Search

In this paper, a numerical simulation study of flow and heat transfer in a grooved channel consisting of ten rectangular grooves with steady and pulsating flow is carried out. Numerical simulations of the steady flow with small perturbations applied at Re = 800, 1200, 1600, and 2000 show that the same intrinsic frequency fN exists at different positions, amplitudes, and durations, and it disappears gradually with the development of the flow. A sinusoidal pulsating flow with different frequencies is applied to the grooved channel with the dimensionless amplitude A fixed at 0.2. The flow and heat transfer properties of the grooved channel are investigated in the case of pulsating inflow, and it is found that there exists a vortex periodic formation–development–convergence–dissipation process inside each groove. The results show that the increase in the time-averaged Nusselt number is 44.12%, 57.75%, 53.21%, 52.93%, the time-averaged friction factor is increased by 58.23%, 133.04%, 140.80%, 151.26%, and the PECs is decreased with the increase in Reynolds number to be 1.24, 1.19, 1.14, and 1.12, respectively, when compared with the constant flow. When the forcing frequency is equal to the hydrodynamic instability frequency, the time-averaged Nusselt number of the grooved channel will reach its maximum value. Also, the dynamic mode decomposition analysis shows that the pulsation mode energy is maximum when the forcing frequency is equal to the hydrodynamic instability frequency. It shows that the applied pulsating flow has a positive effect of enhanced heat transfer, and the positive effect decreases with the increase in Reynolds number. [ABSTRACT FROM AUTHOR]

In view of problems such as the narrow efficiency area, large hydraulic vibration area, pressure pulsation, and serious sediment wear of turbines at the Futang hydropower station, the technical transformation of turbine runners was carried out by modifying the blade shape and increasing the blade thickness, and a combination of numerical simulations based on shear stress transport k–ω turbulence model and tests was adopted to improve the operational stability of power station units. Calculation and testing demonstrate an enlargement of the high‐efficiency zone. Specifically, the optimal efficiency of the runner increases by 0.37%, while the rated efficiency rises by 0.19%. Significant reductions are observed in pressure pulsation within the draft tube and vaneless area decrease of approximately 50%. There is a high‐frequency pressure pulsation in the vaneless zone and the runner under low‐load conditions, and the influence of dynamic and static interference gradually weakens with the increase of opening. The draft tube is prone to eccentric vortex bands under partial working conditions, which causes the unit to be affected by low‐frequency pulsation. This optimization also leads to a notable decrease in runner blade wear, with the maximum sand and water velocity reduced from 45 to 40 m/s, resulting in a 30% reduction in sand wear. Moreover, there is a substantial enhancement in the runner's stiffness, with the thickness of the blade near the high stress area of the upper crown and lower ring increasing by over 50%, and the weight of each individual blade increasing by more than 50%. These research findings validate that modifying the runner blade effectively improves flow patterns, reduces eddy current generation, minimizes pressure pulsation, widens the high‐efficiency zone, decreases wear, and enhances the operational stability of the unit. The technical transformation method and research results of this study have important guiding significance for similar technical transformation of other power stations [ABSTRACT FROM AUTHOR]

Discoidin, CUB, LCCL domain‐containing 2 (DCBLD2) is a type I transmembrane protein with a similar structure to neuropilin, which acts as a co‐receptor for certain receptor tyrosine kinases (RTKs). The insulin receptor is an RTK and plays a critical role in endothelial cell function and glycolysis. However, how and whether DCBLD2 regulates insulin receptor activity in endothelial cells is poorly understood. Diabetes was induced through treatment of Dcbld2 global‐genome knockout mice and endothelium‐specific knockout mice with streptozotocin. Vascular ultrasound, vascular tension test, and hematoxylin and eosin staining were performed to assess endothelial function and aortic remodeling. Glycolytic rate assays, real‐time PCR and western blotting were used to investigate the effects of DCBLD2 on glycolytic activity and insulin receptor (InsR)/phosphatidylinositol 3‐kinase (PI3K)/protein kinase B (Akt) pathway in endothelial cells. Co‐immunoprecipitation was used to assess the effects of DCBLD2 on insulin receptor endocytosis and recycling. Membrane and cytoplasmic proteins were isolated to determine whether DCBLD2 could affect the localization of the insulin receptor. We found that Dcbld2 deletion exacerbated endothelial dysfunction and vascular remodeling in diabetic mice. Both Dcbld2 knockdown and Dcbld2 deletion inhibited glycolysis and the InsR/PI3K/Akt signaling pathway in endothelial cells. Furthermore, Dcbld2 deletion inhibited insulin receptor recycling. Taken together, Dcbld2 deficiency exacerbated diabetic endothelial dysfunction and vascular remodeling by inhibiting the InsR/PI3K/Akt pathway in endothelial cells through the inhibition of Rab11‐dependent insulin receptor recycling. Our data suggest that DCBLD2 is a potential therapeutic target for diabetes and cardiovascular diseases. [ABSTRACT FROM AUTHOR]

