Using the density functional theory, we have demonstrated the chemical functionalization of semiconducting graphene nanoribbons (GNRs) with Stone-Wales (SW) defects by carboxyl (COOH) groups.It is found that the geometrical structures and electronic properties of the GNRs changed significantly, and the electrical conductivity of the system could be considerably enhanced by mono-adsorption and double-adsorption of COOH, which sensitively depends upon the axial concentration of SW defects COOH pairs (SWDCPs). With the increase of the axial concentration of SWDCPs, the system would transform from semiconducting behavior to p-type metallic behavior. This fact makes GNRs a possible candidate for chemical sensors and nanoelectronic devices based on graphene nanoribbons.

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We present a general theory to explore energy transfer in nonequilibrium spin-boson models within the framework of nonequilibrium Green's function (NEGF). In contrast to conventionally used NEGF methods based on a perturbation expansion in the system-bath coupling, we adopt the polaron transformation to the Hamiltonian and identify the tunneling term as a perturbation with the system-bath coupling being treated nonperturbatively, herein termed the polaron-transformed NEGF method. To evaluate terms in the Dyson series, we further utilize the Majorana-fermion representation. The proposed method not only allows us to deal with weak as well as strong coupling regime, but also enables an investigation on the role of bias. As an application of the method, we study the energy transfer between two Ohmic bosonic baths mediated by a spin. For a unbiased spin system, our energy current result smoothly bridges predictions of two benchmarks, namely, the quantum master equation and the nonequilibrium non-interacting blip approximation, thus our method is beyond existing theories. In case of a biased spin system, we reveal a bias-induced nonmomotonic behavior of the energy conductance in the intermediate coupling regime, due to the resonant character of the energy transfer. This finding may offer a nontrivial quantum control knob over energy transfer at the nanoscale.

This paper uses strains measured by fiber Bragg grating (FBG) sensors to estimate the static or dynamic deflection curve of bending beam structures. The deflection estimation method is only based upon the geometric equations of a beam structure without knowing the material information. At each cross section of a beam structure, two FBG strain sensors are installed, and the curvature at the cross section can be estimated by using the two measured strains from the geometric equation. Then the curvature function is assumed as a polynomial function and the coefficients can be estimated using least squares method. Finally, the deflection curve is estimated by integrating the curvature function twice. For dynamic deflection estimation, since only the geometric equations are used, and at each time step, the geometric equations can be also used for a dynamic system. Therefore, at each time step, the deflection can be estimated using the proposed method and the dynamic deflection can be finally obtained. The method is verified by the simulations of a continuous beam under static loads and experimental tests of a simply supported beam under various static loads. A simply support beam under moving loads is also simulated to verify the method for dynamic deformation estimation. All the numerical and test results show that the method can estimate the static and dynamic deflection curve of beam structures with a high accuracy.

Studying typhoon risk perception and its influencing factors help reveal potential risk factors from the perspective of the public and provide a basis for decision-making for reducing the risk of typhoon disasters. The purpose of this study is to assess the risk perception and related factors of Macao residents in China. Information was collected from 983 participants using a structured questionnaire with an effective utilization rate of 94.2%. Descriptive statistics, univariate analysis and correlation analysis were used to analyze the data. The results show that, on the one hand, there are significant differences in risk perception on the factors included: (1) age, education and other demographic characteristics; (2) health status, occupation, length of stay, residence area, residence floor, family organization structure and individuals monthly income and other personal or family conditions; (3) channels and quantity of typhoon information acquisition; (4) degree of mastery of relevant risk aversion knowledge. On the other hand, some factors still have a moderate or high level of correlation with risk perception: (1) The older the respondent, the lower the education level, the lower the income, the lower the risk perception of property damage, health impact and life threat. (2) The more children or elderly people in the family, the higher the risk perception of respondents. (3) The more risk knowledge, the lower the risk perception. (4) The more channels for obtaining information, the lower the fear level and the overall impact of risk perception. (5) The stronger the risk perception, the more positive disaster response behaviors would be taken by the public. In addition, the more information acquisition channels and the less risk knowledge respondents have, the greater the risk perception of the overall impact and the fear of the typhoon; the fewer information access channels and less risk knowledge respondents have, the greater the risk perceptions of property damage, health effects and life threats.

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The nonlinear spin-dependent transport properties in zigzag molybdenum-disulfide nanoribbons (ZMNRs) with line defects are investigated systematically using nonequilibrium Green’s function method combined with density functional theory. The results show that the line defects can enhance the electronic transfer ability of ZMNRs. The types and locations of the line defects are found critical in determining the spin polarization and the current-voltage (I-V) characteristics of the line defected ZMNRs. For the same defect type, the total currents of the ribbons with the line defects in the centers are lager than those on the edges. And for the same location, the total currents of the systems with the sulfur (S) line defect are larger than the according systems with the molybdenum (Mo) line defect. All the considered systems present magnetism properties. And in the S line defected systems, the spin reversal behaviors can be observed. In both the spin-up and spin-down states of the Mo line defected systems, there are obvious negative differential resistance behaviors. The mechanisms are proposed for these phenomena.

The equilibrium lattice parameters, electronic structure, bulk modulus, Debye temperature, heat capacity and Gibbs energy of TiB and TiB 2 were investigated using the pseudopotential plane-wave method based on density functional theory (DFT) and the improved quasi-harmonic Debye method. The results show that the total density of states (DOS) of TiB 2 is mainly provided by the orbit hybridization of Ti-3d and B-2p states, and the total DOS of TiB is mainly provided by the hybrids bond of Ti-3d and B-2p below the Fermi level and Ti-Ti bond up to the Fermi level. The Ti-B hybrid bond in TiB 2 is stronger than that in TiB. Finally, the enthalpy of formation at 0 K, heat capacity and Gibbs free energy of formation at various temperatures were determined. The calculated results are in excellent agreement with the available experimental data.