检索结果-南通市图书馆

Analytical Models of Passive Linear Structures in Printed Circuit Boards

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2021年第2期30卷 275-281页

作者： PENG Zhenzhen SU donglin The School of Electronic and Information Engineering Beihang University The Research Institute for Frontier Science Beihang University

Analytical models for passive linear structures, like metallic traces, vias, are proposed for simulations at the package and Printed circuit board(PCB) levels. In the proposed method, traces are modeled based on the transmission line theory, whereas the vias are described by the parallel-plate impedance and several equivalent circuits elements. The proposed models can be applied to efficiently simulate composed passive linear structures. Several scenarios are analyzed including traces with two or three width, traces routed into different layers and interconnects commonly used in PCBs. The results of the models are compared with those from the fullwave simulations and experiments. An improvement on the computation speed has been observed with respect to the full-wave simulations at the effective range of models. In our measurements, a compensation approach of impedance mismatch in parameter measurements is analyzed and calculated, which could significantly simplify the experimental process.

关键词： transmission line theory passive linear structures equivalent circuit elements full-wave simulations interconnection compensation approach parallel-plate impedance printed circuit interconnections metallic traces passive networks impedance matching equivalent circuits printed circuit boards PCB compensation analytical models impedance mismatching

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

高速飞行器气动光学效应

中山大学学报（自然科学版）（中英文） 2025年第1期64卷 257-264页

作者：田立丰杨东霖黄开诱中山大学航空航天学院广东深圳518107 深圳市智能微小卫星星座技术与应用重点实验室广东深圳518107

采用数值模拟、计算光学方法和理论,对超声速飞行器流场进行数值模拟研究,获取不同飞行高度和攻角下光学窗口上方流场的密度分布,根据Gladstone-Dale关系得到光学窗口上方的折射率场,利用光线追迹法计算流场光程差分布情况。对流场光程... 详细信息

采用数值模拟、计算光学方法和理论,对超声速飞行器流场进行数值模拟研究,获取不同飞行高度和攻角下光学窗口上方流场的密度分布,根据Gladstone-Dale关系得到光学窗口上方的折射率场,利用光线追迹法计算流场光程差分布情况。对流场光程差的分布情况进行分析,可以得出结论:随着飞行高度的增加,气动光学效应逐渐减弱;随着攻角的增大,气动光学效应逐渐增强。

关键词：气动光学飞行高度攻角光程差

乡村经济韧性与耕地破碎度空间格局及耦合关系研究——以重庆市奉节县为例

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

西南大学学报（自然科学版） 2025年第1期47卷 15-30页

作者：李东麟杨胜强廖和平西南大学地理科学学院/西南大学精准扶贫与区域发展评估研究中心重庆400715

耕地破碎严重制约了乡村经济发展。探究乡村经济韧性与耕地破碎度之间的关系,对乡村振兴和土地整治策略制定有重要指导意义。本研究以重庆市奉节县60个村庄为研究对象,综合运用“压力—状态—响应”模型与熵权-TOPSIS法,探究奉节县乡村... 详细信息

耕地破碎严重制约了乡村经济发展。探究乡村经济韧性与耕地破碎度之间的关系,对乡村振兴和土地整治策略制定有重要指导意义。本研究以重庆市奉节县60个村庄为研究对象,综合运用“压力—状态—响应”模型与熵权-TOPSIS法,探究奉节县乡村经济韧性和耕地破碎度的空间格局及二者之间的耦合协调关系。研究发现:①高经济韧性乡村在长江以北围绕奉节县城集聚分布,在长江以南零星分布;②高破碎度耕地呈“一心两翼”格局,奉节县中部和南北两端耕地破碎度较高;③乡村经济韧性与耕地破碎度之间耦合协调度以适度协调和初级协调为主,乡村经济发展处于过渡阶段;④地理加权回归分析显示奉节县西北部乡村耕地破碎度与乡村经济韧性之间呈显著负相关,耕地破碎度越高,乡村经济韧性越低。

关键词：乡村经济韧性耕地破碎空间格局耦合协调地理加权回归

An Algorithm for Output Spectrum Analysis of Nonlinear System with Correlative Sources Based on Power Series

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2021年第3期30卷 542-548页

作者： XU Hui SU donglin The School of Electronic and Information Engineering Beihang University The Research Institute for Frontier Science Beihang University

An algorithm for output spectrum analysis of nonlinear system with correlative sources is ***, the output terms of nonlinear system are analyzed based on the power series. Then, the algorithm is proposed. In the proposed method, different terms with the same frequency are picked out and added together by considering different phases, and the amplitudes of the output spectrum are obtained from the summarized results. Two numerical examples are used to verify the proposed algorithm. It is found that the amplitudes of output spectrum vary with different combinations of phases. Finally, the proposed algorithm is applied to control the output spectrum. Results show that the output amplitude of a specific frequency can be suppressed through changing both the amplitudes and the phases of the input signals.

