Application of evolution-based uncertainty design on gear

The evolution of mechanical parameters, a factor affecting the mechanical reliability, has gathered more attention nowadays. However, studies on time varying uncertainty can hardly be found. A new method based on evolution-based uncertainty design (EBUD) is applied to the design of gear in this paper. Considering the wear evolution over the lifetime, a tooth wear’s time-varying uncertainty model based on the continuous-time model and Ito lemma is established. Drift and volatility functions dependent on the drift rate and volatility rate of rotational speed and torque are used to express the time-varying uncertainty of tooth thickness. The method can predict the reliability and provide an instruction in reliability improving, maintenance and repair of the gear system

Emotions, COVID-19 related thoughts and satisfaction with life during the critical period from control to relaxation

IntroductionIn the context of declining mortality rates and increasing infectivity, it has become unavoidable for the majority of individuals to experience a COVID-19 infection at some point. This study aimed to investigate the psychological well-being of the general population during China’s transition period from strict control measures to relaxed policies in COVID-19 prevention and control, as well as the impact of COVID-19 related thoughts on emotion and life satisfaction during widespread infections.MethodsA cross-sectional study was conducted involving a sample size of 1578 participants. Participants completed self-report questionnaires assessing positive and negative emotions, thoughts about COVID-19, and satisfaction with life. Demographic characteristics such as sex, age, and education level were controlled for in the analysis.ResultsThe findings revealed that individuals who had been infected with COVID-19 (specifically the Omicron variant BA.5.2 or BF.7) reported lower levels of positive emotions compared to those who were uninfected or had recovered from the infection. There was a significant relationship between COVID-19-related thoughts, emotions, and life satisfaction. Positive COVID-19 related thoughts were found to mediate the relationship between negative emotions and satisfaction with life.DiscussionThis study represents a comprehensive examination conducted in China, focusing on assessing the impact of the COVID-19 pandemic on the general population during the critical transition period from control to relaxation. Throughout this period, the number of infections experienced fluctuations, initially rising but eventually declining over a one-month span. In such a momentous historical period, maintaining a positive perspective on COVID-19 and its management becomes paramount in enhancing the emotional well-being, life satisfaction and overall well-being of individuals

Mesoporous Polydopamine Loaded Pirfenidone Target to Fibroblast Activation Protein for Pulmonary Fibrosis Therapy

Recently, fibroblast activation protein (FAP), an overexpressed transmembrane protein of activated fibroblast in pulmonary fibrosis, has been considered as the new target for diagnosing and treating pulmonary fibrosis. In this work, mesoporous polydopamine (MPDA), which is facile prepared and easily modified, is developed as a carrier to load antifibrosis drug pirfenidone (PFD) and linking FAP inhibitor (FAPI) to realize lesion-targeted drug delivery for pulmonary fibrosis therapy. We have found that PFD@MPDA-FAPI is well biocompatible and with good properties of antifibrosis, when ICG labels MPDA-FAPI, the accumulation of the nanodrug at the fibrosis lung in vivo can be observed by NIR imaging, and the antifibrosis properties of PFD@MPDA-FAPI in vivo were also better than those of pure PFD and PFD@MPDA; therefore, the easily produced and biocompatible nanodrug PFD@MPDA-FAPI developed in this study is promising for further clinical translations in pulmonary fibrosis antifibrosis therapy

STRENGTH ANALYSIS OF SCRAPER BUCKET BASED ON THE COUPLING OF HYPERMESH- EDEM-PATRAN

Bucket force is simplified as concentrated force or uniform force in traditional bucket strength analysis,which will result in inaccurate bucket strength analysis result. Taking Sandvik 1400 e scraper as an example in this paper,carrying out pretreatment on the bucket based on Hyper Mesh,simulating scraper working process by EDEM,it is obtained that bucket is characterized by complication and variable load during scraper operation. By way of coupling discrete element and finite element,bucket was loaded precisely,then bucket strength analysis and wear calculation were completed,which will provide theoretical basis for bucket structure optimization

A Study on the Influence of Bolt Arrangement Parameters on the Bending Behavior of Timber–Steel Composite (TSC) Beams

