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Supersonic flow onto solid wedges, multidimensional shock waves and free boundary problems Dedicated to Professor LI Ta Tsien on the Occasion of His 80th Birthday

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Science China Mathematics 2017年第8期60卷 1353-1370页

作者： chen gui-Qiang School of Mathematical Sciences Fudan University Academy of Mathematics and Systems Science Chinese Academy of Sciences School of Mathematical Sciences University of Chinese Academy of Sciences Mathematical Institute University of Oxford

When an upstream steady uniform supersonic flow impinges onto a symmetric straight-sided wedge,governed by the Euler equations,there are two possible steady oblique shock configurations if the wedge angle is less than the detachment angle—the steady weak shock with supersonic or subsonic downstream flow(determined by the wedge angle that is less than or greater than the sonic angle)and the steady strong shock with subsonic downstream flow,both of which satisfy the entropy *** fundamental issue—whether one or both of the steady weak and strong shocks are physically admissible solutions—has been vigorously debated over the past eight *** this paper,we survey some recent developments on the stability analysis of the steady shock solutions in both the steady and dynamic *** the static stability,we first show how the stability problem can be formulated as an initial-boundary value type problem and then reformulate it into a free boundary problem when the perturbation of both the upstream steady supersonic flow and the wedge boundary are suitably regular and small,and we finally present some recent results on the static stability of the steady supersonic and transonic *** the dynamic stability for potential flow,we first show how the stability problem can be formulated as an initial-boundary value problem and then use the self-similarity of the problem to reduce it into a boundary value problem and further reformulate it into a free boundary problem,and we finally survey some recent developments in solving this free boundary problem for the existence of the PrandtlMeyer configurations that tend to the steady weak supersonic or transonic oblique shock solutions as time goes to *** further developments and mathematical challenges in this direction are also discussed.

关键词： shock wave free boundary wedge problem transonic mixed type Euler equations static stability dynamic stability

十种热带园林植物废弃物青贮发酵品质和体外消化特征

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草地学报 2025年第1期33卷 283-288页

作者：陈婷吴硕符畅陈桂武农智颜字学娟李茂海南科技职业大学海南海口571126 海南大学热带农林学院海南儋州571737 中国热带农业科学院热带作物品种资源研究所海南儋州571737

本研究旨在探究热带园林植物废弃物的青贮发酵品质以及体外消化特征,为热带园林植物废弃物的饲料化利用提供参考。研究测定了朱槿(Hibiscus rosa-sinensis)、蓝花草(Ruellia simplex)、炮仗藤(Pyrostegia venusta)、茉莉花(Jasminum sam... 详细信息

本研究旨在探究热带园林植物废弃物的青贮发酵品质以及体外消化特征,为热带园林植物废弃物的饲料化利用提供参考。研究测定了朱槿(Hibiscus rosa-sinensis)、蓝花草(Ruellia simplex)、炮仗藤(Pyrostegia venusta)、茉莉花(Jasminum sambac)、朱蕉(Cordyline fruticosa)、基及树(Carmona microphylla)、红花羊蹄甲(Bauhinia×blakeana)、鱼尾葵(Caryota maxima)、三药槟榔(Areca triandra)和九里香(Murraya exotica)十种园林植物青贮30天后的发酵品质和体外消化特征。其中,炮仗藤青贮的粗蛋白含量最高为18.75%,三药槟榔青贮的pH值最低(3.40),朱槿的体外干物质消化率(72.44%)和产气量(55.95 mL)最高。综合青贮饲料营养成分、发酵品质指标和体外发酵数据评价热带园林植物废弃物的饲用价值次序为炮仗藤>朱槿>九里香>红花羊蹄甲>茉莉花>蓝花草>朱蕉>三药槟榔>鱼尾葵>基及树。

关键词：园林废弃物青贮品质体外消化饲用价值

同方期刊数据库博看期刊评论

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玉林市龙云灌区工程输水管道管材的比选

广西水利水电 2025年第1期 28-30+38页

作者：陈桂斌广西水利电力勘测设计研究院有限责任公司

本文旨在探讨龙云灌区管道管材的选择问题。通过分析不同地段的水力学条件、地基适应性及回填料要求，综合比较预应力钢筒混凝土管、球墨铸铁管、钢管等不同管材的技术性能、成本、耐用性、施工难度等因素，为龙云灌区工程提供科学合理... 详细信息

