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Experimental analysis of chaotic property of in-cylinder combustion of SI engine

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Experimental analysis of chaotic property of in-cylinder com...

第37届中国控制会议

作者： huanyu di Tielong Shen Department of Engineering and Applied Sciences Sophia University

In spark-ignition（SI） internal combustion engines, fluctuations of the in-cylinder pressure trace and the combustion phase are usually different from one cycle to another. distinguishing the randomness and the chaos, both of which cause the cycle-to-cycle variation（CCV）, is beneficial to the optimization of engine control strategies. In this paper, the cycle-to-cycle varied CA50 series are analyzed based on the chaos theory, and the Lyapunov exponents of CA50 series are calculated. In contrast, an independent repeated random number series is analyzed by the same method. Comparing the Lyapunove exponents of measured CA50 series, some classic chaos systems, and the independent random number series, it can be found that the evolution of CA50 is affected more by randomness than by chaos.

关键词： Chaos Cycle-to-cycle variation SI engine combustion phase

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低合金超高强度钢的微观组织与强化机理

金属热处理 2015年第1期40卷 7-11页

作者：石伟狄桓宇林晓晖张欣清华大学机械工程系北京100084

使用光学显微镜、SEM、TEM、XRD观察G50钢淬火和低温回火后的微观组织形貌,结合低温回火前后G50钢的屈服强度和冲击韧性等力学性能的变化,分析其强韧化机理。结果表明,淬火态G50钢微观组织主要为细小的板条状马氏体,使用TEM可以观测到... 详细信息

使用光学显微镜、SEM、TEM、XRD观察G50钢淬火和低温回火后的微观组织形貌,结合低温回火前后G50钢的屈服强度和冲击韧性等力学性能的变化,分析其强韧化机理。结果表明,淬火态G50钢微观组织主要为细小的板条状马氏体,使用TEM可以观测到有残留奥氏体薄膜在马氏体板条之间,残留奥氏体量很低。G50钢的超高强度来自马氏体相变和晶粒的细化,低温回火处理后G50钢的微观组织是细小的板条状回火马氏体,在保持强度的同时提高了冲击韧性。

关键词：超高强度钢淬火回火强化机理

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超高强度G50钢构件的淬火过程建模与验证

金属热处理 2016年第1期41卷 199-203页

作者：狄桓宇黄姝珂石伟李敬民清华大学机械工程系北京100084 中国工程物理研究院机械制造工艺研究所四川绵阳621900

试验测量了超高强度钢G50不同组织的热物性参数与力学性能参数,测定了马氏体相变动力学参数和马氏体相变塑性系数,建立了超高强度钢G50淬火的温度-组织-应力耦合材料模型。通过反传热计算确定了浸油淬火过程中试验件的表面换热系数。使... 详细信息

试验测量了超高强度钢G50不同组织的热物性参数与力学性能参数,测定了马氏体相变动力学参数和马氏体相变塑性系数,建立了超高强度钢G50淬火的温度-组织-应力耦合材料模型。通过反传热计算确定了浸油淬火过程中试验件的表面换热系数。使用所建立的材料模型和换热系数,模拟计算了试验件浸油淬火过程中的温度、组织和应力的演化过程,温度计算结果和试验测试结果相吻合。

关键词：淬火超高强度钢反传热计算数值模拟

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自动驾驶横向控制模型及方法研究综述

重庆理工大学学报（自然科学） 2021年第7期35卷 71-81页

作者：狄桓宇张亚辉王博钟国旗周文立广州汽车集团股份有限公司汽车工程研究院广州510000 燕山大学机械工程学院河北秦皇岛066004

回顾了自动驾驶的历史,并对用于智能汽车横向控制的整车横向模型和横向控制理论进行梳理和介绍。应用于控制和仿真建模的车辆模型一般有考虑轮胎受力的非线性动力学模型、针对小转角工况的线性动力学模型以及针对低速工况的运动学模型... 详细信息

