Identification of Preferential Recharge Zones in Karst Systems Based on the Correlation between the Spring Level and Precipitation: A Case Study from Jinan Spring Basin

The Jinan spring basin is located in the karst area of northern China, where springs serve as important sources of water supply. Several studies on spring protection and water supply have been carried out, and scholars have developed some laws on local groundwater flow dynamic and characteristics of aquifer structures. Unfortunately, there is a lack of detailed research on preferential recharge zones, which are the main recharge pathways of springs. Therefore, this research focuses on identifying preferential recharge zones based on the correlation between the spring level and precipitation. The results show that when precipitation is more intense or lasts longer, there is a stronger correlation between spring level and precipitation. It has been established that the precipitation at Donghongmiao station has the closest relationship with the dynamic of Baotu spring, which is found to be the most significant contribution to spring preservation. Two potential preferential recharge zones in the Jinan spring basin are detected through correlation analysis and geological exploration data. These findings support spring protection and water supply projects in karst regions.

Recipient Venule Selection and Anastomosis Configuration for Lymphaticovenular Anastomosis in Extremity Lymphedema: Algorithm Based on 1,000 Lymphaticovenular Anastomosis

Background The lymphaticovenular anastomosis (LVA) has three components, lymphatics, venules, and anastomosis, and all of them influence the anastomotic pressure gradient. Although it has been demonstrated that venule flow dynamics has an independent impact on the outcomes regardless the degeneration status of lymphatic vessels, recipient venules (RV) have been mainly neglected in literature. Patients and Methods From January 2016 to February 2020, 232 nonconsecutive patients affected by extremity lymphedema underwent LVA, for a total of 1,000 LVAs. Only patients with normal-to-ectasic lymphatic collectors were included to focus the evaluation on the RV only. The preoperative collected data included the location, diameter, and continence of the selected venules, the expected number, the anastomoses configuration, and their flow dynamics according to BSO classification. Results The 232 patients included 117 upper limb lymphedema (ULL) and 115 lower limb lymphedema (LLL). The average size of RV was 0.81 ± 0.32 mm in end-to-end (E-E), 114 ± 0.17 mm in end-to-side (E-S), 0.39 ± 0.22 mm in side-to-end (S-E), and 0.76 ± 0.38 mm in side-to-side (S-S) anastomoses. According to the BSO classification, on a total of 732 RV, 105(14%) were backflow venules, 136 (19%) were slack, and 491 (67%) were outlet venules. Also, 824 (82%) were E-E, 107 (11%) were E-S, 51 (5%) were S-E, and 18 (2%) were S-S anastomoses. Conclusion Based on 1,000 LVAs with similar lymphatic characteristics, we propose our algorithm that may aid the lymphatic microsurgeon in the selection of RV and the consequent anastomosis configuration, in order of obtain the best flow dynamic through the LVA. This therapeutic study reflects level of evidence IV.

Relationship among Welding Defects with Convection and Material Flow Dynamic Considering Principal Forces in Plasma Arc Welding

The material flow dynamic and velocity distribution on the melted domain surface play a crucial role on the joint quality and formation of welding defects. In this study, authors investigated the effects of the low and high currents of plasma arc welding on the material flow and thermodynamics of molten pool and its relationship to the welding defects. The high-speed video camera (HSVC) was used to observe the convection of the melted domain and welded-joint appearance. Furthermore, to consider the Marangoni force activation, the temperature on the melted domain was measured by a thermal HSVC. The results revealed that the velocity distribution on the weld pool surface was higher than that inside the molten weld pool. Moreover, in the case of 80 A welding current, the convection speed of molten was faster than that in other cases (120 A and 160 A). The serious undercut and humping could be seen on the top surface (upper side) and unstable weld bead was visualized on the back side (bottom surface). In the case of 160 A welding current, the convection on the weld pool surface was much more complex in comparison with 80 A and 120 A cases. The excessive convex defect at the bottom side and the concave defect at the top surface were observed. In the case of 120 A welding current, two convection patterns with the main flow in the backward direction were seen. Almost no welding defect could be found. The interaction between the shear force and Marangoni force played a solid state on the convection and heat transportation processes in the plasma arc welding process.