本文旨在探讨龙云灌区管道管材的选择问题。通过分析不同地段的水力学条件、地基适应性及回填料要求，综合比较预应力钢筒混凝土管、球墨铸铁管、钢管等不同管材的技术性能、成本、耐用性、施工难度等因素，为龙云灌区工程提供科学合理的管材选择方案。

关键词：输水管道预应力钢筒混凝土管球墨铸铁管钢管龙云灌区

Robust decentralized H_∞ control of multi-channel systems with norm-bounded parametric uncertainties

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Journal of Systems Engineering and Electronics 2007年第4期18卷 871-878页

作者： chen Ning gui Weihua School of Information Science and Engineering Central South Univ. Changsha 410083 P.R. China

A robust decentralized H∞ control problem for uncertain multi-channel systems is considered. The uncertainties are assumed to be time-invariant, norm-bounded, and exist in both the system and control input matrices. The dynamic output feedback is mainly dealt with. A necessary and sufficient condition for the uncertain multi-channel system to be stabilized robustly with a specified disturbance attenuation level is derived based on the bounded real lemma, which is reduced to a feasibility problem of a nonlinear matrix inequality （NMI）. A two-stage homotopy method is used to solve the NMI iteratively. First, a decentralized controller for the nominal system with no uncertainty is computed by imposing structural constraints on the coefficient matrices of the controller gradually. Then the decentralized controller is modified, again gradually, to cope with the uncertainties. On each stage, a variable is fixed alternately at the iterations to reduce the NMI to a linear matrix inequality （LMI）. A given example shows the efficiency of this method.

关键词： robust decentralized control parametric uncertainty homotopy method nonlinear matrix inequality LMI

基于MaxEnt模型的中国显齿蛇葡萄潜在适生区分析

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中国农业气象 2025年第2期46卷 213-225页

作者：周威钟艳雯陈玉贵李艳气象防灾减灾湖南省重点实验室长沙410118 湖南省气象服务中心长沙410118 湖南省气象信息中心长沙410118 中国气象局公共气象服务中心北京100081

基于中国显齿蛇葡萄现有193个地理分布数据和包括生物气候、海拔、辐射34个环境变量,利用最大熵模型(MaxEnt)模拟2041-2100年3种气候情景下显齿蛇葡萄潜在分布区及其变化,以期充分利用气候资源,为显齿蛇葡萄的种植、保护和产业发展等提... 详细信息

基于中国显齿蛇葡萄现有193个地理分布数据和包括生物气候、海拔、辐射34个环境变量,利用最大熵模型(MaxEnt)模拟2041-2100年3种气候情景下显齿蛇葡萄潜在分布区及其变化,以期充分利用气候资源,为显齿蛇葡萄的种植、保护和产业发展等提供科学参考。结果表明:(1)MaxEnt模型的模拟准确性较高,AUC值为0.928~0.956。(2)影响中国显齿蛇葡萄分布的6个关键环境因子为最干月降水量、最干季降水量、年降水量、5月月平均辐射、海拔和最冷月最低气温,高适生区的阈值分别为30~90mm、130~300mm、1600~2450mm、14000~15200KJ·m^(-2)·d^(-1)、<1100m和4.0~9.0℃。(3)可持续发展(SSP126)气候情景有利于增加显齿蛇葡萄的高、中适生区面积,2081-2100年显齿蛇葡萄适生区面积最大,为182.2万km^(2);局部发展(SSP245)气候情景下显齿蛇葡萄适生区面积增加效果低于可持续发展(SSP126)气候情景,但高于常规发展(SSP585)气候情景,主要表现在广东、广西、福建、云南和湖南的高适生区有所退化,四川东南部的中适生区增加;常规发展(SSP585)气候情景下,贵州、福建、广东和江西的部分高适生区逐步退化为中适生区,海南的中适生区退化为低适生区,全国的总适生区面积在2081-2100年为历史最低。(4)2041-2100年,显齿蛇葡萄总适生区面积仅在可持续发展(SSP126)气候情景下增加,在局部发展(SSP245)、常规发展(SSP585)气候情景下呈减少趋势;无论哪种气候情景,总适生区质心一致从目前的湖南、广西交界处向北略偏东方向移动46~80km至湖南省南部。

