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A rapid calculation method for predicting roll deformation of six-high rolling mill

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Journal of Iron and Steel Research International 2018年第9期25卷 901-909页

作者： Li Xie An-rui He chao liu National Engineering Research Center for Advanced Rolling Technology University of Science and Technology BeijingBeijing 100083 China

The method to predict roll deformation precisely and efficiently is vital for the strip shape control of a six-high rolling mill. Traditional calculation methods of roll deformation, such as the finite element method and the influence function method, have been widely used due to their accuracies. However, the required calculation time is too long to be applied to the realtime control. Therefore, a rapid calculation method for predicting roll deformation of a six-high rolling mill was proposed, which employed the finite difference method to calculate the roll deflection and used a polynomial to describe the nonlinear relationship between roll flattening and roll contact pressure. Furthermore, a new correction strategy was proposed in the iteration, where the roll center flattening and the roll flattening deviation were put forward and corrected simultaneously in the iteration process according to the static equilibrium of roll. Finally, by the comparison with traditional methods, the proposed method was proved to be more efficient and it was suitable for the online calculation of the strip shape control.

关键词： Six-high rolling mill Roll deformation Influence function method Rapid calculation method Online model

A SINGULAR BIOECONOMIC MODEL WITH DIFFUSION AND TIME DELAY

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Journal of Systems Science & Complexity 2011年第2期24卷 277-290页

作者： Qingling ZHANG Xue ZHANG chao liu Institute of Systems Science Key Laboratory of Integrated Automation of Process Industry Ministry of Edu-cation Northeastern University Shenyang 110004 China. Department of Information and Computational Science Northeastern University at Qinhuangdao Qinhuangdao066004 China.

This paper studies a prey-predator singular bioeconomic system with time delay and diffusion, which is described by differential-algebraic equations. For this system without diffusion, there exist three bifurcation phenomena： Transcritical bifurcation, singularity induced bifurcation, and Hopf bifurcation. Compared with other biological systems described by differential equations, singularity induced bifurcation only occurs in singular system and usually links with the expansion of population. When the diffusion is present, it is shown that the positive equilibrium point loses its stability at some critical values of diffusion rate and periodic oscillations occur due to the increase of time delay. Furthermore, numerical simulations illustrate the effectiveness of results and the related biological implications are discussed.

关键词： Diffusion hopf bifurcation singular bioeconomic model singularity induced bifurcation time delay transcritical bifurcation.

Biped 4R2C Six-bar Mechanism with Inner and Outer Feet

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Chinese Journal of Mechanical Engineering 2016年第1期29卷 45-55页

作者： liu chao WANG Hao YAO Yan-an State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University Shanghai Key Laboratory of Digital Manufacture for Thin-Walled Structures Shanghai Jiao Tong University School of Mechanical Electronic and Control EngineeringBeijing Jiaotong University

Most current biped robots are equipped with two feet arranged in the right and left which inspired by the human body system. Different from the existing configurations, a novel biped robot with inner and outer feet based on a spatial six-bar 4R2C（R and C denote revolute and cylindric joints, respectively） mechanism is proposed. It can move along a line or a curve by three walking modes that are dwell adjustment mode, limit position adjustment mode and any position adjustment mode. Kinematic, gait planning and stability analyses are performed respectively, and a prototype is developed. Lastly, a potential application is considered and two manipulating modes（sphere and cylinder manipulating modes） are carried out. This interesting mechanism feathering its single dosed-chain structure and unique work performance is expected to motivate the configuration creation of biped robots.

