检索结果-南通市图书馆

Cylindrical cavity expansion responses in anisotropic unsaturated soils under plane stress condition

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2022年第6期14卷 1989-2002页

作者： haohua chen Xiaolin Weng Lele Hou Dean Sun Department of Geotechnical Engineering Tongji UniversityShanghai200092China Department of Civil and Architectural Engineering and Mechanics University of ArizonaTucsonAZ85721USA School of Highway Chang’an UniversityXi’an710064China Department of Civil Engineering Shanghai UniversityShanghai200444China

In this paper,an anisotropic critical state model for saturated soils was extended to unsaturated conditions by introducing suction into its yield *** this model with soil-water characteristic curves related to porosity ratio was employed to characterize the coupled hydromechanical behavior of unsaturated anisotropic *** on the plane stress condition,the problem of the cylindrical cavity expansion in unsaturated anisotropic soils was transformed into first-order differential equations using the Lagrangian *** equations were solved as an initial value problem using the Runge-Kutta algorithm,which can reflect the soil-water retention behavior during cavity *** analyses were conducted to investigate the influences of overconsolidation ratio(OCR),suction,and degree of saturation on the expansion responses of a cylindrical cavity in unsaturated anisotropic soil under plane stress *** results show that the above factors have obvious influences on the cavity responses,and the plane strain solution tends to overestimate expansion pressure and degree of saturation but underestimates suction around the cavity compared to the proposed plane stress *** theoretical model proposed in this paper provides a reasonable and effective method for simulating pile installation and soil pressure gauge tests near the ground surface of the unsaturated soils.

关键词： Cylindrical cavity Anisotropic unsaturated soil Plane stress Hydromechanical behavior

Geometry, stability and aromaticity of β-diketiminate-coordinated alkaline-earth compounds

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2019年第12期30卷 2249-2253页

作者： Yuanyuan Li haohua chen Lingbo Qu Ruopeng Bai Yu Lan Department of Biological and Chemical Engineering Chongqing University of EducationChongqing 400067China Cooperative Innovation Center of Lipid Resources and Children’s Daily Chemicals Chongqing University of EducationChongqing 400067China School of Chemistry and Chemical Engineering Chongqing UniversityChongqing 401331China College of Chemistry and Molecular Engineering Zhengzhou UniversityZhengzhou 450006China

Alkaline-earth(Ae) metals have attracted a wealth of interdependent research from synthetic *** Ae-catalyzed organometallic reactions,β-diketiminate is a typical ligand used to stabilize Ae catalysts by forming six-membered rings comprising Ae ***,studies focusing on the configuration of β-diketiminate-coordinated Ae compounds observed that the C-C and C-N bonds are homogeneous and ***,energetic studies observed that the formation of the Ae-incorporated sixmembered rings results in enhanced stability of>20 kcal/*** nucleus-independent chemical shifts,anisotropy of the induced current density,and molecular orbital analyses demonstrated the nonaromaticity of the β-diketiminate-coordinated Ae *** improved stability of these compounds can be explained by the delocalization of the π electrons derived from the β-diketiminate moiety.

关键词： β-Diketiminate-coordinated Alkaline-earth compounds Theoretical study Aromaticity Stability

Theoretical insight into phosphoric acid-catalyzed asymmetric conjugate addition of indolizines to a,β-unsaturated ketones

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2018年第8期29卷 1237-1241页

作者： haohua chen Lei Zhu Kangbao Zhong Xiaoyu Yue Ling-Bo Qu Ruopeng Bai Yu Lan School of Chemistry and Chemical Engineering Chongqing University College of Chemistry and Molecular Engineering Zhengzhou University

Phosphoric acid catalysis is a powerful tool for the construction of new CààC bonds because of its unique LUMO-lowering activity. Theoretical calculations were employed to investigate phosphoric acidcatalyzed asymmetric conjugate addition of indolizines to a,b-unsaturated ketones. The calculation results showed that this transformation proceeds via a reaction pathway involving nucleophilic addition,deprotonation–aromatization, and tautomerization. The computational results showed that deprotonation–aromatization is the rate-determining step and the enantioselectivity-determining *** S-configured product was preferentially generated via a pathway starting from the s-cis conjugated ketone, whereas the s-trans isomer led to a side product with the R configuration. Non-covalent interaction analysis showed that the enantioselectivity is mainly caused by bond-rotation strain in the transition states of the deprotonation–aromatization step.

