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Design of optimal trajectory transition controller for thrust-vectored V/STOL aircraft

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Science China(Information Sciences) 2021年第3期64卷 235-237页

作者： zhiqiang cheng Jihong ZHU Xiaming YUAN Xiangyang WANG Department of Computer Science and Technology Tsinghua University Key Laboratory of Complex Ship System Simulation

Dear editor,In recent years, vertical and/or short take-off and landing(V/STOL) aircraft have attracted much attention because they combine the efficiency of fixed-wing vehicles with the flexibility of traditional ver... 详细信息

关键词： backward propagation V/STOL transition control thrust-vector optimal trajectory

A NEW EXPLICIT SIMULATION FOR MOULD FILLING WITH HIGH VISCOUS FEEDSTOCK

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Acta Mechanica Solida Sinica 2004年第4期17卷 347-352页

作者： cheng zhiqiang Barriere Thierry Liu Baosheng Gelin Jean Claude Department of Applied Mechanics Southwest Jiaotong UniversityChengdu 610031China LMARC University of Franche-Comte and CNRS24 Chemin de l’′epitapheBesancon 25000France

In the simulation of the metal injection moulding (MIM), the behaviours of feedstock are much di?erent from which of the polymer injection. It is a mixture of the metallic powder in high concentration and some plastic binder. The advance in simulation of the mould ?lling with such high viscous feedstock is featured by the development of a fully explicit vectorial algorithm. On the basis of previous explicit software realized by the authors, the new algorithm avoids the global solution for pressure ?elds and the use of MINI elements to improve its e?ciency. Except for the operations at element level, neither global solution nor the construction of global matrix is required in simulation. A special strategy is used to regulate the incompressibility condition in ?lled domain at each time step. In case of the MIM problems, this method provides a fast way to simulate the ?lling processes. The computational cost is about linearly proportional to the degree of freedom number. Moreover, this vectorial algorithm can be easily parallelized for high performance computation with multi-clusters. The comparison of numerical results with previous simulations on 3D cases proves the validity and e?ciency of new algorithm.

关键词： mould filling high viscosity explicit simulation vectorial algorithm

Biofumigation effects of brassicaceous cover crops on soil health in cucurbit agroecosystems in Hawaii, USA

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Pedosphere 2022年第4期32卷 521-531页

作者： Philip WAISEN zhiqiang cheng Brent S.SIPES Koon-Hui WANG Department of Plant and Environmental Protection Sciences University of Hawaii at ManoaHI 96822USA Department of Agriculture Papua New Guinea University of TechnologyLae 411Papua New Guinea University of California Agriculture and Natural Resources Division Cooperative ExtensionIndio CA 92201USA

Brassicaceous cover crops, such as brown mustard (Brassica juncea) and oil radish (Raphanus sativus), are commonly used for biofumigation, a process that utilizes isothiocyanates (ITCs) generated from the hydrolysis of glucosinolates in Brassica plants to suppress soil-borne pathogens, including plant-parasitic nematodes. Given the biocidal nature of ITCs, limited information is available on the non-target effects of biofumigation on free-living nematodes, which are reliable soil health indicators. The objectives of this study were to determine if biofumigation methods effective against plant-parasitic nematodes would have non-target effects on free-living nematodes, and to examine the relationships between biofumigation indicators and nematode communities. Three field trials were conducted to examine whether different biofumigation methods would affect free-living nematodes. Tissue maceration of biofumigant crops, soil tillage, and black plastic mulching were adopted singly or in combination to generate different regimes of biofumigation efficacy. Termination of biofumigant crops by tissue maceration and soil tillage followed by black plastic mulching for one week was most effective in suppressing plant-parasitic nematodes and enhancing bacterial decomposition. However, these effects did not last through the subsequent zucchini (Cucurbita pepo) crop cycle. When comparing changes in soil glucose and sulfate concentrations as indicators of biofumigation efficacy, we found that soil sulfate was a better indicator of biofumigation efficacy than soil glucose, owing to the more stable state of sulfate in soil. Canonical correspondence analysis between soil sulfate as a biofumigation indicator and nematode soil health indicators revealed strong positive correlations of sulfate level with the abundances of bacterivorous and carnivorous nematodes, enrichment index, brown mustard biomass, and soil temperature. However, biofumigation did not affect the nematode community stru

关键词： brown mustard free-living nematode glucose oil radish plant-parasitic nematode soil-borne pathogens sulfate

Elevational distribution of forests and its spatiotemporal dynamics in subtropical China from 2000 to 2019

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Science China Earth Sciences 2024年第8期67卷 2563-2582页