回顾了自动驾驶的历史,并对用于智能汽车横向控制的整车横向模型和横向控制理论进行梳理和介绍。应用于控制和仿真建模的车辆模型一般有考虑轮胎受力的非线性动力学模型、针对小转角工况的线性动力学模型以及针对低速工况的运动学模型。应用于横向控制的方法有经典控制、最优控制、鲁棒自适应滑模等智能控制以及基于大数据的驾驶员模型控制方法。针对各类控制模型和控制方法进行了评述,并最终根据现有研究成果和趋势完成预测和总结。

关键词：自动驾驶横向控制车辆模型控制方法

Flexible and stretchable metal oxide gas sensors for healthcare

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Science China(Technological Sciences) 2019年第2期62卷 209-223页

作者： ZHENG XiaoQi CHENG huanyu Department of Engineering Science and Mechanics The Pennsylvania State University University Park School of Physical Science and Technology ShanghaiTech University Materials Research Institute the Pennsylvania State University University Park

Capable of measuring volatile biomarker produced by the metabolism from several secretion pathways, flexible and stretchable metal oxide gas sensors have received increasing attention and their development for healthcare starts to gain *** of semiconducting metal oxide on a soft, thin, flexible substrate is the key to enable the flexible property to the gas sensor and such integration typically involves either a direct growth or post transfer of the metal oxide on or to the flexible substrate. In addition to the planar plastic substrate, textile represents another important class of flexible substrates due to its ease of integration with clothing. Moreover, the integration of metal oxide on a single fiber provides a great versatility for different applications. Though flexible sensors can easily conform to the developable surface(e.g., cylinder or cone) from a bending deformation, the conformal contact between the sensor and the tissue surface that is often non-developable requires the sensor to be capable of stretching. Due to the intrinsically brittle nature of the semiconducting metal oxide, several stretchable structures have been explored. Despite the great strides made to the burgeoning area of flexible and stretchable metal oxide gas sensors,grand challenges still need to be overcome before the technology can be applied for the practical application. The selected challenges discussed in this mini-review also represent a fraction of possibilities and opportunities for the research community in the future.

关键词： metal oxide gas sensor flexible and stretchable properties structural design strategies volatile biomarker

Effects of laser processing parameters on properties of laserinduced graphene by irradiating CO_(2) laser on polyimide

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Science China(Technological Sciences) 2022年第1期65卷 41-52页

作者： LIU Ming WU JiaNan CHENG huanyu School of Mechanical Engineering and Automation Fuzhou University Qishan CampusFuzhou 350116China State Key Laboratory of digital Manufacturing Equipment and Technology School of Mechanical Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China Department of Engineering Science and Mechanics The Pennsylvania State UniversityUniversity Park PA 16802USA Department of Materials Science and Engineering The Pennsylvania State UniversityUniversity Park PA 16802USA

The emerging technique of carbonization of polyimide(PI)by direct laser writing receives great attention for its flexibility,versatility,and ease-of-patterning capability in creating a variety of functional laser-induced graphene(LIG)sensors and *** prepared by CO_(2) laser irradiating of the PI film is characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD),transmission electron microscope(TEM),specific surface area analyzer,synchronous thermal analysis,and Raman spectroscopy with the focus on investigating the effects of laser parameters(e.g.,power,scanning speed)on the microstructure,thickness,and sheet resistance of *** TEM and XRD indicate that LIG is composed of many graphene layers with a layer spacing of 0.34 *** specific surface area of LIG decreases with the increase of laser *** ratio of the thickness of LIG over the depth of the carbonized PI film as the expansion ratio characterizes the expansibility of *** influence of image resolution and off-focus value on the sheet resistance of LIG is explained by the superposition mechanism of laser scanning spots.