关键词： spatial six-bar mechanism 4R2C mechanism biped mechanism

Simple analytical model for depth-averaged velocity in meandering compound channels

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Applied Mathematics and Mechanics(English Edition) 2015年第6期36卷 707-718页

作者： Yuqi SHAN chao liu Maokang LUO College of Mathematics Sichuan University State Key Laboratory of Hydraulics and Mountain River Engineering Sichuan University College of Water Resource and Hydropower Sichuan University

A simple but applicable analytical model is presented to predict the lat- eral distribution of the depth-averaged velocity in meandering compound channels. The governing equation with curvilinear coordinates is derived from the momentum equation and the flow continuity equation under the condition of quasi-uniform flow. A series of experiments are conducted in a large-scale meandering compound channel. Based on the experimental data, a magnitude analysis is carried out for the governing equation, and two lower-order shear stress terms are ignored. Four groups of experimental data from different sources are used to verify the predictive capability of this model, and good predictions are obtained. Finally, the determination of the velocity parameter and the limitation of this model are discussed.

关键词： meandering compound channel simple analytical model lateral distribu-tion method physical experiment depth-averaged velocity

Software testing evolution process model and growth of software testing quality

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Science China(Information Sciences) 2015年第3期58卷 196-201页

作者： HE ZhiTao liu chao YAN HaiHua School of Computer Science and Engineering Beihang University

The paper is based on the research on a formal definition of software testing,with reference to organisms evolution’s heredity/variation and adaptive dynamics *** formal descriptions on the heredity/variation in test versions and the driving force of software testing evolution were established and then a Software Testing Evolution Process Model(STEPM)was *** on the model,the key factors of software testing quality were identified and a Software Testing Quality Framework(STQF)was purposed.A series of formal models obtained in the paper open up new research field in software engineering with wide development foreground and are expected to promote studies on the dependability of software testing,provide ways to evaluate software testing quality and establish formal basis for fully automated testing conducted by programs.

关键词： software testing software testing quality the dependability of software testing the formal definition of software testing software testing evolution process model software testing quality framework

Assessing the quality of metamodels

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Frontiers of Computer Science 2013年第4期7卷 558-570页

作者： Zhiyi MA Xiao HE chao liu Software Institute School of Electronics Engineering and Computer Science Peking University Beijing 100871 China Ministry of Education Key Laboratory of High Confidence Software Technologies (Peking University) Beijing 100871 China School of Computer and Communication Engineering University of Science and Technology Beijing Beiiing 100083 China School of Economics Shandong University of Finance and Economics Jinan 250202 China

The complexity and diversity of modern software demands a variety of metamodel-based modeling languages for software development. Existing languages change continuously, and new ones are constantly emerging. In this situation, and especially for metamodel-based modeling languages, a quality assurance mechanism for metamodels is needed. This paper presents an approach to assessing the quality of metamodels. A quality model, which systematically characterizes and classifies quality attributes, and an operable measuring mechanism for effectively assessing the quality of metamodels based on the quality model, are pre- sented, using UML as the main example.

关键词： quality assessment metamodels metric

Experimental study on inlet vortex in pump sump

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排灌机械工程学报 2019年第9期37卷 769-775页

作者： SONG Xijie liu chao School of Hydraulic Energy and Power Engineering Yangzhou University

In order to study the mechanism of the vortex generation at the bottom of the pump sump below the flare tube,twenty pressure pulsation monitoring points were arranged at the bottom of the pump sump below the flare tube,and the pressure fluctuation experiments were carried out under different flow *** experimental results show that the frequency of pressure fluctuation at the bottom of the pump sump is twice of the rotational frequency of the impeller *** vortex below the flare tube is easy to generate under the large flow conditions and mainly concentrates at the right front position below the flare *** position of the vortex occurring is corresponding to the position of the low-pressure region below flare tube.

