To evaluate wheel defect, it is necessary to develop a new NDT on railway wheel. Unlikely a conventional NDT system, the NDT system of the present paper can detect a sub-surface crack. In the present paper, the new NDT method is applied to the detection of surface and sub-surface crack defects for railway wheels. To detect the defects for railway wheels, the sensor for new NDT is optimized and the tests are carried out with respect to sub-surface defects respectively. The result shows that the surface crack as well as sub-surface crack could be detected by using new NDT method.

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and * indicate statistical significance at the 1%, 5%, and 10% levels, respectively. Results remain significant when using robust standard errors.

Research Summary Institutional changes create entrepreneurial opportunities and entrepreneurs strategically respond to institutional pressure. However, we lack an understanding of how institutional changes impact entrepreneurial strategies. By exploiting the regional disparities in China's economic transition, we examine how institutional changes alter the effects of entrepreneurial strategies. Using data from an alumni survey in China, we find that relationship‐based strategies are positively associated with firm size in the early stage of the institutional change, innovation‐based strategies appear more effective in the late stage, and “cocoon‐based” strategies are associated with larger firm size in the intermediate stage. We propose that entrepreneurs may temporarily leverage “cocoon institutions” to buffer uncertainty in the broader institutional environment. Overall, we contribute to research at the intersection of institutional change and entrepreneurial strategies. Managerial Summary Institutional environments influence the effectiveness of entrepreneurial strategies. How should entrepreneurs adopt different strategies at different stages of an institutional change? We tackle this question by examining China's transition from a planned economy to a market economy. Using data from an alumni survey in China, we find that relationship‐based strategies promote firm growth in the early stage, innovation‐based strategies appear more effective in the late stage, and locating in science parks benefits firm growth in the intermediate stage. Overall, our study implies that entrepreneurs should adopt different strategies to fit different types of institutional environments. Also, our study provides implications to policymakers that cocoon institutions, such as science parks, may be temporarily effective during the intermediate stage of an institutional change.

The effects of quantum fluctuations due to frustration between nearest neighbors and next-nearest neighbors of the quantum spin-half Heisenberg antiferromagnet on a square lattice are investigated by using the modified spin-wave theory (MSW). We have extended Takahashi's MSW theory, and studied the ground-state and finite-temperature properties of this model. The results calculated within this formalism on the thermodynamics agree quite well with the quantum Monte Carlo estimates, and exact diagonalization results. We have also compared the present method with the conventional spin wave theory.