检索结果-南通市图书馆

在线全文

学校读者我要写书评

暂无评论

5G载波聚合在无线通信性能提升中的研究

移动信息 2024年第7期46卷 16-18,25页

作者：苏清章福建福诺移动通信技术有限公司福州350000

5G载波聚合(Carrier Aggregation,CA)作为5G通信技术的关键,具有重要的研究意义。它通过同时利用多个频段来提高数据传输速率、增加网络容量、优化用户体验,在移动通信领域具有巨大的应用潜力。文中探讨了5G载波聚合的基本原理,分析了... 详细信息

5G载波聚合(Carrier Aggregation,CA)作为5G通信技术的关键,具有重要的研究意义。它通过同时利用多个频段来提高数据传输速率、增加网络容量、优化用户体验,在移动通信领域具有巨大的应用潜力。文中探讨了5G载波聚合的基本原理,分析了其在不同应用场景下(如公园、商场、医院等)的具体应用,以评估CA技术在这些场景中的性能表现和优化效果。

关键词： 5G 载波聚合无线通信频谱效率性能提升

功率分流式PHEV车辆动力学模型与能量管理策略研究

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

小型内燃机与车辆技术 2024年第4期53卷 21-25页

作者：崔清章许昆朋上汽集团商用车技术中心上海200438

通过Matlab/Simulink软件建立了功率分流式PHEV车辆动力学仿真模型,并对各种工况下发动机、TM电机、ISG电机、电池的瞬时响应特性展开了研究,在此基础上提出了基于等效综合能耗最低的动力分配策略。计算结果表明:应用此动力分配策略选... 详细信息

通过Matlab/Simulink软件建立了功率分流式PHEV车辆动力学仿真模型,并对各种工况下发动机、TM电机、ISG电机、电池的瞬时响应特性展开了研究,在此基础上提出了基于等效综合能耗最低的动力分配策略。计算结果表明:应用此动力分配策略选取发动机、ISG电机、TM电机的最佳配合,整车的综合能耗率得到显著降低。

关键词： PHEV 功率分流综合能耗

ICP-AES法测定含铝预熔性渣洗料中钙、镁、硅、铝氧化物

在线全文

学校读者我要写书评

暂无评论

山西冶金 2024年第4期47卷 28-30页

作者：李青章常相征河北天柱钢铁集团技术中心河北唐山063000

研究使用电感耦合等离子体发射光谱法测定炼钢含铝预熔性渣洗料中钙、镁、硅、铝氧化物的分析条件以及处理样品的方式方法,为便于区别金属铝和三氧化二铝,创建了一种新型的仪器分析方法。由于试样中金属铝的存在,采用先酸溶再碱融的处... 详细信息

研究使用电感耦合等离子体发射光谱法测定炼钢含铝预熔性渣洗料中钙、镁、硅、铝氧化物的分析条件以及处理样品的方式方法,为便于区别金属铝和三氧化二铝,创建了一种新型的仪器分析方法。由于试样中金属铝的存在,采用先酸溶再碱融的处理方式,并采用配置相似基体的方法消除基体干扰。研究了渣洗料的溶样过程、仪器分析参数的选择、基体的干扰消除等对分析结果影响,在优化仪器分析参数和分解试样实验过程中,试样分析结果相对标准偏差远小于1.0%,分析结果准确度和精密度都很高。因此,该方法可取代化学分析法,是一种准确、快速的仪器分析方法。

关键词：电感耦合等离子发射光谱法含铝预熔性渣洗料金属铝钙、镁、硅、铝氧化物

基于MSPA-MCR模型与ROS理论的首都森林生态旅游区规划

在线全文

学校读者我要写书评

暂无评论

北京林业大学学报 2024年第10期46卷 112-124页

作者：李绍芃杜庆章宋跃朋李运远城乡生态环境北京实验室北京林业大学园林学院北京100083 林木育种与生态修复国家工程研究中心北京林业大学生物科学与技术学院北京100083