关键词： output amplitude correlative sources output spectrum analysis spectral analysis nonlinear system power series

Comparison of a Very-fine-resolution GCM with RCM Dynamical Downscaling in Simulating Climate in China

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2016年第5期33卷 559-570页

作者： donglin GUO Huijun WANG Nansen-Zhu International Research Center Institute of Atmospheric Physics Chinese Academy of Sciences Climate Change Research Center Chinese Academy of Sciences Collaborative Innovation Center on Forecast and Evaluation of Meteorological disasters Nanjing University of Information Science & Technology

Regional climate simulation can generally be improved by using an RCM nested within a coarser-resolution ***, whether or not it can also be improved by the direct use of a state-of-the-art GCM with very fine resolution, close to that of an RCM, and, if so, which is the better approach, are open questions. These questions are important for understanding and using these two kinds of simulation approaches, but have not yet been investigated. Accordingly, the present reported work compared simulation results over China from a very-fine-resolution GCM（VFRGCM） and from RCM dynamical downscaling. The results showed that：（1） The VFRGCM reproduces the climatologies and trends of both air temperature and precipitation, as well as inter-monthly variations of air temperature in terms of spatial pattern and amount, closer to observations than the coarse-resolution version of the GCM. This is not the case, however, for the inter-monthly variations of precipitation.（2） The VFRGCM captures the climatology, trend, and inter-monthly variation of air temperature, as well as the trend in precipitation, more reasonably than the RCM dynamical downscaling method.（3） The RCM dynamical downscaling method performs better than the VFRGCM in terms of the climatology and inter-monthly variation of precipitation. Overall,the results suggest that VFRGCMs possess great potential with regard to their application in climate simulation in the future,and the RCM dynamical downscaling method is still dominant in terms of regional precipitation simulation.

关键词： climate simulation dynamical downscaling GCM RCM

Simulated effect of soil freeze-thaw process on surface hydrologic and thermal fluxes in frozen ground region of the Northern Hemisphere

在线全文

学校读者我要写书评

暂无评论

Research in Cold and Arid Regions 2021年第1期13卷 18-29页

作者： di Ma SiQiong Luo donglin Guo ShiHua Lyu XianHong Meng BoLi Chen LiHui Luo Key Laboratory for Land Surface Process and Climate Change in Cold and Arid Regions Northwest Institute of Eco-Environment and ResourcesChinese Academy of ScienceLanzhouGansu 730000China College of Atmospheric Sciences Lanzhou UniversityLanzhouGansu 730000China Nansen-Zhu International Research Center Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China School of Atmospheric Sciences Plateau Atmosphere and Environment Key Laboratory of Sichuan ProvinceChengdu University of Information TechnologyChengduSichuan 610225China Changzhou Meteorological Bureau ChangzhouJiangsu 213000China State Key Laboratory of Frozen Soils Engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhouGansu 730000China

Soil freeze-thaw process is closely related to surface energy budget,hydrological activity,and terrestrial *** this study,two numerical experiments(including and excluding soil freeze-thaw process)were designed to examine the effect of soil freeze-thaw process on surface hydrologic and thermal fluxes in frozen ground region in the Northern Hemisphere based on the state-of-the-art Community Earth System Model version *** show that in response to soil freeze-thaw process,the area averaged soil temperature in the shallow layer(0.0175−0.0451 m)decreases by 0.35℃in the TP(Tibetan Plateau),0.69℃in CES(Central and Eastern Siberia),and 0.6℃in NA(North America)during summer,and increases by 1.93℃in the TP,2.28℃in CES and 1.61℃in NA during winter,***,in response to soil freeze-thaw process,the area averaged soil liquid water content increases in summer and decrease in *** surface heat flux components,the ground heat flux is most significantly affected by the freeze-thaw process in both summer and winter,followed by sensible heat flux and latent heat flux in *** the TP area,the ground heat flux increases by 2.82 W/m2(28.5%)in summer and decreases by 3.63 W/m2(40%)in ***,in CES,the ground heat flux increases by 1.89 W/m2(11.3%)in summer and decreases by 1.41 W/m2(18.6%)in *** heat fluxes in the Tibetan Plateau are more susceptible to the freeze-thaw process compared with the high-latitude frozen soil *** freeze-thaw process can induce significant warming in the Tibetan Plateau in ***,this process induces significant cooling in high-latitude regions in *** frozen ground can prevent soil liquid water from infiltrating to deep soil layers at the beginning of thawing;however,as the frozen ground thaws continuously,the infiltration of the liquid water increases and the deep soil can store water like a sponge,accompanied by decreasing surface *** influence of the soil freeze-thaw pr

