧控制系统。本文主要介绍了该系统在生产过程中出现的问题及解决办法,对... 衡阳华菱连轧管有限公司新建720周轧机组生产线中设有台车式热处理炉和外部机械化室式热处理炉,以高炉煤气和天然气的混合气为燃料,为国内首例,采用大小火脉冲燃烧控制系统。本文主要介绍了该系统在生产过程中出现的问题及解决办法,对类似工程项目具有借鉴意义。 展开更多
关键词 混合煤气 大小火脉冲控制系统 台车炉 室式炉
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G/M/1的反馈后优先排队但非抢占的排队系统中顾客的到达分布 被引量:4
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作者 边军辉 尹文运 张春燕 《西安文理学院学报(自然科学版)》 2009年第4期42-44,共3页
在得出G/M/1反馈后优先排队但非抢占的排队系统中到达顾客服务阶段数分布的概率母函数的基础上,采用取极限的方法求出了排队系统中顾客的到达分布,并进一步得出了G/M/1反馈后优先排队但非抢占的排队系统的平均系统大小.
关键词 概率母函数 顾客到达分布 平均系统大小
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探讨地铁施工中通风空调系统质量控制重点
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作者 王天蓉 《中国科技期刊数据库 工业A》 2023年第6期5-8,共4页
地铁作为一种极受人们欢迎交通工具,其通风与空调系统的设计与安装显得尤为重要。工程技术人员对通风系统结构要有清晰的认识,在施工时要有针对性地采取相应的施工措施,以保证施工质量。本文对地铁交通通风空调系统的基本构成进行了阐述... 地铁作为一种极受人们欢迎交通工具,其通风与空调系统的设计与安装显得尤为重要。工程技术人员对通风系统结构要有清晰的认识,在施工时要有针对性地采取相应的施工措施,以保证施工质量。本文对地铁交通通风空调系统的基本构成进行了阐述,对其在地铁通风空调系统施工中的注意事项进行了归纳,并提出了提高地铁通风空调系统安装质量的具体措施,以供相关工作人员参考。 展开更多
关键词 地铁通风空调系统 大小制冷系统 风管安装
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两种空调控制系统的原理分析与比较 被引量:2
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作者 宋祥龙 黄翔 +1 位作者 卫晨 王红原 《棉纺织技术》 CAS 北大核心 2013年第10期18-22,共5页
探讨两种空调控制系统的原理分析与比较。介绍了大小环境分区控制和温湿度独立控制两种空调系统的概念、产生背景和系统控制原理。并以潮湿地区为例,选取具体的设备,对两种空调系统的空气处理过程、空调区域热湿负荷的分配以及热湿平衡... 探讨两种空调控制系统的原理分析与比较。介绍了大小环境分区控制和温湿度独立控制两种空调系统的概念、产生背景和系统控制原理。并以潮湿地区为例,选取具体的设备,对两种空调系统的空气处理过程、空调区域热湿负荷的分配以及热湿平衡做了详细的对比。指出:大小环境分区控制系统是按空调的目的对纺织车间进行区域划分,并进行空调分区控制;温湿度独立控制系统是对室内空气按设计状态参数划分,并分别进行独立控制。 展开更多
关键词 大小环境分区控制系统 温湿度独立控制系统 负荷分配 热湿平衡 室内空气
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地铁车站环控通风与空调系统分析 被引量:6
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作者 沙国荣 邓嘉 +1 位作者 陈正泉 钱青 《南京工业职业技术学院学报》 2018年第4期13-15,共3页
以地铁车站环控通风与空调系统为研究对象,分析了地铁车站通风与空调系统在不同模式下的运行条件和运行方式,并对地铁隧道通风系统作了简要介绍,对地铁通风与空调系统的工程应用具有一定的指导意义。
关键词 地铁环控 通风与空调 大小系统 运行模式
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地铁通风空调系统安装注意事项及质量提升措施 被引量:3
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作者 唐宝银 《工程技术研究》 2022年第11期110-112,共3页
地下轨道交通是城市热门的交通方式,地铁内部的通风空调系统的设计及安装十分重要,技术人员需对通风系统的组成有清晰的了解,在具体安装时重点关注安装过程中的注意事项,并采取相应措施提高整体安装质量。文章介绍了地铁通风空调系统的... 地下轨道交通是城市热门的交通方式,地铁内部的通风空调系统的设计及安装十分重要,技术人员需对通风系统的组成有清晰的了解,在具体安装时重点关注安装过程中的注意事项,并采取相应措施提高整体安装质量。文章介绍了地铁通风空调系统的基本组成,总结了地铁通风空调系统安装的注意事项,并提出了提高地铁通风空调系统安装质量的具体措施,以供相关工作人员参考。 展开更多
关键词 地铁通风空调系统 大小制冷系统 风管安装
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食物链长度远因与近因研究进展综述 被引量:7
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作者 王玉玉 徐军 雷光春 《生态学报》 CAS CSCD 北大核心 2013年第19期5990-5996,共7页
