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大众心理学 2024年第3期 37-37,36页

作者：袁彦西北师范大学心理学院

什么是“terribletwo”?带孩子有经验的老人会说:“小孩子长到和桌子一样高的时候,麻烦就开始了。”尽管他可能从来没有听说过“两岁反抗期”之说,但他的说法确实反映了“群众的智慧”。孩子长到和桌子一样高,正是两岁左右。

关键词： two ible 桌子

two meters graphene ?lm for generators

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Science Bulletin 2019年第8期64卷 487-489页

作者： Zhibin Zhang Kaihui Liu State Key Laboratory for Mesoscopic Physics School of Physics Peking University

Physicists and especially applied physicists long for a convenient way for converting mechanical, solar energy, and thermal energy into electricity, which makes up our modern lives—from a small LED light to many integrated communication devices. Since the breakthrough work by Faraday in the beginning of the 19th century, the harvesting of electricity has been the hot topic in our modern society.

关键词： two meters graphene film for generators

Strength and failure characteristics of sandstone containing two circular holes filled with two types of inclusions under uniaxial compression

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Journal of Central South University 2017年第11期24卷 2487-2495页

作者：杜明瑞靖洪文苏海健朱谭谭陈敏亮 State Key Laboratory for Geomehanics&Deep Underground Engineering(China University of Mining and Technology) Xuzhou 221116China

Plate shaped sandstones containing two fabricated circular holes that were filled with gypsum and high-strength concrete respectively were prepared for studying the effects of ligament length L ligament incline angle α, as well as filling modes on their strength properties and failure modes. The results show that the initial cracks can be categorized as wing crack, axial tensile crack and curved tensile crack. The failure modes of ligaments can be categorized as mode of single inclined crack, mode of single axial crack and mode of two parallel cracks. The final failure modes of all specimens can be categorized as the tension-shear mixed failure and shear failure. The strength of inclusions shows little influence on the final failure modes of specimens, while the failure modes vary with L and α. When α is a fixed value, the peak strength σc and elastic modulus Ec of tested specimens increase firstly with increasing L and reaches to the maximum value at L of 16 mm, then declines. When L is a fixed value, σc declines firstly and then turns to increase as α increases to 75° from 45°, while Ec increases linearly. The axial stress σp performs the similar variation trends with those of σc versus increasing L and α when ligaments fail.

关键词： sandstone two circular holes inclusions uniaxial compression failure modes strength properties

The two steps thermal decomposition of titanium hydride and two steps foaming of Al alloy

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Science China Chemistry 2005年第6期48卷 523-529页

作者： SHANG Jintang HE Deping South-east University Nanjing 210096 China South-east University Nanjing 210096 China

two steps foaming (TSF) technique was proposed to prepare shaped Al alloy foam. Based on the thermal decomposition kinetics equation of titanium hydride, the relationship be-tween two steps thermal decomposition kinetics of titanium hydride and two steps foaming Al alloy melt was studied. two steps thermal decomposition curve of titanium hydride under in-creasing and constant temperature was calculated respectively. The hydrogen mass needed in the second foaming step was also calculated. Results showed that the hydrogen mass of the second thermal decomposition of titanium hydride is enough for the second foaming step in the condition of as-received Al melt foaming. Experimental and theoretical results indicate that two steps foaming technique can be used to prepare Al alloy foam with high porosity, shaped com-ponents and sandwich with Al alloy foam core.

关键词： two steps foaming, titanium hydride, thermal decomposition kinetics, Al alloy foam, shaped components.

two species of microcracks

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Applied Geophysics 2014年第1期11卷 1-8,115页

作者： Stuart Crampin 高原 British Geological Survey School of GeoSciences University of Edinburgh Institute of Earthquake Science China Earthquake Administration

We identify two interrelated but independent species of microcracks with differentorigins and different distributions. One species is the classic high-stress microcracksidentified in laboratory stress-cells associated with acoustic emissions as microcracks openwith increasing stress. The other species is the low-stress distributions of closely-spacedstress-aligned fluid-saturated microcracks that observations of shear-wave splitting （SWS）demonstrate pervade almost all in situ rocks in the upper crust, the lower crust, and theuppermost 400 km of the mantle. On some occasions these two sets of microcracks may beinterrelated and similar （hence ＇species＇） but they typically have fundamentally-differentproperties, different distributions, and different implications. The importance for hydrocarbonexploration and recovery is that SWS in hydrocarbon reservoirs monitors crack alignmentsand preferred directions of fluid-flow. The importance for earthquake seismology is that SWSabove small earthquakes monitors the effects of increasing stress on the pervasive low-stressmicrocrack distributions so that stress-accumulation before, possibly distant, earthquakes canbe recognised and impendin~ earthquakes stress-forecast.

关键词： crack-induced anisotropy, fluid-saturate microcracks, shear-wave splitting, stress-forecastin~ earthquakes, two species of microcracks

Control of a two-wheeled Machine with two-directions Handling Mechanism Using PID and PD-FLC Algorithms

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International Journal of Automation and computing 2019年第4期16卷 511-533页

作者： Khaled M. Goher Sulaiman O. Fadlallah School of Engineering University of Lincoln Lincoln LN6 7TS UK Mechanical Engineering Department Auckland University of Technology Auckland 1142 New Zealand

This paper presents a novel five degrees of freedom (DOF) two-wheeled robotic machine (TWRM) that delivers solutions for both industrial and service robotic applications by enlarging the vehicle′s workspace and increasing its flexibility. Designing a two-wheeled robot with five degrees of freedom creates a high challenge for the control, therefore the modelling and design of such robot should be precise with a uniform distribution of mass over the robot and the actuators. By employing the Lagrangian modelling approach, the TWRM′s mathematical model is derived and simulated in Matlab/Simulink?. For stabilizing the system′s highly nonlinear model, two control approaches were developed and implemented: proportional-integral-derivative (PID) and fuzzy logic control (FLC) strategies. Considering multiple scenarios with different initial conditions, the proposed control strategies′ performance has been assessed.