Relationship Among Welding Defects with Convection and Material Flow Dynamic Considering Principal Forces in Plasma Arc Welding

The material flow dynamic and velocity distribution on the melted domain surface play a crucial role on the joint quality and formation of welding defects. In this study, authors investigated the effects of the low and high currents of plasma arc welding on the material flow and thermodynamics of molten pool and its relationship to the welding defects. The high-speed video camera (HSVC) was used to observe the convection of the melted domain and welded-joint appearance. Furthermore, to consider the Marangoni force activation, the temperature on the melted domain was measured by a thermal HSVC. The results revealed that the velocity distribution on the weld surface was higher than that inside the molten weld pool due to the difference of the massive density between the air and the steel. Moreover, in the case of low welding current (80A) the convection speed of molten was faster than that of the high welding current case (160A) owing to the difference of main driving forces direction and strength, which leading to undercut and humping defects on the weld surface and excessive convex (burn-through) defect at the bottom weld side, respectively. The medium welding current (120A) had two convection patterns with the main flow in backward direction, which resulted in better welding quality without defect. The interaction between the shear force and Marangoni force played a solid state on the convection and heat transportation processes in the plasma arc welding process.

Flow Dynamic Analysis by Contrast-Enhanced Imaging Techniques of Medium Cutoff Membrane Hemodialyzer

<b><i>Introduction:</i></b> Medium cutoff (MCO) membranes represent an interesting innovation in the field of hemodialysis. Given the correlation between large (PM &#x3e;25 kDa) middle molecules (LMM) and clinical outcomes, the possibility to broaden the spectrum of solutes removed in hemodialysis with MCO membranes introduces a new perspective for end-stage kidney disease patients. Due to low diffusion coefficients of LMM, the use of convection is required to maximize extracorporeal clearance. High convective rates are achieved with high-flux membranes in hemodiafiltration, a technique not available in the US. In case of the MCO membrane, remarkable clearances of LMM are achieved combining the permeability of the membrane with a significant amount of internal convection. The mechanism of filtration-backfiltration inside the dialyzer enables effective removal of LMM in a technique called expanded hemodialysis (HDx). Given such theoretical explanation, it is important to demonstrate the blood and ultrafiltration rheology inside the MCO dialyzer. <b><i>Method:</i></b> This study for the first time describes flow dynamic parameters and internal cross-filtration, thanks to specific radiology and nuclear imaging techniques. <b><i>Results:</i></b> Flow dynamic analysis of the blood and dialysate compartment confirms excellent distribution of velocities and an excellent matching of blood and dialysate. Average blood flow velocity allows for wall shear rates adequate to avoid protein stagnation at the blood membrane interface and increase in blood viscosity. Cross-filtration analysis demonstrates a remarkable filtration/backfiltration flux reaching values &#x3e;30 mL/min at a blood flow of 300 mL/min and zero net filtration. <b><i>Conclusion:</i></b> The MCO dialyzer Theranova 400 appears to have a design optimized to perform expanded hemodialysis (HDx).

Experimental studies of vibrations of flexible structures induced by axial pipe flow

This thesis presents experimental studies of vibration of a straight beam and a thin plate in axial pipe flow. Dynamic behaviors of the two structures are investigated for a wide range of mean flow velocities. Responses of the structures were measured and analyzed in the time and frequency domains with an aim to understand the fluid-solid interactions. The experimental results reveal that high mean flow velocities can excite higher vibration modes because of turbulence.

Experimental studies of vibrations of flexible structures induced by axial pipe flow

This thesis presents experimental studies of vibration of a straight beam and a thin plate in axial pipe flow. Dynamic behaviors of the two structures are investigated for a wide range of mean flow velocities. Responses of the structures were measured and analyzed in the time and frequency domains with an aim to understand the fluid-solid interactions. The experimental results reveal that high mean flow velocities can excite higher vibration modes because of turbulence.