The diagnosis of compound-fault is always a difficult point, and there is not an effective method in equipment diagnosis field, then a new method of compound-fault diagnosis was presented. The vibration signals at start-up in the gearbox are non-stationary signals, and traditional ways of diagnosis have low precision. Order tracking and wavelet packet and rough sets theory are introduced in the compound-fault diagnosis of bearing. First, the vibration signals at start-up were resampled using computer order tracking arithmetic and equal angle distributed vibration signals were obtained, and wavelet packet has been used for equal angle distributed vibration signals decomposition and reconstruction. Then, energy distribution of every frequency band can be calculated according to normalization process. A new feature vector can be obtained, then clear and concise decision rules can be obtained by rough sets theory. Finally, the result of compound-fault example proves that the proposed method has high validity and more amplitude appliance foreground.
Single‐crystal elasticity of both α‐ and β‐orthopyroxene was determined up to 20 GPa and 300 K by Brillouin scattering. Using the derived full elastic moduli (Cij), we investigated the contribution of the metastable pyroxene to the seismically observed 3%–5% low‐velocity anomalies along the subducting slab in the top transition zone. Our modeled results show that a harzburgite wedge with a 1000‐K colder geotherm and metastable α‐orthopyroxene and olivine displays compressional (VP) and shear‐wave (VS) velocities 3.0%–3.6(6)% and 2.0%–2.8(6)% lower than the surrounding mantle at 410–460 km depth, respectively. At deeper depth up to 520 km, VP and VS of this metastable wedge with β‐orthopyroxene and olivine are 3.6%–4.4(6)% and 2.8%–4.3(6)% lower than the pyrolitic mantle, respectively. The presence of both metastable orthopyroxene and olivine instead of metastable olivine alone helps better explain the origin of the low‐velocity anomalies within the subduction slab in the top transition zone.
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