食物链长度是生态系统的基本属性,其变化决定着群落结构和生态系统功能。稳定同位素分析技术的进步推进了生态系统中食物链长度决定因子相关研究的开展。尽管近期的研究证明了食物链长度与资源可利用性、生态系统大小、干扰等远因之间... 食物链长度是生态系统的基本属性,其变化决定着群落结构和生态系统功能。稳定同位素分析技术的进步推进了生态系统中食物链长度决定因子相关研究的开展。尽管近期的研究证明了食物链长度与资源可利用性、生态系统大小、干扰等远因之间的关系,但是对于食物网内部结构变化这一近因对食物链长度的影响作用关注较少。综述了边界明确和开放类型淡水生态系统中食物链长度的相关研究进展;探讨了远因和近因机制在决定食物链长度中的作用;给出了判断不同层次和尺度上决定食物链长度机制的概念框架;为今后更好的开展不同生态系统间食物链长度的比较研究提出了建议。 展开更多
关键词 食物链长度 资源可利用性 生态系统大小 干扰 食物网结构 远因和近因机制
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中国城市内涝防治与大小排水系统分析 被引量:165
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作者 车伍 杨正 +1 位作者 赵杨 李俊奇 《中国给水排水》 CAS CSCD 北大核心 2013年第16期13-19,共7页
近年来,由于我国城市内涝灾害频发,如何科学、有效地解决城市内涝成为政府与专业人员关注的热点。简要分析、总结了城市内涝的成因及洪涝关系、我国城市内涝防治思路的局限性以及部分发达国家针对洪涝的分类与治理情况。然后针对大小排... 近年来,由于我国城市内涝灾害频发,如何科学、有效地解决城市内涝成为政府与专业人员关注的热点。简要分析、总结了城市内涝的成因及洪涝关系、我国城市内涝防治思路的局限性以及部分发达国家针对洪涝的分类与治理情况。然后针对大小排水系统的概念、组成、应用情况及其局限性进行了系统梳理,并提出积极推进风险评估,为大小排水系统科学的规划设计提供科学依据。最后选择某城区和大型住宅区两个不同尺度的典型案例,简要介绍其大小排水系统构成与规划设计和内涝综合防治的要点和效果。 展开更多
关键词 城市内涝 大小排水系统 风险评估
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Influence of Cropping Systems on Soil Properties in Semi-arid Conditions of Setif, Algeria
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作者 Abdelhamid Mekhlouf Noureddine Rouag +3 位作者 Rabah Boukhadra Selma Chenni Mohamed Fenni Mahfoud Makhlouf 《Journal of Agricultural Science and Technology(A)》 2013年第8期653-658,共6页
The effects of two culture systems, conventional and no-till combined the previous crop (lentil and wheat) on soil properties were studied in the experimental site of the station Technical Institute for Field Crops ... The effects of two culture systems, conventional and no-till combined the previous crop (lentil and wheat) on soil properties were studied in the experimental site of the station Technical Institute for Field Crops (ITGC) Setif (Algeria) during the crop year 2011/2012. The results indicate that the no-till system affects positively the variables of soil properties and the organic matter has a rate of 2.89% compared to 2.44% in conventional tillage. If the conventional system has an infiltration of moisture relatively higher than that observed for no-till throughout the cycle, the no-tillage is distinguished by a higher storage of moisture at the end of cycle wheat cultivation. The results also indicate that the density (1.44 g/cm), permeability (22.79 cm/h) and soil compaction (12.51 kg/cm) in no-till were significantly higher compared to conventional tillage 1.35 g/cm, 14.13 cm/h, 7.40 kg/cm, respectively. 展开更多
关键词 Conventional tillage no-ill preceding crop bulk density INFILTRATION COMPACTION organic matter.