The Yushu fault, part of the Yushu–Ganzi fault zone, is one of several E‐W‐trending left‐lateral, strike‐slip fault zones that extend across the Tibetan Plateau accommodating lateral transfer of crustal material out of the collision zone between the Indian and Eurasian plates. Discontinuous left‐lateral surface rupture occurred along WNW‐ESE‐striking, near‐vertical faults during two Mw 6.9 14 April 2010 Yushu earthquakes. Geomorphic and surface‐rupture characteristics change at the base of a red cliff separating the Guoqiong and Buqionggei segments. Excavations across these segments near the Jinsha River show: (a) more continuous deposition on the down‐dropped side; and (b) how frequently these surface‐rupture histories were linked or sequential (major to great earthquakes) versus not linked (moderate/strong to large earthquakes). Trench CUG‐2011‐1 and roadcut CUG‐2012‐1 (Guoqiong segment) were on older fan surfaces and Trench CUG‐2012‐2 (Buqionggei segment) crossed a narrow graben. On the Guoqiong segment, using OxCal v.4.4 that works with IntCal20 database for Bayesian‐ordered ages from four 14C and nine OSL ages, surface ruptures occurred during earthquakes at 2010CE, ∼200BCE, ∼2400BCE, ∼4250BCE, ∼6750BCE, ∼7400BCE and ∼10400BCE consistent with an ∼2200‐year Holocene recurrence interval. For the Buqionggei segment, Bayesian‐ordered ages from six OSL ages indicate three Holocene surface ruptures occurred at 2010CE, ∼4600BCE and ∼6750BCE. Surface ruptures on both segments (suggesting linked or sequential major to great earthquakes) only occurred two to three times at 2010CE, ∼4500BCE and/or ∼6750BCE. Thus, risk of infrequent major to great Holocene earthquakes is ∼2400–∼8800 years along the Yushu fault. Plain Language Summary: We dug trenches across the Yushu fault near Guoqingyi Rodgsongdub where surface rupture related to 2010 Yushu earthquake first crosses the Jinsha River. Left lateral slip‐slip, surface rupture diminishes from 2.1 m in wide terraces and the floodplain just west of the river to 0.2 m across the narrow youngest late Holocene terrace east of the river. Thus, the river roughly separates two different segments of the Yushu fault. To the west, seven surface ruptures occurred regularly every ∼2200 years for the last 12000 years. To the east, three irregularly spaced surface ruptures occurred over the same time. We suggest stronger earthquakes (i.e., 2010 Yushu earthquake) occur when both segments lock and rupture as Major to Great earthquakes whereas unlocked Moderate to Large earthquakes occur when only one segment ruptures. Key Points: Earthquake characteristics change across a segment boundary of the active Yushu faultWest of where the Jinsha River first crosses the Yushu fault, seven surface ruptures occurred regularly every ∼2200 years for the last ∼12000 years; east of the river's terraces, only three irregularly spaced surface ruptures occurred over the same time periodWe suggest stronger earthquakes (e.g., 2010 Yushu earthquake) occur when both segments rupture as Major to Great earthquakes whereas only Moderate to Large earthquakes occur when only one segment ruptures [ABSTRACT FROM AUTHOR]