Recent Progress on Mechanical Condition Monitoring and Fault Diagnosis

AbstractMechanical equipments are widely used in various industrial applications. Generally working in severe conditions, mechanical equipments are subjected to progressive deterioration of their state. The mechanical failures account for more than 60% of breakdowns of the system. Therefore, the identification of impending mechanical fault is crucial to prevent the system from malfunction. This paper discusses the most recent progress in the mechanical condition monitoring and fault diagnosis. Excellent work is introduced from the aspects of the fault mechanism research, signal processing and feature extraction, fault reasoning research and equipment development. An overview of some of the existing methods for signal processing and feature extraction is presented. The advantages and disadvantages of these techniques are discussed. The review result suggests that the intelligent information fusion based mechanical fault diagnosis expert system with self-learning and self-updating abilities is the future research trend for the condition monitoring fault diagnosis of mechanical equipments

Design of an Aircraft Rolling Bearings Platform and its Thermal Performance Evaluation

The thermal instability is one crucial factor leading to low bearing operation performance. This paper presents a novel experiment device for thermal performance investigation of an aircraft rolling bearings. A bidirectional fixing structure was designed to balance the spindle thermal deformation. The hydraulic loading was used and the oil injection manner was adopted in the new device. Experimental test was conducted using the new device and experimental results were compared with the calculation based on the temperature and thermal nodes theory. The comparison demonstrates that the temperature distribution trends between the theoretical and experimental results remained the same; specifically, the error between the theoretical and experimental results was 1.0 % under the condition of 200 kg load and 2250 rpm driving speed. Consequently, the analysis result shows that the new device is feasible and reliable to provide precise thermal characteristics for the aircraft rolling bearings

A Comprehensive Optimum Design Method of Monitorability-based Design for Mechanical System Using Collaborative Theory

Abstract: The study aims to investigate the mechanical system optimum design based on collaborative theory. Due to the complexity of the modern machinery, mechanical systems are readily to damage when unexpected failures occur on important components. It is therefore, critical to monitor the machine state for preventing the impending faults. The key issues to realize the feasible and reliable mechanical condition monitoring is information acquisition, which relies on the available design of the detection devices. Literature review indicates that an extensive attention has been put on the so called Monitorability in the systematic design of mechanical systems. Monitorability is emphasized that in the original design of mechanical systems one should consider available information acquisition property. Moreover, monitorability-based design is known as a design attribute of mechanical system worldwide. However, less work has been done in this field. In this study, a novel method based on collaborative theory is proposed for the monitorability design. The connotation and application of collaborative theory for monitorability design are discussed in details. The information synergy model and organization framework of monitorability-based design are established by using computer technology and network technology. The experiments demonstrate the effectiveness of the proposed monitorability design system for a more powerful optimum design of mechanical systems and show a promising future for the industrial applications

Analysis of occupational identity among family doctor teams and its influencing factors in Chengdu

BackgroundThe contracted family doctor services are the embodiment of the implementation of the new medical reform policy, and the transformation of the grass-roots health service mode. Studies have proved that the occupational stress in medical staff was at a high level. The enhancement of professional identity will contribute to strengthen team building，alleviate job burnout, and reduce turnover intention of family doctors. ObjectiveTo investigate the current situation of occupational identity among family doctor teams in Chengdu, to examine potential influencing factors of occupational identity, and to provide a reference for promoting career development and team building of family doctor teams. MethodsMulti-stage random cluster sampling was adopted to enroll study participants form 46 primary healthcare centers where family doctor contract services were implemented among 23 districts and counties in Chengdu between March 4 and 26, 2021. A total of 2 681 family doctors participated in this survey. A self-reported survey was conducted to collect participants' demographic and occupational data. The Effort-Reward Imbalance (ERI）questionnaire was implemented to assess occupational stress. The Professional Identity Scale was used to appraise occupational identity. ResultsA total of 2 327 valid questionnaires were collected, with a valid recovery rate of 86.80%, involving 1 715 females (73.7%) and 612 males (26.3%), with dominant age groups of 26−35 years (43.3%) and 36−45 years (30.4%), a high proportion of being married (82.8%), having college (36.0%) and undergraduate (47.3%) education, a high proportion of primary titles (66.0%) and informal work contract (66.1%). About 88.7% of family doctor team workers reported occupational stress. The average score of occupational identity was (3.68±0.62) points. There were significant differences in occupational identity scores among different professional title, work contract, working years in medical institutions, income, and effort/reward ratio (EER) groups (P < 0.05). ERR was negatively correlated with occupational identity (rs=−0.495, P<0.05）. The multiple regression model showed that occupational identity score in the non-staffed participants was lower than the score in the staffed ones (OR=0.429, 95%CI: 0.299−0.825). The occupational identity score in the participants having associate senior title or above was higher than in without professional title (OR=1.424, 95%CI: 1.194−2.328). The longer the working years, the higher the occupational identity score among the participants. The score of the more than 20 working years group was 1.820 times that of the less than 5 working years group (95%CI: 1.342−2.543). The higher the income, the higher the occupational identity score. The score of the 9001−12000 yuan per month group was 1.977 times that of the 1000−3000 yuan per month group (95%CI: 0.811−9.696) , and the score of the more than 12000 yuan per month group was 2.283 times that of the 1000−3000 yuan per month group (95%CI: 1.199−10.267）. ConclusionThe family doctor team workers generally report occupational stress, and their occupational identity is at a medium level in Chengdu. Relevant managers should implement intervention measures against the main influencing factors to reduce their work tension and improve their occupational identity