【目的】本研究旨在通过耦合分析提出科学的规划策略,以促进北京森林生态旅游区的生态保护和可持续发展。【方法】本研究以北京市延庆区张山营镇为例,采用形态学空间格局分析法识别生态源地,运用最小积累阻力模型识别生态廊道,并使用重... 详细信息

【目的】本研究旨在通过耦合分析提出科学的规划策略,以促进北京森林生态旅游区的生态保护和可持续发展。【方法】本研究以北京市延庆区张山营镇为例,采用形态学空间格局分析法识别生态源地,运用最小积累阻力模型识别生态廊道,并使用重力模型对廊道进行分级。同时,通过文献阅读和问卷调查确定研究区内影响游憩活动的自然、社会和现象因子,构建游憩机会谱并划分游憩分区。最后,耦合生态廊道与游憩分区的结果,提出针对不同游憩分区的具体规划策略。【结果】(1)研究区内生态源地面积147.19 km^(2),占比56%,识别出潜在生态廊道15条,总长度63.88 km。(2)生态源地主要分布在研究区北部林地,生态廊道联通西部与东部生态源地,对维护研究区生态环境发挥关键作用。(3)基于游憩机会谱划分出原生区、半原生区、介入区、自由区4类游憩分区,分别占比19.7%、40.9%、31.2%、8.2%。(4)根据上述结果,提出了针对不同游憩分区的具体森林生态旅游规划策略,包括群落植物配置、群落结构、生态廊道宽度、交通布局4方面。【结论】研究从生态保护和游客需求两个角度出发,强调应围绕重点区域进行多角度生态型保护开发。研究不仅丰富了生态旅游理论研究内容,还为森林生态旅游的可持续发展提供了实质性的理论指导和实践建议,有助于加快北京建设“生物多样性之都”的进程。

关键词：城市林业林下经济树种配置森林生态旅游形态学空间格局分析(MSPA) 游憩机会谱(ROS)

An Implementation for the Algorithm of Janet bases of Linear Differential Ideals in the Maple System

在线全文

学校读者我要写书评

暂无评论

Acta Mathematicae Applicatae Sinica 2004年第4期20卷 605-616页

作者： Shan-qingzhang Zhi-binLi DepartmentofComputerScience EastChinaNormalUniversityShanghai200062China

In this paper, an algorithm for computing the Janet bases of linear differential equations is described, which is the differential analogue of the algorithm JanetBasis improved by Gerdt. An implementation of the algorithm in Maple is given. The implemented algorithm includes some subalgorithms: Janet division, Pommaret division, the judgement of involutive divisor and reducible, the judgement of conventional divisor and reducible, involutive normal form and conventional normal form, involutive autoreduction and conventional autoreduction, PJ-autoreduction and so on. As an application, the Janet Bases of the determining system of classical Lie symmetries of some partial differential equations are obtained using our package.

关键词： Involutive bases Janet bases Grö bner bases symbolic computation and algebraic computation partial differential equations

Morphological responses to water-level fluctuations of two submerged macrophytes, Myriophyllum spicatum and Hydrilla verticillata

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Plant Ecology 2013年第1期6卷 64-70页

作者： Xiaoke Zhang Xueqin Liu qingzhang Ding Institute of Hydrobiology Chinese Academy of SciencesWuhan 430072China Graduate University of Chinese Academy of Sciences Beijing 100049China

