symmetries in the finite-difference grid. For example, the fault-parallel components of the velocity as well as the normal and an shear stresses are antisymmetric, whereas the fault-perpendicular component of the velocity and the uyx and a , stresses are symmetric across a vertical fault in the xz plane. By careful examination of the numerical implementation, it can be shown that, if the numerical values of the velocity and stress have the aforementioned symmetries about the fault plane at the Nth time step, then they do at upgraded (N + 1)th time step as well. Details of the numerical application of the boundary conditions are described in (76). 10. J. Virieux and R. Madariaga, Bull. Seismol. Soc. Am. 72, 345 (1 98'2). 11. Slip-weakening friction laws similar to Eq. 2 have been extensively studied by rock mechanicists in Japan; see, foiexample, M. Ohnaka, Y. Kuwahara, and K. Yamamoto [Tectonophysics 144, 109 (1987)], M. Ohnaka [Proc. Natl. Acad. Sci. U.S.A. 93, 3795 (1996)], and M. Matsu'ura, H. Kataoka, and B. Shibazaki [Tectonophysics. 21 1, 135 (1 992)J. 12. Actually, the only physical requirement is that friction dissipates energy, such that T integrated over the fault will be less than zero. To our knowledge, the consequences of this less strict requirement have not been reported in the literature. 13. The study of slip weakening and the conditions for spontaneous rupture were introduced in seismology by Y. Ida [J. Geophys. Res. 77, 3796 (1972)], although the conditions had been used in dynamic fracture mechanics [B. Kostrov, L. V. Nikitin, L. M. Flintman, Mech. Solids 4, 112 (1969)l. The friction law used in our simulation is described by A. Palmer and J. Rice [Proc. R. Soc. London Ser. A Recent studies have shown that certain tute for Chemical Biology, The Scripps ~esearch Instielectrochemical etches of single-crystal ptute,
An enzyme switch, or microelectrochemical enzyme transistor, responsive to hydrogen peroxide was made by connecting two carbon band electrodes (∼10 μm wide, 4.5 mm long separated by a 20-μm gap) with an anodically grown film of poly(aniline). Horseradish peroxidase (EC 1.11.1.7) was either adsorbed onto the poly(aniline) film or immobilized in an insulating poly(1,2-diaminobenzene) polymer grown electrochemically on top of the poly(aniline) film to complete the device. In the completed device, the conductivity of the poly(aniline) film changes from conducting (between - 0.05 and + 0.3 V vs SCE at pH 5) to insulating (>+0.3 V vs SCE at pH 5) on addition of hydrogen peroxide. The change in conductivity is brought about by oxidation of the poly(aniline) film by direct electrochemical communication between the enzyme and the conducting polymer. This was confirmed by measuring the potential of the poly(aniline) film during switching of the conductivity in the presence of hydrogen peroxide. The devices can be reused by rereducing the poly(aniline) electrochemically to a potential below +0.3 V vs SCE. A blind test showed that the device can be used to determine unknown concentrations of H(2)O(2) in solution and that, when used with hydrogen peroxide concentrations below 0.5 mmol dm(-)(3), the same device maybe reused several times. The possible development of devices of this type for use in applications requiring the measurement of low levels of hydrogen peroxide or horseradish peroxidase is discussed.
The intelligent diagnosis of wheel flat based on vibration image classification is a promising research subject for performance maintenance of railway vehicles. However, the image representation method of vibration signal and classification network construction under small samples have become two obstacles to intelligent diagnosis of wheel flat. This paper presents a novel frequency-domain Gramian angular field (FDGAF) algorithm to encode the vibration signal of wheel flat to featured images. Furthermore, a modified transfer learning network is introduced to classify these featured images under small samples without any involvement of prior knowledge. The proposed FDGAF can calculate the Gramian angular matrix of axle box acceleration signal in frequency domain and assign frequency position dependence to the featured images to preserve original characteristic information. Then, these featured images can be intelligent classified by a transfer learning network under the condition of 30 sample without require of prior knowledge. To verify the efficiency of this proposed method, 12 cases of artificial wheel flats are processed on a scaled railway test rig, and their axle box acceleration signals are collected to obtain visual diagnosis results. The verfication proves that FDGAF is able to obtain accurate diagnostic results with high separability, for separability indexes of FDGAF reaches 10.8, 8.7, 14.9, and 5.8. We anticipate that this method will find use in the performance maintenance of railway vehicles and the improvement of industrial condition monitoring. INDEX TERMS Intelligent transportation system, fault diagnosis, railway safety, wheels, frequency domain analysis, knowledge transfer.
HALC is a safe, minimally invasive and effective surgical alternative for treating STC, which is comparable to OC.
Reliability assessment of the braking system in a high-speed train under small sample size and zero-failure data is very important for safe operation. Traditional reliability assessment methods are only performed well under conditions of large sample size and complete failure data, which lead to large deviation under conditions of small sample size and zero-failure data. To improve this problem, a new Bayesian method is proposed. Based on the characteristics of the solenoid valve in the braking system of a high-speed train, the modified Weibull distribution is selected to describe the failure rate over the entire lifetime. Based on the assumption of a binomial distribution for the failure probability at censored time, a concave method is employed to obtain the relationships between accumulation failure probabilities. A numerical simulation is performed to compare the results of the proposed method with those obtained from maximum likelihood estimation, and to illustrate that the proposed Bayesian model exhibits a better accuracy for the expectation value when the sample size is less than 12. Finally, the robustness of the model is demonstrated by obtaining the reliability indicators for a numerical case involving the solenoid valve of the braking system, which shows that the change in the reliability and failure rate among the different hyperparameters is small. The method is provided to avoid misleading of subjective information and improve accuracy of reliability assessment under conditions of small sample size and zero-failure data.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.