The present paper investigates the impact of bolt distance, bolt diameter, and the number of bolt rows on the bending performance of timber–steel composite (TSC) beams. This study aims to facilitate the application of bolt connections in assembled TSC structures. Composite steel I-beams were designed with timber boards connected in the upper section with bolts. Three-point static bending tests were conducted on nine timber–steel composite beams divided into four groups (L1, L2, L3, and L4) with varying bolt arrangements. The destruction mode, ultimate bearing capacity, ductility coefficient, load–midspan deflection curve, and load–midspan strain curve of each specimen were obtained. In addition, the destruction mechanism, the quantitative relationship between the bolt area ratio and interfacial slip, and the ideal bolt area ratio were identified. It was found that when the midspan deflection of the timber–steel composite beam approached the prescribed limit, the main failure mode can be explained as follows: The top surface of the boards of all the specimens had longitudinal local splitting, except L1, which had fewer bolts and no obvious damage. Moreover, due to compression and because the stress at the lower edge of the I-beam entered the flow amplitude stage, some of the specimens were crushed but were not pulled off. The composite beams had high flexural load capacity and ductility coefficient, and the maximum relative slips of the timber–steel interfaces were in the range of 2–6 mm. It was also found that the maximum slip of the interface and the ductility coefficient decreased steadily as the bolt area ratio increased, while the specimen’s flexural bearing capacity increased. The optimal bolt area ratio was determined to be 8 × 10−3. Using the total bolt area, we designed the arrangement of the bolts on the board. For convenience, multiple bolt variables were converted into one bolt variable. The longitudinal distance of the bolts had a greater impact on the slip, and the bolt diameter had a smaller impact. The theoretical values of total relative slip were found to be in good agreement with the experimental results, which were based on the superposition of the relative slip equations with varying bolt distances. The effective bolt area ratio and the formula of the relative slip of each segment can provide instructions for the arrangement of bolts and the control of the relative slip of intersections in engineering practices

Performance Analysis and Optimization of a 6-DOF Robotic Crusher

Considering the complexity of multidimension parameters and the mechanical performance of a 6-DOF robotic crusher, a multiobjective optimization function based on the transmission index and condition number is established. As an important operation in the screw theory, the reciprocal product between the transmission wrench screw of an actuator and the output twist screw of the mantle assembly is used to represent the instantaneous power. The expression of transmission index is derived according to the principle that constraint wrench screws apply no work to the mantle assembly. It can be used as a criterion to evaluate the transmission performance. Then, based on the Jacobian matrix, the equation of condition number is constructed which provides a criterion for evaluating kinematic accuracy. Finally, the workspace and singularity of the 6-DOF robotic crusher are analyzed to verify the rationality of the optimized variables. The results show that the optimized structure can completely crush the material in the workspace and effectively avoid singularity, which provides a basis for practical application

Prediction Model for Liner Wear Considering the Motion Characteristics of Material

A generic model to explore the relationship between the parameters of cone crusher and liner wear is provided in this paper. Relative slide and squeezing between material and liner are considered based on the operating conditions, structure parameters, and material properties. The sliding distance of the material under different conditions is discussed. It is detailed how operating parameters and structural parameters influence the pressure on the liner surface. Considering that the process of liner wear evolves over time, the updating method of the geometry of crushing chamber is adopted. The wear model is derived based on Archard theory and is calibrated with the measured wear profiles of the liner from a PYGB1821 cone crusher. Experiments show that the predicted wear amount is consistent with the measured results. The wear model can be used to predict the wear state of liner and quantify the influence of operating parameters and structural parameters on the liner wear

A Study on the Influence of Bolt Arrangement Parameters on the Bending Behavior of Timber–Steel Composite (TSC) Beams

The present paper investigates the impact of bolt distance, bolt diameter, and the number of bolt rows on the bending performance of timber–steel composite (TSC) beams. This study aims to facilitate the application of bolt connections in assembled TSC structures. Composite steel I-beams were designed with timber boards connected in the upper section with bolts. Three-point static bending tests were conducted on nine timber–steel composite beams divided into four groups (L1, L2, L3, and L4) with varying bolt arrangements. The destruction mode, ultimate bearing capacity, ductility coefficient, load–midspan deflection curve, and load–midspan strain curve of each specimen were obtained. In addition, the destruction mechanism, the quantitative relationship between the bolt area ratio and interfacial slip, and the ideal bolt area ratio were identified. It was found that when the midspan deflection of the timber–steel composite beam approached the prescribed limit, the main failure mode can be explained as follows: The top surface of the boards of all the specimens had longitudinal local splitting, except L1, which had fewer bolts and no obvious damage. Moreover, due to compression and because the stress at the lower edge of the I-beam entered the flow amplitude stage, some of the specimens were crushed but were not pulled off. The composite beams had high flexural load capacity and ductility coefficient, and the maximum relative slips of the timber–steel interfaces were in the range of 2–6 mm. It was also found that the maximum slip of the interface and the ductility coefficient decreased steadily as the bolt area ratio increased, while the specimen’s flexural bearing capacity increased. The optimal bolt area ratio was determined to be 8 × 10−3. Using the total bolt area, we designed the arrangement of the bolts on the board. For convenience, multiple bolt variables were converted into one bolt variable. The longitudinal distance of the bolts had a greater impact on the slip, and the bolt diameter had a smaller impact. The theoretical values of total relative slip were found to be in good agreement with the experimental results, which were based on the superposition of the relative slip equations with varying bolt distances. The effective bolt area ratio and the formula of the relative slip of each segment can provide instructions for the arrangement of bolts and the control of the relative slip of intersections in engineering practices