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Thermal properties of open-celled aluminum foams prepared by two infiltration casting methods 被引量:2
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作者 王辉 周向阳 +2 位作者 龙波 文康 杨焘 《Journal of Central South University》 SCIE EI CAS 2014年第7期2567-2571,共5页
Contrastive research was carried out to study the thermal properties of open-celled aluminum foams prepared by counter-gravity infiltration casting system and the traditional process respectively.The experimental resu... Contrastive research was carried out to study the thermal properties of open-celled aluminum foams prepared by counter-gravity infiltration casting system and the traditional process respectively.The experimental results show that the thermal conductivity coefficients of aluminum foams prepared by two different infiltration methods have similar increasing trend with the increase of particle size;along with the reducing porosity,the thermal conductivity coefficients will be enhanced oppositely.However,with the same particle size,the open-celled aluminum foam prepared by the former method has a higher thermal conductivity coefficient obviously.It is largely because that the sample prepared by counter-gravity infiltration casting has a lower void content and better dense crystallization of metal-matrix after the constant pressure process. 展开更多
关键词 open-celled aluminum foams counter-gravity infiltration casting thermal conductivity coefficient particle size POROSITY
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Transceiver Optimization for Multi-Antenna Device-to-Device Communications 被引量:1
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作者 Daohua Zhu Yajuan Guo +4 位作者 Lei Wei Chaoyang Zhu Biyao Huang Wei Xu Chunming Zhao 《China Communications》 SCIE CSCD 2016年第5期110-121,共12页
It has been shown that the deployment of device-to-device(D2D) communication in cellular systems can provide better support for local services. However, improper design of the hybrid system may cause severe interferen... It has been shown that the deployment of device-to-device(D2D) communication in cellular systems can provide better support for local services. However, improper design of the hybrid system may cause severe interference between cellular and D2D links. In this paper, we consider transceiver design for the system employing multiple antennas to mitigate the interference. The precoder and decoder matrices are optimized in terms of sum mean squared error(MSE) and capacity, respectively. For the MSE minimization problem, we present an alternative transceiver optimization algorithm. While for the non-convex capacity maximization problem, we decompose the primal problem into a sequence of standard convex quadratic programs for efficient optimization. The evaluation of our proposed algorithms for performance enhancement of the entire D2D integrated cellular system is carried out through simulations. 展开更多
关键词 device-to-device communication interference mitigation joint transceiver design multiple antennas
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Effect of floor level slit exhaust ventilation system on distribution of house dust 被引量:1
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作者 吕阳 H.Yoshino +3 位作者 R.Takaki R.Kurihara A.Mochida H.Yonekura 《Journal of Central South University》 SCIE EI CAS 2012年第3期696-702,共7页
