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Historical tillage promotes grass-legume mixtures establishment and accelerates soil microbial activity and organic carbon decomposition

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Journal of Arid Land 2024年第7期16卷 910-924页

作者： ZHOU Jiqiong GONG Jinchao WANG Pengsen SU Yingying LI Xuxu LI Xiangjun LIU Lin BAI Yanfu MA Congyu WANG Wen HUANG Ting YAN Yanhong zhang xinquan Department of Grassland Science College of Grassland Science&TechnologySichuan Agricultural UniversityChengdu 611130China Yunnan Sheep Breeding and Extension Center Kunming 655204China

Perennial grass-legume mixtures have been extensively used to restore degraded grasslands,increasing grassland productivity and forage *** is crucial for seedbed preparation and sustainable weed management for the establishment of grass-legume ***,a common concern is that intensive tillage may alter soil characteristics,leading to losses in soil organic carbon(SOC).We investigated the plant community composition,SOC,soil microbial biomass carbon(MBC),soil enzyme activities,and soil properties in long-term perennial grass-legume mixtures under two different tillage intensities(once and twice)as well as in a fenced grassland(FG).The establishment of grass-legume mixtures increased plant species diversity and plant community coverage,compared with *** with once tilled grassland(OTG),twice tilled grassland(TTG)enhanced the coverage of high-quality leguminous forage species by 380.3%.Grass-legume mixtures with historical tillage decreased SOC and dissolved organic carbon(DOC)concentrations,whereas soil MBC concentrations in OTG and TTG increased by 16.0%and 16.4%,respectively,compared with *** significantly decreased the activity of N-acetyl-β-D-glucosaminidase(NAG)by 72.3%,whereas soil enzymeβ-glucosidase(βG)in OTG and TTG increased by 55.9%and 27.3%,respectively,compared with *** analysis indicated a close association of the increase in MBC andβG activities with the rapid decline in *** result suggested that MBC was a key driving factor in soil carbon storage dynamics,potentially accelerating soil carbon cycling and facilitating biogeochemical *** establishment of grass-legume mixtures effectively improves forage quality and boosts plant diversity,thereby facilitating the restoration of degraded *** tillage assists in establishing legume-grass mixtures by controlling weeds,it accelerates microbial activity and organic carbon *** findings provide a foundation for understanding the

关键词： tillage grass-legume mixtures fencing grassland microbial biomass carbon β-glucosidase(βG) N-acetyl-β-D-glucosaminidase(NAG)

渗透各向异性土层中考虑挡墙厚度的基坑稳态渗流解析解

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铁道学报 2024年第5期46卷 142-151页

作者：余俊李东凯和振张志中张鑫全中南大学土木工程学院湖南长沙410075 中铁城建集团有限公司总承包分公司湖南长沙410000

本文对考虑厚度挡墙支护下渗透各向异性土层中基坑的二维稳态渗流进行了解析研究。根据对称性取基坑半截面,将周围土层划分为5个规则区域,采用坐标变换将渗透各向异性土层转换成等效各向同性土层,对各区域利用叠加法和分离变量法推导得... 详细信息

本文对考虑厚度挡墙支护下渗透各向异性土层中基坑的二维稳态渗流进行了解析研究。根据对称性取基坑半截面,将周围土层划分为5个规则区域,采用坐标变换将渗透各向异性土层转换成等效各向同性土层,对各区域利用叠加法和分离变量法推导得到二维稳态渗流场、挡墙上水压力以及坑底出逸比降的显式解析解。对比保角变换和积分变换方法,本文解渗流场计算结果连续且无奇异点,且基坑水头和挡墙两侧水压力分布情况与数值软件分析一致性较好,说明本文解析解的正确性和优越性。本文解与不同计算方法得到的挡墙水压力结果对比分析发现,挡墙厚度d、竖直与水平向渗透系数比α对挡墙上水压力的影响不可忽略。分析α、d对挡墙底部水压力及出逸比降的影响,随着α和d的增大,基坑外侧挡墙底部水压力增大,基坑内侧挡墙底部水压力减小;随着α和d的逐渐减小,坑底出逸比降不断增大;当α和d较小时,考虑一维渗流情况得到的出逸比降安全性较低,且随着α和d的减小与本文解析解差距越来越大。

关键词：二维稳态渗流渗透各向异性显式解析解考虑厚度的挡墙总水头分布出逸比降水压力

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增氧条件下粉绿狐尾藻的氮磷吸收特征

农业工程学报 2024年第3期40卷 271-282页

作者：张文萍蒋易张鑫全文清柏李汉常谭歆王润贤湖南农业大学水利与土木工程学院长沙410128 中铁城建集团有限公司长沙410208 湖南省欧阳海灌区水利水电工程管理局耒阳421800

为探明增氧处理下粉绿狐尾藻植株的氮磷吸收特征,该研究以粉绿狐尾藻为研究材料,设置5个不同增氧水平(增氧时长),即CK (0 min)、JO1(4 min)、JO_(2)(6 min)、JO3(8 min)、JO4(10 min),系统分析了不同增氧水平下粉绿狐尾藻幼苗期(7月10日... 详细信息