关键词： freeze-thaw effect hydrologic and thermal frozen ground Northern Hemisphere

Realization of Interpersonal Function of Euphemism from Perspective of Fuzzy Linguistics

在线全文

学校读者我要写书评

暂无评论

学术界 2015年第8期 288-293页

作者： Feng donglin Department of College Foreign Languages Studies Tianjin University of Commerce Tianjin 300134

Euphemisms are widely employed in every aspect of social life. The analysis is made on the realization of interpersonal function of euphemism as a fuzzy language on the basis of discussion on the relationship between euphemism and fuzzy linguistics. It is hoped that the analysis can enrich and perfect the current research on euphemism so that the readers can have a general picture of euphemism and employ euphemisms more precisely and properly in communication. By so doing,the communication can be smoother and the objective of communication can be better achieved.

关键词：语言学模糊社会生活通信

Adaptive support vector machine decision feedback equalizer

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2011年第3期22卷 452-461页

作者： Sumin Zhang Shu Li donglin Su School of Electronic and Information Engineering Beihang UniversityBeijing 100191P.R.China The 54th Institute of China Electronics Technology Group Corporation Shijiazhuang 050081P.R.China nstitute of Land-air Defense Equipment Beijing 100085P.R.China

An adaptive support vector machine decision feedback equalizer（ASVM-DFE） based on the least square support vector machine（LS-SVM） is proposed,it solves linear system iteratively with less computational *** adaptive non-singleton fuzzy support vector machine decision feedback equalizer（ANSFSVMDFE） is also presented,it adopts the non-singleton fuzzy Gaussian kernel function with similar characteristic of pre-filter and is modified with a space transformation based *** under nonlinear time variant channels show that ASVM-DFE and ANSFSVM-DFE perform very well on nonlinear equalization and ANSFSVM-DFE acts especially well in resisting abrupt interference.

关键词： non-singleton fuzzy system support vector machine(SVM) equalizer decision feedback.

The long-term trend of Bohai Sea ice in different emission scenarios

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2021年第7期40卷 100-118页

作者： donglin Guo Rui Li Peng Zhao College of Oceanic and Atmospheric Sciences Ocean University of ChinaQingdao 266100China North China Sea Marine Forecasting Center Ministry of Natural ResourcesQingdao 266061China

Based on a coupled ocean-sea ice model,this study investigates how changes in the mean state of the atmosphere in different CO2 emission scenarios (RCP 8.5,6.0,4.5 and 2.6) may affect the sea ice in the Bohai Sea,China,especially in the Liaodong Bay,the largest bay in the Bohai Sea. In the RCP 8.5 scenario,an abrupt change of the atmospheric state happens around 2070. Due to the abrupt change,wintertime sea ice of the Liaodong Bay can be divided into 3 periods: a mild decreasing period (2021–2060),in which the sea ice severity weakens at a near-constant rate;a rapid decreasing period (2061–2080),in which the sea ice severity drops dramatically;and a stabilized period (2081–2100). During 2021–2060,the dates of first ice are approximately unchanged,suggesting that the onset of sea ice is probably determined by a cold-air event and is not sensitive to the mean state of the atmosphere. The mean and maximum sea ice thickness in the Liaodong Bay is relatively stable before 2060,and then drops rapidly in the following decade. different from the RCP 8.5 scenario,atmospheric state changes smoothly in the RCP 6.0,4.5 and 2.6 scenarios. In the RCP 6.0 scenario,the sea ice severity in the Bohai Sea weakens with time to the end of the twenty-first century. In the RCP 4.5 scenario,the sea ice severity weakens with time until reaching a stable state around the 2070s. In the RCP 2.6 scenario,the sea ice severity weakens until the 2040s,stabilizes from then,and starts intensifying after the 2080s. The sea ice condition in the other bays of the Bohai Sea is also discussed under the four CO_(2) emissions scenarios. Among atmospheric factors,air temperature is the leading one for the decline of the sea ice extent. Specific humidity also plays an important role in the four scenarios. The surface downward shortwave/longwave radiation and meridional wind only matter in certain scenarios,while effects from the zonal wind and precipitation are negligible.

关键词： sea ice Liaodong Bay RCP scenarios NEMO LIM2