关键词： Phosphoric acid catalysis Theoretical calculations Mechanism Enantioselectivity

A Design of Remote-Controlled Chalkboard Eraser

在线全文

学校读者我要写书评

暂无评论

Natural Science 2020年第11期12卷 688-698页

作者： haohua chen Qidong Zhou Cambridge A-Level Center Hangzhou Foreign Languages School Hangzhou China

Chalkboard erasers that are commonly used in many schools and education organizations have the poor ability in removing the dust off the chalkboard and collect them. The dust that is not collected will be taken into human bodies via inhalation, which will lead to respiratory diseases. Therefore, it is crucial to design a chalkboard eraser that can collect the dust effectively. If the eraser can be controlled both remotely and manually by people, it can further reduce the amount of dust taken in by human bodies. To achieve remote control, a micro-controller is needed to transfer the infrared radiation (IR) into signals that can control electric motors to move around on the chalkboard. Furthermore, the microfiber is also used as the cleaning material to improve the performance of dust cleaning and collecting. A vacuum pump is needed to create negative pressure between the eraser and the chalkboard so that the eraser can stick to it. The result shows a stronger ability in removing and collecting dust. With the help of the Arduino UNO board, the remote control is successfully achieved, and the eraser can move on the chalkboard freely according to the order.

关键词： Remote-Control Arduino UNO Board Passive Infrared Radiation Sensor Microfiber Vacuum Pump

Phase diagram and dielectric properties of Pb(In_(1/2)Nb_(1/2))O_(3)-Pb(Mg_(1/3)Nb_(2/3))O_(3)-PbTiO_(3) ceramics

维普期刊数据库评论

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 Advanced Dielectrics 2015年第2期5卷 67-71页

作者： Dabin Lin haohua chen Zhenrong Li Zhuo Xu Electronic Materials Research Laboratory Key Laboratory of Education Ministry/International Center for Dielectric Research Xi'an Jiao Tong University Xi'an 710049P.R.China Laboratory of Thin Film Techniques and Optical Test Xi'an Technological University Xi'an 710032P.R.China

xPb(In_(1/2)Nb_(1/2))O_(3)–yPb(Mg_(1/3)Nb_(2/3))O_(3)–zPbTiO_(3)(xPIN–yPMN–zPT)ternary ceramics with morphotropic phase boundary(MPB)composition were synthesized by columbite precursor ***–yPMN–zPT phase diagram was investigated by x-ray diffraction and dielectric *** to the results of dielectric measurements,the Curie temperatures(Tc)and rhombohedral to tetragonal phase transition temperature(T_(r-t))were found to be in the range of 173–212℃and 114–155℃,respectively,indicating that the _(Tr-t) was increased with adding PIN *** the MPB region,the highest T_(r-t)=155℃was found in 0.32PIN–0.38PMN–0.30PT ceramic,that greatly expanded temperature usage range.

关键词： Relaxor ferroelectric dielectric phase diagram.

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

多年冻土区太阳能制冷桩基主动冷却效果

清华大学学报（自然科学版） 2024年第5期64卷 821-830页

作者：孙兆辉刘建坤陈浩华游田中山大学土木工程学院珠海519082 南方海洋科学与工程广东实验室珠海519082

桩基是多年冻土区最为常见的基础形式之一,降低桩基工程热扰动和提高桩基长期稳定性是冻土工程研究的重点。该文将太阳能制冷技术引入多年冻土区桩基工程,并开展主动冷却桩基现场试验与数值模拟研究。试验结果表明:温控桩壁的制冷温度... 详细信息

桩基是多年冻土区最为常见的基础形式之一,降低桩基工程热扰动和提高桩基长期稳定性是冻土工程研究的重点。该文将太阳能制冷技术引入多年冻土区桩基工程,并开展主动冷却桩基现场试验与数值模拟研究。试验结果表明:温控桩壁的制冷温度可降至负温以下,运行3、 10和30 d的制冷半径分别达到0.65、 1.24和1.5 m以上;通过理论分析与数值反演估算温控桩的有效制冷功率约180 W,制冷因数为0.9。模拟结果表明:制冷时长越大,桩壁温度振幅越大,稳定温度越低;制冷时长6、 9和12 h/d所对应的桩壁温度分别可降至-2.39、-3.48和-4.45℃;10 a后的影响半径分别超出6.68、 8.34和9.46 m;温控桩服役10 a后停止运行,桩周冻土仍可以在2~4 a内处于低温稳定状态。

