Fault Frequency Identification of Rolling Bearing Using Reinforced Ensemble Local Mean Decomposition

The vibration signal of rolling bearing exhibits the characteristics of energy attenuation and complex time-varying modulation caused by the transmission with multiple interfaces and complex paths. In view of this, strong ambient noise easily masks faulty signs of rolling bearings, resulting in inaccurate identification or even totally missing the real fault frequencies. To overcome this problem, we propose a reinforced ensemble local mean decomposition method to capture and screen the essential faulty frequencies of rolling bearing, further boosting fault diagnosis accuracy. Firstly, the vibration signal is decomposed into a series of preliminary features through ensemble local mean decomposition, and then the frequency components above the average level are energy-enhanced. In this way, principal frequency components related to rolling bearing failure can be identified with the fast spectral kurtosis algorithm. Finally, the efficacy of the proposed approach is verified through both a benchmark case and a practical platform. The results show that the selected fault characteristic components are accurate, and the identification and diagnosis of rolling bearing status are improved. Especially for the signals with strong noise, the proposed method still could accurately diagnose fault frequency.

Structural basis of dynamic P5CS filaments

The bifunctional enzyme Δ1-pyrroline-5-carboxylate synthase (P5CS) is central to the synthesis of proline and ornithine. Pathogenic mutations in P5CS gene (ALDH18A1) lead to neurocutaneous syndrome and skin relaxation connective tissue disease in humans, and P5CS deficiency seriously damages the ability to resist adversity in plants, which has an essential role in agriculture and human health. Recently, P5CS has been demonstrated forming the cytoophidium in vivo and filaments in vitro. However, the underlying mechanism for the function of P5CS filamentation and catalyze the synthesis of P5C is hardly accessible without structural basis. Here, we have succeeded in determining the full-length structures of Drosophila P5CS filament in three states at resolution from 3.1 to 4.3 Å under cryo-electron microscopy, we observed the distinct ligand-binding states and conformational changes for GK and GPR domain separately. These structures show the distinctive spiral filament is assembled by P5CS tetramers and stabilized by multiple interfaces. Point mutations that deplete such interactions disturb P5CS filamentation and greatly reduce the activity. Our findings reveal a previously undescribed mechanism that filamentation is crucial for the coordination between GK and GPR domains, and provide insights into structural basis for catalysis function of P5CS filament.

Underground Pipeline Identification into a Non-Destructive Case Study Based on Ground-Penetrating Radar Imaging

Ground-penetrating radar (GPR) has become one of the key technologies in subsurface sensing and, in general, in nondestructive testing (NDT), since it is able to detect both metallic and nonmetallic targets. GPR has proven its ability to work in electromagnetic frequency range for subsoil investigations, and it is a risk-reduction strategy for surveying underground various targets and their identification and detection. This paper presents the results of a case study which exceeds the laboratory level being realized in the field in a real case where the scanning conditions are much more difficult using GPR signals for detecting and assessing underground drainage metallic pipes which cross an area with large buildings parallel to the riverbed. The two urban drainage pipes are detected based on GPR imaging. This provides an approximation of their location and depth which are convenient to find from the reconstructed profiles of both simulated and practical GPR signals. The processing of data recorded with GPR tools requires appropriate software for this type of measurement to detect between different reflections at multiple interfaces located at different depths below the surface. In addition to the radargrams recorded and processed with the software corresponding to a GPR device, the paper contains significant results obtained using techniques and algorithms of the processing and post-processing of the signals (background removal and migration) that gave us the opportunity to estimate the location, depth, and profile of pipes, placed into a concrete duct bank, under a structure with different layers, including pavement, with good accuracy.

Cryo-EM structure of human Wntless in complex with Wnt3a

Wntless (WLS), an evolutionarily conserved multi-pass transmembrane protein, is essential for secretion of Wnt proteins. Wnt-triggered signaling pathways control many crucial life events, whereas aberrant Wnt signaling is tightly associated with many human diseases including cancers. Here, we report the cryo-EM structure of human WLS in complex with Wnt3a, the most widely studied Wnt, at 2.2 Å resolution. The transmembrane domain of WLS bears a GPCR fold, with a conserved core cavity and a lateral opening. Wnt3a interacts with WLS at multiple interfaces, with the lipid moiety on Wnt3a traversing a hydrophobic tunnel of WLS transmembrane domain and inserting into membrane. A β-hairpin of Wnt3a containing the conserved palmitoleoylation site interacts with WLS extensively, which is crucial for WLS-mediated Wnt secretion. The flexibility of the Wnt3a loop/hairpin regions involved in the multiple binding sites indicates induced fit might happen when Wnts are bound to different binding partners. Our findings provide important insights into the molecular mechanism of Wnt palmitoleoylation, secretion and signaling.

Processing focus in native and non-native speakers of English: an eye-tracking study in the visual world paradigm

This “visual-world” eye-tracking study investigated the processing of focus in English sentences with preverbal only by L2 learners whose L1 was either Cantonese or Dutch, compared to native speakers of English. Participants heard only-sentences with prosodic prominence either on the object or on the verb and viewed pictures containing an object-focus alternative and a verb-focus alternative. We found that both L2 groups showed delayed eye movements to the alternative of focus, which was different from the native speakers of English. Moreover, Dutch learners of English were even slower than Cantonese learners of English in directing fixations to the alternative of focus. We interpreted the delayed fixation patterns in both L2 groups as evidence of difficulties in integrating multiple interfaces in real time. Furthermore, the similarity between English and Dutch in the use of prosody to mark focus hindered Dutch learners’ L2 processing of focus, whereas the difference between English and Cantonese in the realization of focus facilitated Cantonese learners’ processing of focus in English.

A RESONANCE-BASED THROUGH-TUBING CEMENT EVALUATION TECHNOLOGY

Through tubing cement evaluation in a multi-string well has been considered as a cost-efficient way for well integrity evaluation without removing the production tubing. Conventional acoustic cement bond logging methods are not able to operate accurately with the multi-string structure due to an extremely low sensitivity and Signal-to-Noise (SNR) ratio. Therefore, it is important to develop novel technology and apparatus that can accurately and efficiently monitor the cement condition in the multi-pipe cased well. Applications would include use in production, injection, and storage well configurations as well as for plug and abandonment planning. To this end, a novel through-tubing cement evaluation technology based on a Selective Non-Harmonic Resonance (SNHR) is proposed. Unlike the traditional acoustic wave propagation method (WPM), the new tool emits continuous energy to excites the SNHR of the multi-string structure, considered to be a multi-degree of freedom Duffing system. This includes coupling of the hydraulic pressure in fluid and elastic stress-strain of solid materials. The continuous sinusoidal excitation from the SNHR tool drives the structure in a long burst mode and measures the resonance power loss due to the energy leaking through the cement layer, to represent the casing-cement bond, as well as cement-formation bond condition. The SNHR tool, therefore, has overcome the main challenge, which is the acoustic energy reflections and dissipation through multiple interfaces for existing WPMs. The SNHR tool was validated theoretically and experimentally. Results showed that the SNHR tool can reach high sensitivity (> 10%) and SNR (>10 dB) for variable combinations of pipe sizes up to 14”. This implies that the SNHR is a promising technique for evaluating cement bond integrity in the annulus of an outer-most pipe string when multiple inner pipes and their associated annuli are liquid-filled. In addition, the SNHR tool does not require direct coupling to the first pipe string through pads or extensions, which reduces the engineering complexity of a field-worthy instrument.