Dynamic modeling of ultra-precision fly cutting machine tool and the effect of ambient vibration on its tool tip response

The dynamic performances of an ultra-precision fly cutting machine tool(UFCMT)has a dramatic impact on the quality of ultra-precision machining.In this study,the dynamic model of an UFCMT was established based on the transfer matrix method for multibody systems.In particular,the large-span scale flow field mesh model was created;and the variation in linear and angular stiffness of journal and thrust bearings with respect to film thickness was investigated by adopting the dynamic mesh technique.The dynamic model was proven to be valid by comparing the dynamic characteristics of the machine tool obtained by numerical simulation with the experimental results.In addition,the power spectrum density estimation method was adopted to simulate the statistical ambient vibration excitation by processing the ambient vibration signal measured over a long period of time.Applying it to the dynamic model,the dynamic response of the tool tip under ambient vibration was investigated.The results elucidated that the tool tip response was significantly affected by ambient vibration,and the isolation foundation had a good effect on vibration isolation.

Distress Assessment and Response Systems in Patients With Cancer Pain

Objective This study used the Distress Assessment and Response Tool(DART)to screen,evaluate,and explore physical symptoms,psychological problems,and social support in patients with cancer pain,with an aim to provide data for the comprehensive care of these patients to improve their quality of life.Methods The DART was used to survey 497 patients with cancer pain who were admitted to the Cancer Center of the First Hospital of Jilin University from June 2014 to March 2017.All patients were diagnosed with malignant tumors by clinical,radiological and/or cytological examinations,and were experiencing tumor-related pain.This study recorded the patient’s somatic symptoms,psychological problems and social support in detail.After the data were collected,the SPSS 21.0 software was used to perform the statistical analysis,with the significance level set at P<0.05.Results In total,82.7%of patients were experiencing mild pain(NRS≤3);of these,29.7%and 15.8%reported depression and anxiety,respectively.In addition,17.3%of patients were experiencing moderate or severe pain(NRS≥4);of these,53.5%and 40.7%reported depression and anxiety,respectively.There was a statistically significant difference in the incidence of anxiety and depression between the two groups.Conclusion Patients with cancer pain,particularly those with moderate-to-severe pain,showed a high incidence of distress.In addition,they were likely to report physical symptoms,were conscious of poor health conditions,and were prone to have anxiety and depression.In terms of social support,patients with moderate-to-severe cancer pain should receive substantial support,as they experience work-related and economic concerns and report difficulties in family life and social activities.