为探明增氧处理下粉绿狐尾藻植株的氮磷吸收特征,该研究以粉绿狐尾藻为研究材料,设置5个不同增氧水平(增氧时长),即CK (0 min)、JO1(4 min)、JO_(2)(6 min)、JO3(8 min)、JO4(10 min),系统分析了不同增氧水平下粉绿狐尾藻幼苗期(7月10日—9月15日)、生长旺盛期(9月16日—12月22日)生理指标的变化规律,明确了植株N、P含量、N/P和叶绿素含量、底泥各形态氮磷含量之间的关系。结果表明:增氧8 min时,t_(1)、t_(2)取样时期(9月15日、10月10日)粉绿狐尾藻的氮、磷吸收量及t5取样时期(12月22日)的氮吸收量最高;增氧6 min时,t_(3)、t4取样时期(10月27日、11月16日)粉绿狐尾藻的氮、磷吸收量及t5取样时期的磷吸收量最高;增氧有利于粉绿狐尾藻在t_(1)、t_(2)、t_(3)时期对氮的吸收,t4时期对磷的吸收,表现为t_(1)、t_(2)、t_(3)时期粉绿狐尾藻的植株氮磷比分别增加5.27%~36.57%、9.04%~63.07%、3.50%~73.45%,t4时期的N/P降低1.38%-34.05%;增氧使t_(2)、t5时期粉绿狐尾藻叶片叶绿素a、b及叶绿素总含量降低,t4时期叶绿素含量增加同时,使t_(1)、t_(2)时期底泥氮磷比值(sediment total nitrogen/phosphorus,STN/P)分别降低64.84%、54.76%,t4、t5时期STN/P分别增高138.97%、47.02%;层次聚类分析及多元线性回归分析结果进一步表明,增氧6 min是增氧促进粉绿狐尾藻氮磷吸收利用的理论满意方案,增氧降低t_(1)时期叶绿素a、b含量、t5时期底泥碱解氮含量(sediment alkali-hydro nitrogen,SAHN)和t4时期铁结合态磷(Fe-P)含量同时,促进了粉绿狐尾藻t5时期氮磷的吸收。增氧调控粉绿狐尾藻叶片叶绿素形成和底泥氮磷的形态转化,促进其对底泥氮磷吸收,同时提高了粉绿狐尾藻氮磷的吸收利用效果,可抑制甲烷和氧化亚氮、CO_(2)等温室气体的排放。

关键词：氮磷植株氮磷比氮磷形态增氧处理粉绿狐尾藻

Guaranteed cost control and anti-windup design of saturated switched systems

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Journal of Control and Decision 2023年第2期10卷 293-299页

作者： xinquan zhang Jianlin Wang School of Information and Control Engineering Liaoning Petrochemical UniversityFushunPeople’s Republic of China

In this paper,the problem of guaranteed cost control and anti-windup design is studied for a class of switched systems with actuator *** switching strategy and anti-windup compensator are designed to ensure the asymptotic stability of the closed-loop system and to obtain the minimum upper bound of the cost *** sufficient conditions for the existence of an anti-windup compensator of guaranteed cost are given by using the multiple Lyapunov functions *** this basis,the minimum upper bound of the cost function is determined by solving the optimisation problem under the constraint of linear matrix inequality(LMI).Finally,a numerical example is given to verify the effectiveness of the proposed method.

关键词： Guaranteed cost control switched systems with actuator saturation anti-windup multiple Lyapunov functions LMI

Non-fragile stabilisation of nonlinear switched systems with actuator saturation

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Journal of Control and Decision 2023年第2期10卷 260-269页

作者： Jianlin Wang xinquan zhang School of Information and Control Engineering Liaoning Petrochemical UniversityFushunPeople’s Republic of China

For nonlinear continuous-time switched systems,the problem ofhowto overcome the controller vulnerability is studied when the saturating actuator is *** sufficient condition of non-fragile stabilisation of the system is derived by using the method of multiple Lyapunov ***,a switching law and the non-fragile state feedback controllers are designed such that the closed-loop system can be asymptotically stabilised at the ***,when some scalar parameters of the closed-loop system are given,the design issue of the non-fragile state feedback controllers and the switching law,which aim at enlarging the estimation of domain of attraction for closed-loop system,is transformed into a convex optimisation issue with linear matrix inequalities(LMI)constraints,and a numerical example is given to verify the effectiveness of the proposed method.