关键词： two-wheeled inverted pendulum (IP) with two direction handling Lagrangian formulation proportional-integral-derivative (PID) fuzzy logic control (FLC) under-actuated systems

Applications of Electrical Capacitance Tomography in two Phase Flow Visualization

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Journal of Thermal Science 2004年第2期13卷 179-186页

作者： Shi Liu Runsheng Yan Haigang Wang Fan Jiang Xiangyun Dong Chinese Acad Sci Inst Engn Thermophys Beijing 100080 Peoples R China

The successful application of Electrical Capacitance Tomography (ECT) depends heavily on the image reconstruction speed and quality. The two requirements usually cannot be satisfied simultaneously. Also, for a large number of acquired 2D ECT images, a 3D presentation of them is much desired to track the variations of the material distribution in a third dimension. To facilitate ECT for practical flow analyses in process engineering, the authors have recently developed algorithms for 3D image presentation and for online iterative image reconstruction that only takes the same time as a linear back projection method but yields good image qualities as the Landweber iterative method does. The new methods have been successfully applied to visualize several classes of two phase flows, namely fluidization, cyclone separation, circulating rate determination in circulating fluidized beds, pneumatic conveying, rotating drum mixing. Special characteristics in each case have been discussed and valuable results are obtained, which are reported in this paper.

关键词： ECT two phase flow visualization.

Numerical Simulation on Flow Past two Side-by-Side Inclined Circular Cylinders at Low Reynolds Number

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China Ocean Engineering 2019年第3期33卷 344-355页

作者： LIU Cai GAO Yang-yang QU Xin-chen WANG Bin ZHANG Bao-feng Ocean College Zhejiang University Zhoushan 316021 China Powerchina Huadong Engineering Corporation Limited Hangzhou 311122 China

A series of three-dimensional numerical simulations is carried out to investigate the effect of inclined angle on flow behavior behind two side-by-side inclined cylinders at low Reynolds number Re=100 and small spacing ratio T/D=1.5 (T is the center-to-center distance between two side-by-side cylinders, D is the diameter of cylinder). The instantaneous and time-averaged flow fields, force coefficients and Strouhal numbers are analyzed. Special attention is focused on the axial flow characteristics with variation of the inclined angle. The results show that the inclined angle has a significant effect on the gap flow behaviors behind two inclined cylinders. The vortex shedding behind two cylinders is suppressed with the increase of the inclined angle as well as the flip-flop gap flow. Moreover, the mean drag coefficient, root-mean-square lift coefficient and Strouhal numbers decrease monotonously with the increase of the inclined angle, which follows the independent principle at small inclined angles.

关键词： two side-by-side inclined cylinders inclined angle wake flow pattern low Reynolds number axial flow

Mixed mode oscillations as well as the bifurcation mechanism in a Duffing’s oscillator with two external periodic excitations

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Science China(Technological Sciences) 2019年第10期62卷 1816-1824页

作者： ZHANG XiaoFang ZHENG JianKang WU GuoQing BI QinSheng Faculty of Civil Engineering and Mechanics Jiangsu UniversityZhenjiang212013China School of Mechanical Engineering Nantong Institute of TechnologyNantong226002China

The main purpose of the paper is to present an approach to account for the mechanism of bursting oscillations occurring in the systems with multiple periodic excitations. Since the traditional slow-fast analysis method can be used only for the systems with two scales in time domain, when there exists an order gap between the exciting frequencies and the natural frequency, how to explore the mechanism of the complicated dynamics remains an open problem, especially for the case when two exciting terms exist. To explain our approach, a relative simple Duffing’s oscillator with two external periodic excitations is introduced as an example. For the case when one exciting frequency is integer times of the other exciting frequency, by employing Moivre’s equation, the two exciting terms can be transformed into the functions of one basic periodic exciting term. Regarding the basic periodic exciting term as a slow-varying parameter, the two exciting terms can be changed into the functions of the slow-varying parameter, based on which the whole model can be transformed into a generalized autonomous system with one slow-varying parameter. Equilibrium branches as well as the related bifurcations of the generalized autonomous system can be derived with the variations of the amplitudes of the two excitations, which describes the relationship between the state variables of the generalized autonomous system and the slow-varying parameter. Considering the slow-varying parameter as a generalized state variable, one may obtain the so-called transformed phase portraits, which present the relationship between the state variable and the slowvarying parameter. The bifurcation mechanism of the mixed oscillations can be obtained by overlapping the equilibrium branches and the transformed phase portraits. Upon the approach, different types of bursting oscillations are presented. It is pointed that when the trajectory moves almost strictly along the segments of the stable equilibrium branches to the fold bifurcation points, jumping phenomen

关键词： multiple external periodic excitations two scales in frequency domain bursting oscillations bifurcation mechanism

From golden rice to a STARice, more than just two steps forward in a pathway

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Science China(Life Sciences) 2019年第2期62卷 280-281页

作者： Wei-Cai Chen Shan Lu State Key Laboratory of Pharmaceutical Biotechnology School of Life Sciences Nanjing University

Carotenoids are widely distributed in higher plants, algae and some bacteria and fungi. For human beings, they are essential phytonutrients that serve not only as precursors of vitamin A.

关键词： From golden rice to a STARice more than just two steps forward in a pathway