作者： Zhencan ZHENG Liuwen ZHUANG Guofang MIAO Han LIU zhiqiang cheng Wenyu LI Rong SHANG Peng GONG Jing Ming CHEN Institute of Geography Fujian Normal University Key Laboratory of Humid Subtropical Eco-Geographical Process (Ministry of Education) Fujian Normal University School of Geographical Sciences Fujian Normal University National Land Consolidation Center Ministry of Natural Resources Key Laboratory of Land Consolidation and Rehabilitation Ministry of Natural Resources Key Laboratory of Digital Mapping and Land Information Application Ministry of Natural Resources Department of Geography & Planning University of Toronto Department of Geography The University of Hong Kong

The subtropical region of China possesses abundant forest resources and features a mountainous *** the implementation of policies such as natural forest protection,the Grain for Green Project,and other initiatives since the beginning of the 21st century,coupled with climate change,the forest resources in this region have undergone significant changes compared to historical *** addition,forest resources distributing mainly in mountainous areas also implies that these changes may vary significantly with *** explore the spatiotemporal dynamics of forest distribution in subtropical China since 2000,especially the trend of changes with elevation,we analyzed the data from two land cover products focusing on forest cover and forest *** used a hierarchical approach,in which coarse-classification forest cover data with relatively small uncertainties impose constraints on forest type data with larger uncertainties,to achieve a reasonable balance between obtaining more details and reducing data *** first divided the forest cover data into‘unchanged'and‘changed'*** the constraints by the forest cover results,we further analyzed the‘unchanged'and‘changed'forest *** results indicated that,since the implementation of ecological engineering and management policies,54%of the area in the subtropical region had maintained unchanged forest cover attributes over the past 20 years,which implied the good state of ecological *** results also showed that dynamic conversions existed in the long term between forests and lands for essential production needs like *** elevational variations of forest cover suggested that the dominant changes came from the conversion between forests and croplands in low-elevation regions below 700 m,the conversion between forests and shrublands in mid-elevation regions of 700–1500 m,and the conversion between forests and grasslands in high-elevation regions above 2000 *** the regio

关键词： Subtropical China Land cover Forest cover Forest type Elevational distribution

Flexible Strain Sensor Based on 3D Electrospun Carbonized Sponge

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Computers, Materials & Continua 2022年第12期73卷 4971-4980页

作者： He Gong Zilian Wang zhiqiang cheng Lin Chen Haohong Pan Daming Zhang Tianli Hu Thobela Louis Tyasi College of Information Technology Jilin Agricultural UniversityChangchun130118China State Key Laboratory of Integrated Optoelectronics College of Electronic Science and EngineeringJilin UniversityChangchun130012China Jilin Province Intelligent Environmental Engineering Research Center Changchun130118China College of Resources and Environment Jilin Agricultural UniversityChangchun130000China Department of Agricultural Economics and Animal Production University of Limpopo0727PolokwaneSouth Africa

Flexible strain sensor has attracted much attention because of its potential application in human motion *** this work,the prepared strain sensor was obtained by encapsulating electrospun carbonized sponge(CS)with room temperature vulcanized silicone rubber(RTVS).In this paper,the formation mechanism of conductive sponge was *** on the combination of carbonized sponge and RTVS,the strain sensing mechanism and piezoresistive properties are *** research and testing,the CS/RTVS flexible strain sensor has excellent fast response speed and stability,and the maximum strain coefficient of the sensor is *** this study,the self-developed CS/RTVS sensor was used to monitor the movements of the wrist joint,arm elbow joint and fingers in real *** experiments show that CS/RTVS flexible strain sensor has good application prospects in the field of human motion monitoring.

关键词： Flexible strain sensor electrostatic spinning technology human motion detection carbonized sponge

A Method Combining Numerical Analysis and Limit Equilibrium Theory to Determine Potential Slip Surfaces in Soil Slopes

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Journal of Mountain Science 2011年第5期8卷 718-727页

作者： XIAO Shiguo YAN Liping cheng zhiqiang Department of Geological Engineering Southwest Jiaotong University Chengdu 610031 China Los Angeles Department of Water and Power Los Angeles USA Department of Applied Mechanics and Engineering Southwest Jiaotong University Chengdu 610031 China