Aims Myriophyllum spicatum and Hydrilla verticillata are common submerged macrophytes in the Yangtze River *** investigate their tolerances and adaptations to water-level fluctuations,an experiment was conducted in a *** We designed five different amplitudes of water-level fluctuations as static,615,630,660 and 690 cm during the 74 days of the *** each amplitude treatment,two cultivation methods were examined as monoculture and mixed *** Findings The results showed that *** had greater morphological responses to water-level fluctuations than *** amplitude had significant effects on branch number,shoot length and root dry weight(DW)of ***,whereas it only had significant effect on branch number of *** fluctuating amplitude and cultivation method had significant effects on total DW of ***,which was higher in monoculture than mixed *** total DW of *** was affected by fluctuating amplitude only,and the largest biomass was in the amplitude of 630 *** DW of *** was largest in the amplitude of 630 cm,high amplitude of water-level fluctuations would inhibit flowering and seed *** DW proportion was significantly affected by fluctuating amplitude and cultivation method in both species,and the root DW proportion of *** was significantly higher in the amplitude-of 690 *** conclude that moderate amplitude of water-level fluctuations can promote the distribution and growth of both species,and in order to accelerate the restoration of both species in natural habitats,the optimum amplitude should be keep at 615 to 630 cm.

关键词： Myriophyllum spicatum Hydrilla verticillata water-level fluctuations water regime adaptation

Integrating Parallelizing Compilation Technologies for SMP Clusters

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Computer Science & Technology 2005年第1期20卷 125-133页

作者： Xiao-BingFeng LiChen Yi-RanWang Xiao-MiAn LinMa Chun-LeiSang Zhao-qingzhang InstituteofComputingTechnology ChineseAcademyofSciencesBeijing100080P.R.China

In this paper, a source to source parallelizing complier system, AutoPar, ispresentd. The system transforms FORTRAN programs to multi-level hybrid MPI/OpenMP parallel *** parallel optimizing technologies, are utilized extensively to derive an effectiveprogram decomposition in the whole program scope. Other features such as synchronizationoptimization and communication optimization improve the performance scalability of the generatedparallel programs, from both intra-node and inter-node. The system makes great effort to boostautomation of parallelization. Profiling feedback is used in performance estimation which is thebasis of automatic program decomposition. Performance results for eight benchmarks in NPB1.0 fromNAS on an SMP cluster are given, and the speedup is desirable. It is noticeable that in theexperiment, at most one data distribution directive and a reduction directive are inserted by theuser in BT/SP/LU. The compiler is based on ORC, Open Research Compiler. ORC is a powerful compilerinfrastructure, with such features as robustness, flexibility and efficiency. Strong analysiscapability and well-defined infrastructure of ORC make the system implementation quite fast.

关键词： compiler optimization parallel system

An Energy Efficient MAC Protocol for Linear WSNs

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2015年第4期24卷 725-729页

作者： DAI Guoyong MIAO Chunyu YING Kezhen WANG Kai CHEN qingzhang College of Computer Science and Technology Zhejiang University of Technology College of Information Science and Technology Zhejiang Shuren University

Wireless sensor networks(WSNs) have been employed as an ideal solution in many applications for data gathering in harsh environment. Energy consumption is a key issue in wireless sensor networks since nodes are often battery operated. Medium access control(MAC) protocol plays an important role in energy efficiency in wireless sensor networks because nodes’ access to the shared medium is coordinated by the MAC layer. An energy efficient MAC protocol is designed for data gathering in linear wireless sensor networks. In order to enhance the performance, when a source node transmits data to the sink, proper relay nodes are selected for forwarding data according to the energy consumption factor and residual energy balance factor. Some simulation experiments are conducted and the results show that, the proposed protocol provides better energy efficiency and long lifetime than the existing DMAC protocol.

关键词： WSN Linear topology MAC protocol Low-energy consumption Relay nodes

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

计量确认在实验室中的实施与应用

理化检验（物理分册） 2024年第5期60卷 36-38页

作者：李青章王佳慧朱全河北天柱钢铁集团有限公司唐山063000

计量确认是保证测量设备能够符合预期使用要求的重要工作之一。对计量确认的定义、过程、方法等进行了分析。结果表明:计量确认工作能够确保测量设备的准确性和可靠性,从而确保生产过程中的质量控制。

关键词：计量确认实验室控制参数设备精度