Based on the fact that the house dust usually falls on the ground, the floor level slit exhaust ventilation system including inlet located at the ceiling and outlet of slit exhaust installed at comer between wall and ... Based on the fact that the house dust usually falls on the ground, the floor level slit exhaust ventilation system including inlet located at the ceiling and outlet of slit exhaust installed at comer between wall and floor was considered. Experiments and simulations were performed to investigate the flow and diffusion fields that are affected by this floor level slit exhaust ventilation system. The characteristics of airflow with experiments and computation fluid dynamics (CFD) are generally similar except airflow at the location of impinging flow and the location right below the inlet. Riboflavin particles were used as the house dust. For the spatial distribution of riboflavin particles in the ventilation system before operation, due to the influence of gravity, different sizes of particles show smooth decay curve. After floor level slit exhaust ventilation system is operated, the decay rate of the particles becomes faster than that after the ventilation system is powered on, and the particles with diameter of 0.5-3.0 μm in the experimental data and calculated values show good agreement. 展开更多
关键词 house dust floor level slit exhaust riboflavin particles computational fluid dynamics
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Discussion on Selection of Pulverizer and Moisture of Pulverized Coal for Lignite Boilers
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作者 Zhang Yun Li Weidong +1 位作者 Xu Chuankai Zhang Jingwu 《Electricity》 2012年第4期25-30,共6页
In China,the abrasion index and the free moisture are regarded as the criteria for determining whether the medium-speed pulverizer or the fan pulverizer could be selected.Based on comprehensive studies on foreign meth... In China,the abrasion index and the free moisture are regarded as the criteria for determining whether the medium-speed pulverizer or the fan pulverizer could be selected.Based on comprehensive studies on foreign methods for choosing the pulverizing system for lignite boilers,it is suggested that the particle size of coal,the drying time,the drying temperature and the humidity should be taken into account when measuring the free moisture of lignite,and the total moisture could also be the principle for type selection of pulverizer for lignite boilers.Furthermore,the determination of pulverized-coal moisture has great influence on the running of pulverizing systems.The actual moisture of certain pulverized coals is compared with that calculated with different methods and a feasible method for determining the moisture of the pulverized coal is suggested. 展开更多
关键词 lignite boiler type selection of pulverizer moisture of pulverized coal
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M/M/1反馈后优先排队但非抢占的排队系统中的顾客数分布的初步分析 被引量:7
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作者 边军辉 庞秀梅 尹文运 《吉林师范大学学报(自然科学版)》 2008年第2期84-86,共3页
本文在求得系统中等待服务的服务要求数的分布的基础之上,根据系统中等待服务的服务要求数和系统中顾客数的关系,求出系统中顾客数的分布,最后求出了M/M/1反馈后优先排队但非抢占的排队系统中的平均系统大小.
关键词 等待服务的服务要求数 系统中顾客数 平均系统大小
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场耦合忆阻神经网络的电活动 被引量:9
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作者 周倩 韦笃取 《计算物理》 CSCD 北大核心 2020年第6期750-756,共7页
神经元之间除了突触耦合,还存在磁通耦合.因此在传统的神经元模型中引入磁通量,并研究场耦合下神经网络的放电活动具有实际意义.建立一个含场耦合的Hodgkin-Huxley忆阻神经网络,引入神经元节点之间的距离权重,用磁通量描述时变电磁场,... 神经元之间除了突触耦合,还存在磁通耦合.因此在传统的神经元模型中引入磁通量,并研究场耦合下神经网络的放电活动具有实际意义.建立一个含场耦合的Hodgkin-Huxley忆阻神经网络,引入神经元节点之间的距离权重,用磁通量描述时变电磁场,采用磁控忆阻器实现膜电位和磁通量之间的耦合.探讨距离权重和系统大小对神经网络放电活动的影响.研究发现,随着权重增大,神经网络放电活动增强,且系统规模越大,诱导神经元兴奋性的权重阈值越大,系统大小不影响神经网络活性随距离权重变化的规律.在不同的权重值下,神经网络活性随系统大小变化的规律明显不同.研究表明,距离权重和系统大小对含场耦合的忆阻神经网络放电活动有重要影响,其中距离权重起主导作用. 展开更多
关键词 忆阻神经网络 场耦合 距离权重 系统大小
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Modulation of Soil Particle Size and Nutrient Availability in the Maize Rhizosheath 被引量:8
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作者 MA Wei LI Xue-Xian LI Chun-Jian 《Pedosphere》 SCIE CAS CSCD 2011年第4期483-490,共8页