关键词：显齿蛇葡萄 MaxEnt模型适生区分析

新噪声污染防治法下的社会生活噪声污染监测实践

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中国标准化 2025年第3期 222-227页

作者：菅安琪陈桂淋江苏华测品标检测认证技术有限公司华测检测认证集团股份有限公司

随着社会发展,社会生活噪声逐渐成为了影响生活质量的突出问题,在有关的环境问题投诉中,社会生活噪声一直处在较高的投诉水平,给噪声监测及管理也带来较大的挑战。实践过程中,由于社会噪声复杂性,存在标准不适用、结果难以评价等问题,... 详细信息

随着社会发展,社会生活噪声逐渐成为了影响生活质量的突出问题,在有关的环境问题投诉中,社会生活噪声一直处在较高的投诉水平,给噪声监测及管理也带来较大的挑战。实践过程中,由于社会噪声复杂性,存在标准不适用、结果难以评价等问题,不利于噪声监测及管理工作开展。本文结合最新修订的《中华人民共和国噪声污染防治法》(2022年6月5日起施行),以电梯、变压器、水泵等设施噪声的监测与评价为实践案例,确立此类社会生活噪声的监测工作技术要点,为居民生活中的各类环境噪声污染纠纷问题的解决提供了技术方法。

关键词：噪声污染噪声监测社会生活噪声

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Delay-dependent decentralized H_∞ filtering for uncertain interconnected systems

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Journal of Systems Engineering and Electronics 2008年第4期19卷 766-774页

作者： chen Ning gui Weihua Zhang Xiaofeng School of Information Science and Engineering Central South Univ. Changsha 410083 P. R. China

This article considers delay dependent decentralized H∞ filtering for a class of uncertain interconnected systems, where the uncertainties are assumed to be time varying and satisfy the norm-bounded conditions. First, combining the Lyapunov-Krasovskii functional approach and the delay integral inequality of matrices, a sufficient condition of the existence of the robust decentralized H∞ filter is derived, which makes the error systems asymptotically stable and satisfies the H∞ norm of the transfer function from noise input to error output less than the specified up-bound on the basis of the form of uncertainties. Then, the above sufficient condition is transformed to a system of easily solvable LMIs via a series of equivalent transformation. Finally, the numerical simulation shows the efficiency of the main results.

关键词： interconnected systems H∞ filtering delay-dependent LMI.

Development and prospect of high-power Yb^(3+) doped fibers

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High Power Laser Science and Engineering 2018年第3期6卷 15-22页

作者： Yibo Wang gui chen Jinyan Li Wuhan National Laboratory for Optoelectronics Huazhong University of Science and Technology

Ytterbium-doped fibers have become the optimum gain media of high-power fiber lasers thanks to a simple energy structure, which strongly reduces the excited state absorption, and a low quantum defect and a high optic–optic conversion efficiency, which means the low thermal load. In this paper, we take a review of the current state of the art in terms of Yb^(3+)doped fibers for high-power fiber lasers, including the development of the fabrication techniques. The research work to overcome the challenges for Yb3+doped fibers, which affect the stability of output power and beam quality, will be demonstrated. Direction of further research is presented and the goal is to look for a fiber design, to boost single fiber output power, stabilize the laser power and support robust single-mode operation.

关键词： fiber laser and applications optical material

Design of a fully differential CMOS LNA for 3.1–10.6 GHz UWB communication systems

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The Journal of China Universities of Posts and Telecommunications 2008年第4期15卷 107-111页

作者： ZHANG Hong chen gui-can Institute of Microelectronics Xi'an Jiaotong University Xi'an 710049 China

A fully differential complementary metal oxide semiconductor （CMOS） low noise amplifier （LNA） for 3.1-10.6 GHz ultra-wideband （UWB） communication systems is presented. The LNA adopts capacitive cross-coupling common-gate （CG） topology to achieve wideband input matching and low noise figure （NF）. Inductive series-peaking is used for the LNA to obtain broadband flat gain in the whole 3.1-10.6 GHz band. Designed in 0.18 um CMOS technology, the LNA achieves an NF of 3.1-4.7 dB, an Sll of less than -10 dB, an S21 of 10.3 dB with ±0.4 dB fluctuation, and an input 3rd interception point （IIP3） of -5.1 dBm, while the current consumption is only 4.8 mA from a 1.8 V power supply. The chip area of the LNA is 1×0.94 mm^2.

关键词： LNA common gate capacitive cross coupling series peaking UWB