关键词：多年冻土区太阳能制冷技术桩基础地温制冷效果

在线全文

学校读者我要写书评

暂无评论

复杂扰动下水下机器人的轨迹精确跟踪控制

中国舰船研究 2022年第2期17卷 98-108页

作者：陈浩华赵红王宁郭晨鲁挺王宁大连海事大学船舶电气工程学院辽宁大连116026 哈尔滨工程大学船舶工程学院黑龙江哈尔滨150001

[目的]针对外界复杂干扰下水下机器人三维轨迹精确跟踪控制的问题,提出一种基于有限时间扰动观测器的非奇异终端滑模控制方法。[方法]设计非奇异终端滑模轨迹跟踪控制器,保证跟踪误差在有限时间内精确收敛到零。在外界多维度时变干扰下... 详细信息

[目的]针对外界复杂干扰下水下机器人三维轨迹精确跟踪控制的问题,提出一种基于有限时间扰动观测器的非奇异终端滑模控制方法。[方法]设计非奇异终端滑模轨迹跟踪控制器,保证跟踪误差在有限时间内精确收敛到零。在外界多维度时变干扰下,设计有限时间扰动观测器,提高系统的抗干扰能力。[结果]利用Lyapunov函数证明所设计控制策略可以有限时间稳定。采用MATLAB进行仿真实验,在阶跃扰动下与反步滑模控制方法仿真对比,表明所提方法可实现轨迹的精确跟踪。[结论]研究结果可为水下机器人的三维轨迹精确跟踪提供解决思路。

关键词：水下机器人三维轨迹跟踪有限时间扰动观测器阶跃扰动非奇异终端滑模反步滑模

同方期刊数据库博看期刊

在线全文

学校读者我要写书评

暂无评论

基于混合式教学模式微课程的评价方式研究

吉林省教育学院学报 2018年第12期34卷 136-138页

作者：陈浩华常州轻工职业技术学院江苏常州213164

电子信息技术的发展和计算机技术的革新为各行各业都带来了新的生机。运用构建主义方法,以在线学习或移动学习为目的的微课程应运而生。微课程作为一种新型教育状态,在人们生活中扮演着越来越重要的地位。本文主要讲述混合式教学模式微... 详细信息

电子信息技术的发展和计算机技术的革新为各行各业都带来了新的生机。运用构建主义方法,以在线学习或移动学习为目的的微课程应运而生。微课程作为一种新型教育状态,在人们生活中扮演着越来越重要的地位。本文主要讲述混合式教学模式微课程的教学作用和教学现状,并对混合式教学模式下微课程的评价方式进行探讨,旨在为发展混合式教学模式微课程的发展作出借鉴。

关键词：混合式教学模式微课程评价方式

在线全文

学校读者我要写书评

暂无评论

深基坑工程遇位置不明废弃人防空洞处理措施

工程质量 2020年第8期38卷 91-94页

作者：丁亚雷陈豪华中铁第六勘察设计院集团有限公司天津300000

旧城区地下工程建设过程中常遇废弃地下人防工程,不同工程遇人防工程的处理方式各异,如何合理处理需要工程技术人员根据工程自身特点选择适宜的处理方式。以某管廊工程深基坑为依托,对比研究了几种处理方案,分析可能存在的风险点及重难... 详细信息

旧城区地下工程建设过程中常遇废弃地下人防工程,不同工程遇人防工程的处理方式各异,如何合理处理需要工程技术人员根据工程自身特点选择适宜的处理方式。以某管廊工程深基坑为依托,对比研究了几种处理方案,分析可能存在的风险点及重难点,选择的处理方案在实际实施中取得了很好的效果。在该工程经验的基础上对本问题进行了拓展延伸,对类似工程的设计和施工具有一定的指导意义。

关键词：深基坑人防空洞围护结构施工