Root exudates,microorganism colonization and soil aggregates together form the rhizosheath,a special cylinder of micro-ecosystem adhering to the root surface.To study how the rhizosheath affects soil structure and nut... Root exudates,microorganism colonization and soil aggregates together form the rhizosheath,a special cylinder of micro-ecosystem adhering to the root surface.To study how the rhizosheath affects soil structure and nutrient distribution,we analyzed the impact of maize rhizosheath on soil particle size and nutrient availability in pot and field experiments.The results showed that there was a significant size decrease of soil particles in the rhizosheath.Meanwhile,the soil mineral nitrogen in the rhizosheath was significantly higher than that in the rhizosphere or bulk soil at tasseling and maturity stages of maize.The contents of Fe and Mn were also differentially altered in the rhizosheath.Rhizosheath development,indicated by a dry weight ratio of rhizosheath soil to the root,was relatively independent of root development during the whole experimental period.The formation of maize rhizosheath contributed to the modulation of soil particle size and nutrient availability.The subtle local changes of soil physical and chemical properties may have profound influence on soil formation,rhizospheric ecosystem initiation,and mineral nutrient mobilization over the long history of plant evolution and domestication. 展开更多
关键词 MICRONUTRIENT mineral nitrogen mucilage RHIZOSPHERE root exudates
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Multi-objective optimization in quantum parameter estimation 被引量:2
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作者 BeiLi Gong Wei Cui 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS CSCD 2018年第4期30-35,共6页
We investigate quantum parameter estimation based on linear and Kerr-type nonlinear controls in an open quantum system, and consider the dissipation rate as an unknown parameter. We show that while the precision of pa... We investigate quantum parameter estimation based on linear and Kerr-type nonlinear controls in an open quantum system, and consider the dissipation rate as an unknown parameter. We show that while the precision of parameter estimation is improved,it usually introduces a significant deformation to the system state. Moreover, we propose a multi-objective model to optimize the two conflicting objectives:(1) maximizing the Fisher information, improving the parameter estimation precision, and(2)minimizing the deformation of the system state, which maintains its fidelity. Finally, simulations of a simplified ε-constrained model demonstrate the feasibility of the Hamiltonian control in improving the precision of the quantum parameter estimation. 展开更多
关键词 quantum parameter estimation Fisher information multi-objective optimization
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Consensus of Flocks under M-Nearest-Neighbor Rules 被引量:1
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作者 CHEN Chen CHEN Ge GUO Lei 《Journal of Systems Science & Complexity》 SCIE EI CSCD 2015年第1期1-15,共15页
This paper investigates a class of flocks with an M-nearest-neighbor rule,where each agent's neighbors are determined according to M nearest agents with M being a given integer,rather than all the agents within a ... This paper investigates a class of flocks with an M-nearest-neighbor rule,where each agent's neighbors are determined according to M nearest agents with M being a given integer,rather than all the agents within a fixed metric distance as in the well-known Vicsek's model.Such a neighbor rule has been validated by biologists through experiments and the authors will prove that,similar to the Vicsek's model,such a new neighbor rule can also achieve consensus under some conditions imposed only on the system's speed and the number M,n,without resorting to any priori connectivity assumptions on the trajectory of the system.In particular,the authors will prove that if the number M is proportional to the population size n,then for any speed v,the system will achieve consensus with large probability if the population size is large enough. 展开更多
关键词 CONSENSUS multi-agent systems M-nearest neighbor random geometric graph topological distance.
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