关键词： axial-flow pump pump sump vortex pressure fluctuation model experiment

Formation of regulated and unregulated disinfection byproducts during chlorination and chloramination: Roles of dissolved organic matter type, bromide, and iodide

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Journal of Environmental Sciences 2022年第7期34卷 151-160页

作者： Yunsi liu Keqiang liu Michael J.Plewa Tanju Karanfil chao liu Key Laboratory of Drinking Water Science and Technology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China University of Chinese Academy of Sciences Beijing 100049China Water Conservancy Development Research Center Taihu Basin AuthorityMinistry of Water ResourcesShanghai 200433China Department of Crop Sciences and the Safe Global Water InstituteUniversity of Illinois at Urbana-ChampaignUrbanaIL 61801USA Department of Environmental Engineering and Earth Sciences Clemson UniversityAndersonSC 29625USA

Algal blooms and wastewater effluents can introduce algal organic matter(AOM) and effluent organic matter(Ef OM) into surface waters, respectively. In this study, the impact of bromide and iodide on the formation of halogenated disinfection byproducts(DBPs) during chlorination and chloramination from various types of dissolved organic matter(DOM, e.g., natural organic matter(NOM), AOM, and Ef OM) were investigated based on the data collected from literature. In general, higher formation of trihalomethanes(THMs) and haloacetic acids(HAAs) was observed in NOM than AOM and Ef OM, indicating high reactivities of phenolic moieties with both chlorine and monochloramine. The formation of haloacetaldehydes(HALs), haloacetonitriles(HANs) and haloacetamides(HAMs) was much lower than THMs and HAAs. Increasing initial bromide concentrations increased the formation of THMs, HAAs, HANs, and HAMs, but not HALs. Bromine substitution factor(BSF) values of DBPs formed in chlorination decreased as specific ultraviolet absorbance(SUVA) increased. AOM favored the formation of iodinated THMs(I-THMs) during chloramination using preformed chloramines and chlorination-chloramination processes. Increasing prechlorination time can reduce the I-THM concentrations because of the conversion of iodide to iodate, but this increased the formation of chlorinated and brominated DBPs. In an analogous way, iodine substitution factor(ISF) values of I-THMs formed in chloramination decreased as SUVA values of DOM increased. Compared to chlorination, the formation of noniodinated DBPs is low in chloramination.

关键词： Disinfection byproducts Natural organic matter Algal organic matter Effluent organic matter Bromide Iodide Chlorination Chloramination

Ultra-small MoS2 nanodots with rapid body clearance for photothermal cancer therapy

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Nano Research 2016年第10期9卷 3003-3017页

作者： Teng liu Yu chao Min Gao chao Liang Qian Chen Guosheng Song Liang Cheng Zhuang liu Institute of Functional Nano & Soft Materials (FUNSOM) Jiangsu Key Laboratory for Carbon-Based Functional Materials & DevicesSoochow University 199 Ren'ai Road Suzhou 215123 China

The clinical translation of many inorganic nanomaterials is severely hampered by toxicity issues because of the long-term retention of these nanomaterials in the body. In this study, we developed a bio-clearable theranostic agent based on ultra-small MoS2 nanodots, which were synthesized by a facile bottom-up approach through one-step solvothermal decomposition of ammonium tetrathiomolybdate. After modification by glutathione （GSH）, the obtained MoS2-GSH nanodots exhibited sub-10-nm hydrodynamic diameters without aggregation in various physiological buffers. Without showing appreciable in vitro toxicity, such MoS2-GSH nanodots with strong near-infrared （NIR） absorbance could induce remarkable photothermal ablation of cancer cells. Upon intravenous （i.v.） injection, efficient tumor accumulation of MoS2-GSH nanodots was observed by photoacoustic imaging, and further confirmed by analysis of the biodistribution of Mo. Notabl）4 the MoS2-GSH nanodots, in contrast to conventional MoS2 nanoflakes with larger sizes, showed rather efficient body clearance via urine, where the majority of the injected dose was cleared within just seven days. Photothermal ablation of tumors on mice was then realized with the MoS2-GSH nanodots, achieving excellent therapeutic efficacy. This study presents a new type of ultra-small nanoparticle with efficient tumor homing/treatment abilities, as well as rapid body clearance behavior, making it promising for cancer theranostics without long-term toxiciW concerns.

关键词： ultra-small MoS2 nanodots photoacoustic imaging rapid body clearance photothermal therapy