Search

Temperature has a significant effect on the performance of elastohydrodynamic lubrication (EHL), and this topic has been extensively covered in many studies. These studies are focused on how temperature affects lubrication performance, without considering the effect of temperature on the deformation and the subsurface stress of the contact bodies. However, there will be a significant rise in temperature in the contact area under such conditions as high speeds, heavy loads, and high slide-roll ratios. This will generate significant thermal stress inside the solid, thus inhibiting the elastic deformation of the contact surface and impairing the lubrication performance in the contact area. In such cases, it is essential to consider the effects of solid thermal stress and thermal expansion on thermal elastohydrodynamic lubrication (TEHL). In this paper, a TEHL model that consider solid thermal expansion and thermal stress to solve point contact problems is developed. The effects of solid thermal expansion and thermal stress on pressure, film thickness, temperature, and subsurface stress are investigated. The results show that solid thermal expansion partially inhibits the elastic deformation of the contact surface, resulting in a decrease in film thickness and an increase in pressure. It is also found that solid thermal stress causes the subsurface von Mises stress of the upper contact body to increase and that of the lower contact body to decrease.

Purpose The cleaning of food production equipment using cleaning detergents may contaminate the lubricant of the bearings, thereby reducing the bearing service life. The purpose of this paper is to investigate the cause and mechanism of such damage of bearings lubricated by cleaning detergent/water-in-oil emulsions. Design/methodology/approach The emulsion was prepared by adding a mixture of cleaning detergent and water in one base oil. A self-designed ball-on-disc optical interference test rig was applied to examine the effect of emulsion on lubrication and wear of bearing contacts under pure sliding conditions. Findings The emulsion reduced lubricating film thickness at a relatively low-sliding speed but only when the water concentration (20%) in emulsion was high. Water droplets were trapped around the ball-on-disc contact area under static conditions because of a high capillary force. The emulsion can induce damages on the soft surface in the startup mainly due to the presence of water around the contact. Originality/value The basic lubrication behaviour of water/oil emulsions containing cleaning detergent under pure sliding was experimental studied and the mechanism of bearing damage in food production equipment was investigated. Based on the study, the solution to avoid such damage was proposed.

Background. Regional analgesia for tubeless, uniport, thoracoscopic wedge resection of benign peripheral nodules is generally performed by intercostal nerve block (INB). We examined the effectiveness of thoracic paravertebral block (PVB), in comparison to the traditional intercostal blocks, for the procedure. Methods. Between July 2016 and December 2016, 20 consecutive patients with solitary benign peripheral lung nodules underwent tubeless uniport thoracoscopic wedge resection using thoracic PVB (PVB group). The clinical outcomes were compared with those of 20 other consecutive patients who underwent the same procedure under the conventional INB, between January 2016 and July 2016 (INB group). In both groups, the procedures were performed without endotracheal intubation, urinary catheterization, or chest tube drainage. Results. The clinical data of patients in both groups were comparable in terms of demographic and baseline characteristics, operative and anesthetic characteristics, puncture-related complications, and postoperative anesthetic adverse events. No puncture-related complications occurred during the perioperative period in either group. The threshold values for mechanical pain at postoperative hours 4 and 8 were significantly higher in the PVB group than in the INB group. Furthermore, the incidence of nausea or vomiting in the PVB group was significantly less than that in the INB group. None of the patients required reintervention or readmission to our hospital. Conclusions. Tubeless uniportal thoracoscopic wedge resection for solitary benign peripheral lung nodules using thoracic PVB for regional analgesia is a feasible and safe procedure. Moreover, we found that thoracic PVB is less painful than INB.

Many fast growing cities have designated greenbelts but have failed to maintain them. This is often attributed to weak planning regulations, but there is little understanding of the underlying impacts of greenbelts on the interactions among land use control, transport supply and economic activities. This paper presents a counterfactual analytical model to examine the greenbelts’ impacts on consumers’ utility, producers’ productivity, and their locational choices. The model establishes historic-what-if scenarios and compares what historically happened with what could have happened under alternative levels of greenbelt interventions. The model is applied to Beijing, which intended to establish two greenbelts in 1994, but large parts of the greenbelts have disappeared under fast urban expansion. The model compares the economic impacts of the greenbelts as they stood with hypothetical fully-enforced greenbelts and no-greenbelt scenarios from 1990 to 2010. The modelling results show that the two greenbelts, if fully enforced, would have decreased consumer surplus by $202 million in Beijing in 2010. To fulfil the policy aim of decentralisation, transport improvements between the city and new towns are crucial. For a more effective implementation of greenbelts in the future, development constraints could be carefully removed from non-ecologically sensitive sites which are served with good transport conditions., Cambridge Overseas Trust China Scholarship Council special fund of Key Laboratory of Eco Planning & Green Building, Ministry of Education (Tsinghua University), China Capco Future Cities Fellowship, Cambridge Real Estate Research Centre The Cambridge-UC Berkeley-National University of Singapore University Alliance project ’Smart Design’

With the popularization and application of chemical process safety management (PSM) systems in the chemical industry, the use of such systems in China has become the focus of a large volume of research. In this article, 12 elements included in the current Chinese PSM system are divided into four stages from a structural point of view. This division will be helpful in the follow-up analysis. After a careful analysis of the evaluation results for one PSM pilot study in Nanjing, some correlations have been found between the results of the elemental evaluation. Small- and medium-sized chemical plants make up a large proportion of Chinese chemical plants and many chemical accidents take place in these plants, so a simplified PSM system in practical operation need to be found. Based on a previous PSM structural analysis, the secondary elements of the PSM system can be removed. This allows researchers to avoid the traditional method of analyzing PSM elements individually. In the concrete analysis process, a theoretical analysis of the correlation degree between elements can be combined with the results of accident investigations. The simplified Chinese PSM system consists of four core elements: Process safety information, process hazard analysis, training, and emergency management. Based on the current applications of these four core elements in China, a consideration of correlations between these elements is used to make several suggestions for improving China's PSM systems. © 2017 American Institute of Chemical Engineers Process Saf Prog, 2017

The high level of reactive oxygen species and up-regulation of mitochondrial fission protein dynamin-related protein-1, both of which involved in pulmonary artery smooth muscle cells (PASMCs) apoptosis, have been detected in the lungs of rodent pulmonary arterial hypertension models. However, the regulatory mechanisms between ROS and DRP1 are poorly understood. In this study, ROS inhibitor, hypoxic rodent PAH models, small interfering RNA, polymerase chain reaction, Western blot, flow cytometry, immunohistochemistry and immunofluorescence were used. We determined that ROS, mainly derive from mitochondria, mediate mitochondria fission of PASMCs contributing to pulmonary vascular remodeling. Meanwhile, we also observed that hypoxia-induced DRP1 expression depends on ROS generation, especially mitochondrial ROS (mROS). Moreover, the levels of ROS and mROS evoked by hypoxia were regulated by DRP1. Furthermore, we verified the apoptosis suppression of PASMCs under hypoxia due to the interaction between ROS/mROS and DRP1. Our study reveals a novel mechanism of hypoxia-induced pulmonary vascular remodeling, suggesting a new therapeutic strategy which is targeting on the positive feedback of ROS/mROS-DRP1 for the treatment of PAH.