关键词： Actuator saturation nonlinear switched systems non-fragile multiple Lyapunov functions LMI

Profile Compensation for Single-Point Diamond Turning of Microlens Array

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Nanomanufacturing and Metrology 2022年第4期5卷 403-411页

作者： Zhiyue Wang Zaozao Chen xinquan zhang National Key Laboratory of Science and Technology on Micro/Nano Fabrication Shanghai Jiao Tong UniversityShanghai200240China School of Mechanical Engineering Shanghai Jiao Tong UniversityShanghai200240China

To improve the efficiency and consistency of machined microlens array using single-point diamond turning technology,a theoretical model of surface form error is proposed in this ***,a compensation method for this model is *** the proposed tool equivalent tilt angle model,the microlens array is regarded as a freeform *** corresponding curvature radius of the surface at each cutting point along the cutting direction is calculated by establishing a slow slide servo cutting *** the spatial form error model,the assumption is that surface form error has a linear relationship with z-axis maximum speed *** empirical linear equation is obtained and verified,with a maximum deviation of 0.4μ***,after machining,the surface form error is measured and processed using on-machine *** theoretical and measured surface form errors are *** surface form error is compensated in the machining *** peak-to-valley value is reduced from 5.4 to 0.6μm after *** show that the single-point diamond turning and compensation method for the microlens array presented in this paper can predict the surface form error and significantly improve machining accuracy and consistency.

关键词： Microlens array Single-point diamond turning Slow slide servo On-machine measurement Compensation

Stability analysis and antiwindup design of uncertain discrete-time switched linear systems subject to actuator saturation

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控制理论与应用（英文版） 2012年第3期10卷 325-331页

作者： xinquan zhang Mingshun WANG Jun ZHAO State Key Laboratory of Synthetical Automation for Process Industries Northeastern UniversityShenyang Liaoning 110819China

This paper investigates the stability analysis and antiwindup design problem for a class of discrete-time switched linear systems with time-varying norm-bounded uncertainties and saturating actuators by using the switched Lyapunov function approach. Supposing that a set of linear dynamic output controllers have been designed to stabilize the switched system without considering its input saturation, we design antiwindup compensation gains in order to enlarge the domain of attraction of the closed-loop system in the presence of saturation. Then, in terms of a sector condition, the antiwindup compensation gains which aim to maximize the estimation of domain of attraction of the closed-loop system are presented by solving a convex optimization problem with linear matrix inequality （LMI） constraints. A numerical example is given to demonstrate the effectiveness of the proposed design method.

关键词： Antiwindup Switched systems Saturating actuators Switched Lyapunov function Attraction domain LMI

Plant Community Characteristics of Trampling Disturbance Kobresia humilis Community along the Road in Naqu,Tibet

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Wuhan University Journal of Natural Sciences 2006年第4期11卷 1035-1040页

作者： zhang Jinhua LIU Shuzhe zhang xinquan YAN Yan zhang Jianguo Institute of Mountain Hazards and Environment Chinese Academy of Science Chengdu 610041 Sichuan China College of Animal Science and Technology Sichuan AgriculturalUniversity Ya＇an 625014 Sichuan China

The change of plant community character during recovery succession processes of high mountain meadow in Naqu, Tibet, was investigated. The results show that there are 41 plant species in the inventoried quadrates. The high-plants in four big families plays important roles in natural vegetation recovery, while Kobresia play an important role in climax communities. The plant species components changed with each succession stage. The plant species were mainly annual and biennial during the early succession stage, and perennial during the medium; and dominated by Kobresia humilis during the late. Potentilla bifurca and Potentilla tanaletfolia were both found in all stages. The accumulated number of family, genus, and species during the succession process varied quadric with the stages. The main plant community characteristics varied logistically with the succession stages except the height. The community characteristics mainly affected by dominant species which were changed in same rhythms. The biomass under ground was far more than the upground. The plant diversity inflated in the medium stage.

关键词： plant community characteristics alpine meadow trampling disturbance Tibet

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五峰山长江大桥南锚碇倾斜基岩地质条件分析

铁道勘察 2024年第1期50卷 47-53页

作者：李守明张鑫全王猛曾洪贤中铁大桥勘测设计院集团有限公司武汉430056

五峰山长江大桥南锚碇位于五峰山山壑间,采用圆形扩大基础,外径90 m,场地内地形变化大,岩土层分布复杂,合理设置适应于地质条件的锚碇基础方案,对工程安全性、经济性意义重大。为了充分利用南锚碇场地内工程性能良好的微风化凝灰质砂岩... 详细信息

五峰山长江大桥南锚碇位于五峰山山壑间,采用圆形扩大基础,外径90 m,场地内地形变化大,岩土层分布复杂,合理设置适应于地质条件的锚碇基础方案,对工程安全性、经济性意义重大。为了充分利用南锚碇场地内工程性能良好的微风化凝灰质砂岩地基,准确评价岩土体稳定性及对工程的适宜性,采用了露头调查、钻探、物探、原位测试及室内试验的综合勘察手段。基于地质成因分析及赤平投影方法,发现岩面、风化面总体产状具有一致性,倾角约18°,沿倾斜方向分布较稳定;通过进一步分析倾斜岩体及其风化面分布与锚碇基坑的相互作用关系,评价采用台阶式基础方案的可行性,并分析了其对岩石地基的利用优势,针对性提出了锚碇基坑的施工建议。经优化,考虑倾斜基岩工程地质条件的锚碇基础设计可减少约4万m3的微风化岩石开挖量,使工程兼具安全性与经济性。

关键词：高速铁路五峰山长江大桥工程地质倾斜岩层重力式锚碇稳定性