RingMo-lite: A Remote Sensing Multi-task Lightweight Network with CNN-Transformer Hybrid Framework

In recent years, remote sensing (RS) vision foundation models such as RingMo have emerged and achieved excellent performance in various downstream tasks. However, the high demand for computing resources limits the application of these models on edge devices. It is necessary to design a more lightweight foundation model to support on-orbit RS image interpretation. Existing methods face challenges in achieving lightweight solutions while retaining generalization in RS image interpretation. This is due to the complex high and low-frequency spectral components in RS images, which make traditional single CNN or Vision Transformer methods unsuitable for the task. Therefore, this paper proposes RingMo-lite, an RS multi-task lightweight network with a CNN-Transformer hybrid framework, which effectively exploits the frequency-domain properties of RS to optimize the interpretation process. It is combined by the Transformer module as a low-pass filter to extract global features of RS images through a dual-branch structure, and the CNN module as a stacked high-pass filter to extract fine-grained details effectively. Furthermore, in the pretraining stage, the designed frequency-domain masked image modeling (FD-MIM) combines each image patch's high-frequency and low-frequency characteristics, effectively capturing the latent feature representation in RS data. As shown in Fig. 1, compared with RingMo, the proposed RingMo-lite reduces the parameters over 60% in various RS image interpretation tasks, the average accuracy drops by less than 2% in most of the scenes and achieves SOTA performance compared to models of the similar size. In addition, our work will be integrated into the MindSpore computing platform in the near future

Determination of reference intervals of serum levels of human epididymis protein 4 (HE4) in Chinese women

The detailed numbers of subjects from different centers. (DOCX 17.3 kb

A Sustainable Ethanol Distillation System

The discarded fruit and vegetable waste from the consumer and retailer sectors provide a reliable source for ethanol production. In this paper, an ethanol distillation system has been developed to remove the water contents from the original wash that contains only around 15% of the ethanol. The system has an ethanol production capacity of over 100,000 liters per day. It includes an ethanol condenser, a wash pre-heater, a main exhaust heat exchanger as well as a fractionating column. One unique characteristic of this system is that it utilizes the waste heat rejected from a power plant to vaporize the ethanol, thus it saves a significant amount of energy and at the same time reduces the pollution to the environment

MiR-497-5p promotes osteogenic/odontogenic differentiation of stem cells from the apical papilla by regulation of the TGF-β Smad pathway through Smurf2

Purpose: To study the influence of miR-497-5p on osteogenic/odontogenic differentiation (OOD) of SCAP, and the signal route involved. Methods: Four groups were set up: miR-497-5p overexpression group (OEG), overexpression control OEC), miR-497-5p inhibition group, and inhibition control group. Alkaline phosphatase (ALP) activity was assayed, and calcified nodules measured. Protein expression levels of dentine salivary phosphoprotein (DSPP), collagen type I, ALP, osteoblast-related factors (Runx2, OSX and OPN) were also assayed. The mRNA expression levels of osteogenesis/dentin-related genes were determined. Results: ALP activity was significantly higher in miR-497-5p overexpression cells than in control, but was reduced, relative to inhibition control group (p &lt; 0.05). The miR-497-5p OEG had significantly more calcified nodules than OEC (p &lt; 0.05). There were markedly up-regulated protein expressions in cells of miR-497-5p OEG than in OCG. Furthermore, protein expressions of Smad2, Smad3 and Smad4 in cells of miR-497-5p OEG were significantly up-regulated, relative to those in OEC, but wer lower in miR-497- 5p inhibitory cells than in inhibitory cells. Conclusion: MiR-497-5p enhances the OOD of SCAP via a mechanism involving TGF-β Smad pathway and Smurf2. Thus, Mir-497-5p may be used as a target for OOD-related drugs