关键词： CO_(2)laser laser parameters laser-induced graphene characterization sheet resistance

Inference for dependence competing risks from bivariate exponential model under generalized progressive hybrid censoring with partially observed failure causes

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Journal of Systems Engineering and Electronics 2019年第1期30卷 201-208页

作者： WANG Liang LI huanyu MA Jin'ge School of Mathematics and Statistics Xidian University

Inference are considered for the dependence competing risks model by using the Marshal-Olkin bivariate exponential distribution. Under generalized progressively hybrid censoring with partially observed failure causes, the maximum likelihood estimators are established, and the approximate confidence intervals are also constructed via the observed Fisher information ***, Bayes estimates and highest probability density credible intervals are presented and the importance sampling technique is used to compute corresponding results. Finally, the numerical analysis is proposed for illustration.

关键词： dependence competing risk generalized progressive hybrid censoring bivariate exponential distribution Bayesian inference.

A novel smart steel strand based on optical-electrical co-sensing for full-process and full-scale monitoring of prestressing concrete structures

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International Journal of Smart and Nano Materials 2023年第3期14卷 337-368页

作者： huanyu Yang Zhi Zhou Jinping Ou Faculty of Infrastructure Engineering Dalian University of TechnologyDalianLiaoning 116024China School of Civil and Architectural Engineering Hainan UniversityHaikouHainanChina Harbin Institute of Technology(Shenzhen) School of Civil and Environmental EngineeringShenzhenGuangdongChina

As the main load bearing component,the steel strand has a significant impact on the safety of civil ***-time monitoring of steel strand stress distribution throughout the damage process is an impor-tant aspect of civil infrastructure health ***,this study proposes an optical-electrical co-sensing(OECS)smart steel strand with the DOFS and CCFPI embedded *** can simultaneously measure small strains in the initial damage phase with high accuracy and obtain information in the large deformation phase with relatively low *** experiments were carried out to test its sensing *** shows both DOFS and CCFPI have good linearity,repeatability and *** comparison to DOFS,CCFPI has a relatively lower accuracy and resolution,but a large enough measurement range to tolerate the large strain in the event of a steel strand *** verify the reliability of the proposed smart steel strand in real structures,the strand strain distribution in the full damage process of bonded prestressed beams under four-point bending loading was monitored using the smart steel strand as a prestressing *** strain measured by the OECS steel strand is shown to reflect the deformation and stiffness variation of prestressed beams under different load.

关键词： distributed optical fiber sensor(DOFS) Coaxial cable fabry–perot interferometer(CCFPI) Smart steel strand Prestress monitoring Optical-electrical co-sensing

Highly sensitive piezoresistive pressure sensors based on laser-induced graphene with molybdenum disulfide nanoparticles

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Science China(Technological Sciences) 2021年第11期64卷 2408-2414页

作者： HAO DaPeng YANG RuoXi YI Ning CHENG huanyu School of Science Xi'an Aeronautical UniversityXi'an 710077China Department of Engineering Science and Mechanics The Pennsylvania Stale UniversityUniversity ParkState College PA 16802USA School of Mechanical Engineering Hebei University of Technology'Tianjin 300401China Department of Materials Science and Engineering The Pennsylvania State UniversityUniversity ParkState College PA 16802USA

Wearable pressure sensors have drawn significant attention because of their extensive applications in motion detection, tactile sensing, and health monitoring. However, the complex manufacturing process and high cost of active materials make low-cost,large-scale production elusive. In this work, we report a flexible piezoresistive pressure sensor assembled with two 3D laserinduced graphene(LIG) foam electrodes on a polyimide thin film from a simple laser scribing process in the ambient environment. The design of the air gap between the two foam electrodes allows the sensor to showcase a low limit of detection of 0.274 Pa, which provides favorable sensing performance in motion detection and wrist pulse monitoring. The addition of spherical MoS2 nanoparticles between the two foam electrodes further enhances the sensitivity to 88 k Pa-1 and increases the sensing range to significantly outperform the previous literature reports. The demonstrated LIG pressure sensors also exhibit fast response/recovery rates and excellent durability/repeatability.

关键词： piezoresistive pressure sensor laser-induced graphene foam molybdenum disulfide nanoparticles health monitoring