We report on the multicontact frictional dynamics of model elastomer surfaces rubbed against bare glass slides. The surfaces consist of layers patterned with thousands of spherical caps distributed both spatially and in height, regularly or randomly. Use of spherical asperities yields circular microcontacts whose radii are a direct measure of the contact pressure distribution. Optical tracking ...

Despite the fact that phyllosilicates are ubiquitous in mature fault and shear zones, little is known about the strength of phyllosilicate-bearing fault rocks under brittle–ductile transitional conditions where cataclasis and solution-transfer processes are active. In this study we explored steady-state strength behaviour of a simulated fault rock, consisting of muscovite and halite, using brin...

In the present study plate-impact pressure-shear friction experiments are conducted to study dynamics of high-speed slip at metal-on-metal interfaces. By using a CH tool-steel/Ti–6Al–4V tribo-pair and appropriate selection of the flyer and target plate thicknesses, the experiment has been used to investigate the frictional resistance of sliding interfaces subjected to step changes in slip rates...

The local head loss of tee could be calculated with the determination of local resistance coefficient by CFD simulation and test. Based on the mesh-independent feature identified, the flow field inner tee was numerically simulated by the standard k ε turbulent model and SIMPLEC algorithms, which has revealed the mainstream was obliged to turn to the opposite side of tee junction, and a rise in ...

Drilling boreholes is common practice in geotechnical and geoenvironmental investigations and in various other ex­ ploration, testing, and monitoring appli­ cations. When a casing is placed in a borehole an annular space is created be­ tween the casing and the surrounding soil. If not properly sealed, this annular space can be a potential path for trans­ port of contaminants in the subsurface e...

Open caisson shafts are a widely adopted solution for range of geotechnical applications. An external ‘cutting shoe’ is common construction feature used to reduce the soil frictional resistance acting on during sinking. This forms an annular void encircling which filled with support fluid maintain excavation stability. The primary aim this paper explore influence cutting shoe geometry resulting...

Pressure sores are localized areas of tissue breakdown in skin and/or underlying tissue. They are painful, difficult to treat, and represent a burden to the community in terms of health care and money. Massive efforts to prevent pressure sores have not resulted in a reduction of the prevalence. This is at least partly due to a lack of understanding of the etiology of pressure sores. The goal of...

BACKGROUND The role of exercise-induced pulmonary hypertension in decision making regarding surgical timing for asymptomatic chronic mitral regurgitation is controversial. We reasoned that the exercise-induced pulmonary hypertension response could not be interpreted without knowledge of right ventricular (RV) function. The aim of this study was to assess the role of RV measures at rest and duri...

BACKGROUND The prevalence and clinical significance of right ventricular (RV) systolic dysfunction (RVD) in patients with heart failure and preserved ejection fraction (HFpEF) are not well characterized. METHODS AND RESULTS Consecutive, prospectively identified HFpEF (Framingham HF criteria, ejection fraction ≥50%) patients (n=562) from Olmsted County, Minnesota, underwent echocardiography at...

Pressure control drilling technology through the precise control of the entire wellbore annular pressure profile, the bottom of the pressure can always maintain the safety density window, so as to achieve the purpose of safe operation. In the drilling process, the use of conventional drilling technology for drilling operations, easily lead to well, overflow and other drilling accidents. In this...