A nematic topological superconductor has an order parameter symmetry, which spontaneously breaks the crystalline symmetry in its superconducting state. This state can be observed, for example, by thermodynamic or upper critical field experiments in which a magnetic field is rotated with respect to the crystalline axes. The corresponding physical quantity then directly reflects the symmetry of the order parameter. We present a study on the superconducting upper critical field of the Nb-doped topological insulator Nb x Bi 2 Se 3 for various magnetic field orientations parallel and perpendicular to the basal plane of the Bi 2 Se 3 layers. The data were obtained by two complementary experimental techniques, magnetoresistance and DC magnetization, on three different single crystalline samples of the same batch. Both methods and all samples show with perfect agreement that the in-plane upper critical fields clearly demonstrate a two-fold symmetry that breaks the three-fold crystal symmetry. The two-fold symmetry is also found in the absolute value of the magnetization of the initial zero-field-cooled branch of the hysteresis loop and in the value of the thermodynamic contribution above the irreversibility field, but also in the irreversible properties such as the value of the characteristic irreversibility field and in the width of the hysteresis loop. This provides strong experimental evidence that Nb-doped Bi 2 Se 3 is a nematic topological superconductor similar to the Cu-and Sr-doped Bi 2 Se 3 .

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The dynamic response of a beam under a moving load is a superposition of two components, namely, the moving-frequency component corresponding to the moving load and the natural-frequency component of the beam. This study investigates the closed-form solution of the dynamic response of a damaged simply supported beam subjected to a moving load and examines the effects of the loss of local stiffness on these two components. The study provides deep insights into beam damage detection based on moving load-induced response. Consequently, a simple and intuitive method for damage localization is developed. First, the closed-form solution is derived based on the modal perturbation and modal superposition method. The closed-form solution enables the individual examination of damage-induced changes in moving- and natural-frequency components. The results show that the moving-frequency component is preferred in damage localization. Then, multi-scale discrete wavelet transform is employed to separate the moving-frequency component from the total dynamic response and to subsequently locate the damage. Numerical examples with single or multiple damages are utilized to validate the efficacy of the proposed response computation algorithm and to demonstrate the effectiveness of the corresponding damage localization method. The effects of moving velocity and noise level are carefully studied. In particular, the effects of varying moving velocities and moving vehicular dynamics on damage localization are presented in this paper.

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Summary Mode shape identification is a crucial task in the field of bridge health monitoring. This paper proposes a mass‐normalized mode shape identification method for bridge structures on the basis of its essential property of bearing vehicle load. First, the relationship between the bridge frequencies changes due to a parking vehicle, and the amplitudes of the mass‐normalized mode shapes at the parking point is established through theoretical derivation. Subsequently, the algorithm and procedures to extract the mode shapes by using the frequencies measured on a two‐axle vehicle that parks at different locations of the bridge progressively are proposed. Then the determination of the two‐axle parking vehicle parameters and the distinctive features of the proposed method are discussed. Numerical and experimental examples of different bridge types are conducted to investigate the feasibility and effectiveness of the proposed identification method. The results indicate that the proposed method can obtain high spatial resolution mass‐normalized mode shapes accurately with only one sensor on the parking vehicle.

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