The failure of a drilling pump is always due to the break of the drilling pump valve, which is one of the most important but also the weakest parts of the drilling pump. Over the decades, the degradation of drilling p...The failure of a drilling pump is always due to the break of the drilling pump valve, which is one of the most important but also the weakest parts of the drilling pump. Over the decades, the degradation of drilling pump valves has been investigated extensively and various failure mechanisms have been proposed. However, no experimental test on the fluid has been successfully performed to support some of these mechanisms. In this paper, tests of the flow within the valve play are carried out to investigate the factors resulting in the failure of the valve. In the tests, particle image velocimetry（PIV） technology is employed to measure the flow field distribution of the valve play in the model. From these tests, the distributions of velocity and vorticity of fluid in ＇various valves with different valve angles and different valve lifts are obtained, from which the features of flow fields are derived and generalized. Subsequently, a general rule of the influence of valve angles and valve lifts on the flow velocity is concluded according to chart analyses of maximal velocities and mean velocities. Finally, an analysis is made on the possibility of valve failure caused by erosion and abrasion in a working valve, with the application of the failure mechanisms of drilling pump valves. PIV measurement improves the study on the failure of the drilling pump valve, and the results show good agreement with previous computational fluid dynamics（CFD） simulations.展开更多
文摘目的研究胶原肽联合钙尔奇D对绝经后骨质疏松患者的疗效。方法 202例绝经后骨质疏松症患者随机分为试验组(每日口服胶原肽10 g联合钙尔奇D 600 mg)和对照组(口服钙尔奇D 600 mg),进行为期6个月的治疗。利用化学发光法检测血清总骨1型前胶原N端肽(N-propeptide of type 1 collagen,PINP)、β-I型胶原交联羧基末端肽(C-terminal crosslinked telopeptides of type 1 collagen,β-CTX)、血清骨钙素(osteocalcin,OC)、25-羟维生素D3[25 hydroxy vitamine D3,25(OH)D3]、甲状旁腺素(parathyroid hormone,PTH)。利用双能X线(dual energy X-ray absorptiometry,DXA)吸收法进行腰椎、股骨骨密度(bone mineral density,BMD)检测。结果治疗6个月后,口服胶原肽联合钙尔奇D能够更有效地缓解骨质疏松导致的骨痛。试验组患者血清PTH、25(OH)D3及OC水平明显高于治疗前(P<0.01)及对照组(P<0.01)。对照组患者治疗后血清PINP水平明显低于治疗前(P<0.01),而PTH、25(OH)D3、β-CTX水平明显高于治疗前(P<0.01)。试验组患者治疗后血清PINP水平明显高于对照组(P<0.01),而β-CTX水平低于对照组(P<0.05)。试验组患者腰椎L_2、L_4及股骨颈、粗隆间BMD明显高于治疗前(P<0.01)及对照组(P<0.05)。试验组患者各部位BMD均显著高于治疗前(P<0.01);而对照组患者治疗后上述各指标差异无统计学意义(P>0.05)。结论口服胶原肽联合钙尔奇D既能促进骨形成,又能抑制骨吸收,进一步增加BMD,并且可以缓解骨质疏松引起的疼痛。
基金supported by National Natural Science Foundation of China (Grant No. 50575017, Grant No. 50875016)
文摘The failure of a drilling pump is always due to the break of the drilling pump valve, which is one of the most important but also the weakest parts of the drilling pump. Over the decades, the degradation of drilling pump valves has been investigated extensively and various failure mechanisms have been proposed. However, no experimental test on the fluid has been successfully performed to support some of these mechanisms. In this paper, tests of the flow within the valve play are carried out to investigate the factors resulting in the failure of the valve. In the tests, particle image velocimetry（PIV） technology is employed to measure the flow field distribution of the valve play in the model. From these tests, the distributions of velocity and vorticity of fluid in ＇various valves with different valve angles and different valve lifts are obtained, from which the features of flow fields are derived and generalized. Subsequently, a general rule of the influence of valve angles and valve lifts on the flow velocity is concluded according to chart analyses of maximal velocities and mean velocities. Finally, an analysis is made on the possibility of valve failure caused by erosion and abrasion in a working valve, with the application of the failure mechanisms of drilling pump valves. PIV measurement improves the study on the failure of the drilling pump valve, and the results show good agreement with previous computational fluid dynamics（CFD） simulations.