This paper describes a precise method combining numerical analysis and limit equilibrium theory to determine potential slip surfaces in soil slopes. In this method, the direction of the critical slip surface at any point in a slope is determined using the Coulomb’s strength principle and the extremum principle based on the ratio of the shear strength to the shear stress at that point. The ratio, which is considered as an analysis index, can be computed once the stress field of the soil slope is obtained. The critical slip direction at any point in the slope must be the tangential direction of a potential slip surface passing through the point. Therefore, starting from a point on the top of the slope surface or on the horizontal segment outside the slope toe, the increment with a small distance into the slope is used to choose another point and the corresponding slip direction at the point is computed. Connecting all the points used in the computation forms a potential slip surface exiting at the starting point. Then the factor of safety for any potential slip surface can be computed using limit equilibrium method like Spencer method. After factors of safety for all the potential slip surfaces are obtained, the minimum one is the factor of safety for the slope and the corresponding potential slip surface is the critical slip surface of the slope. The proposed method does not need to pre-assume the shape of potential slip surfaces. Thus it is suitable for any shape of slip surfaces. Moreover the method is very simple to be applied. Examples are presented in this paper to illustrate the feasibility of the proposed method programmed in ANSYS software by macro commands.

关键词： Soil slope Stress field Potential slip surface Slope stability Factor of safety Numerical analysis Limit equilibrium method ANSYS software

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资源边际效益与种植业结构调整目标规划

农业工程学报 2005年第12期21卷 16-19页

作者：程智强邱化蛟程序上海市农业科学院科技信息研究所上海201106 中国农业大学可持续农业中心北京100094

根据北京市统计资料和已有研究数据,运用数学规划模型,对北京市种植业结构调整的目标与资源的边际效益间的关系作了分析,把模型的最优解建立在较为合理的资源边际效益和目标边际成本的基础上。结果表明:要提高水的效益和种植业产值,必... 详细信息

根据北京市统计资料和已有研究数据,运用数学规划模型,对北京市种植业结构调整的目标与资源的边际效益间的关系作了分析,把模型的最优解建立在较为合理的资源边际效益和目标边际成本的基础上。结果表明:要提高水的效益和种植业产值,必须控制粮食作物和饲料作物的种植面积,在可灌溉耕地上的露地作物均应实行喷灌,应大力发展设施农业并实行微灌。

关键词：种植业目标规划边际效益边际成本北京

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湘中海相浅层湘冷1井酸压工艺研究及应用

油气井测试 2006年第6期15卷 60-63页

作者：程志强中国地质大学

湘冷1井具有气层埋藏浅(400 m-500 m)、纵向上裂隙发育的特点,属低孔、低渗的含泥质灰岩致密储层。大量室内实验和研究采用“前置液酸压+闭合酸化”工艺技术,并优选了相应降阻酸和闭合酸配方。通过酸压实现了该井工业油气流的突破,取得... 详细信息

湘冷1井具有气层埋藏浅(400 m-500 m)、纵向上裂隙发育的特点,属低孔、低渗的含泥质灰岩致密储层。大量室内实验和研究采用“前置液酸压+闭合酸化”工艺技术,并优选了相应降阻酸和闭合酸配方。通过酸压实现了该井工业油气流的突破,取得了明显的增产效果,为新区海相浅层气的开发探索出了一套成熟的改造增产措施。

关键词：碳酸岩储层浅层天然气前置液酸压闭合酸化

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矿料表面能参数对沥青混合料劈裂强度的影响

建筑材料学报 2016年第4期19卷 779-784,790页

作者：成志强孔繁盛山西省交通科学研究院公路与交通工程研究所山西太原030006 山西省交通科学研究院黄土地区公路建设与养护技术交通行业重点实验室山西太原030006

为研究矿料表面能参数对沥青混合料劈裂强度的影响,首先基于表面能理论对沥青-矿料黏附原理进行阐释;然后测定不同岩性矿料(石灰岩、玄武岩、花岗岩、安山岩和片麻岩)与已知表面能参数滴定液体的接触角,由接触角求得不同矿料的表面能、... 详细信息

为研究矿料表面能参数对沥青混合料劈裂强度的影响,首先基于表面能理论对沥青-矿料黏附原理进行阐释;然后测定不同岩性矿料(石灰岩、玄武岩、花岗岩、安山岩和片麻岩)与已知表面能参数滴定液体的接触角,由接触角求得不同矿料的表面能、极性分量和色散分量,分析矿料各参数与沥青混合料劈裂强度的关系.结果表明:表面能理论可较好解释沥青混合料劈裂强度的形成;不同岩性矿料的沥青混合料劈裂强度与矿料表面能、色散分量呈正相关关系,与矿料极性分量呈负相关关系;矿料表面能参数与其化学组成存在一定关系.

关键词：道路工程沥青混合料试验研究矿料表面能劈裂强度