The expansion of a thick-walled hollow cylinder in soil is of non-self-similar nature that the stress/deformation paths are not the same for different soil material points.As a result,this problem cannot be solved by ...The expansion of a thick-walled hollow cylinder in soil is of non-self-similar nature that the stress/deformation paths are not the same for different soil material points.As a result,this problem cannot be solved by the common self-similar-based similarity techniques.This paper proposes a novel,exact solution for rigorous drained expansion analysis of a hollow cylinder of critical state soils.Considering stress-dependent elastic moduli of soils,new analytical stress and displacement solutions for the nonself-similar problem are developed taking the small strain assumption in the elastic zone.In the plastic zone,the cavity expansion response is formulated into a set of first-order partial differential equations(PDEs)with the combination use of Eulerian and Lagrangian descriptions,and a novel solution algorithm is developed to efficiently solve this complex boundary value problem.The solution is presented in a general form and thus can be useful for a wide range of soils.With the new solution,the non-self-similar nature induced by the finite outer boundary is clearly demonstrated and highlighted,which is found to be greatly different to the behaviour of cavity expansion in infinite soil mass.The present solution may serve as a benchmark for verifying the performance of advanced numerical techniques with critical state soil models and be used to capture the finite boundary effect for pressuremeter tests in small-sized calibration chambers.展开更多
The present study concerns the revalorization of drained water from aquaculture ponds rearing Clarias gariepinus on okra crops. The rearing was carried out at the farm of Gaston Berger University in 100 m2 ponds. In e...The present study concerns the revalorization of drained water from aquaculture ponds rearing Clarias gariepinus on okra crops. The rearing was carried out at the farm of Gaston Berger University in 100 m2 ponds. In each pond, the individuals of C. garipinus with an average weight of 6 ± 0.3 g were stocked at a density of 11 per m2. The water temperature and pH were measured during the experiment. The control fishing is carried out every month to monitor variations in the weight and size of reared individuals. The plant production is carried out in elementary plots measuring 3 m × 1.5 m. Each plot was fertilized with either: drained water from C. gariepinus rearing (DWC), poultry droppings (PD), cow dung (CD) and mineral fertilizer (NPK). Treatments are carried out in tripliqua with either river water (RW), RW + the recommended dose of NPK (RD-NPK), RW + RD-PD, RW + RD-CD, DWC, DWC + 25% RD-NPK, DWC + 50% RD-NPK, DWC + 75% RD-NPK, DWC + 25% RD-PD, DWC + 50% RD-PD, DWC + 75% RD-PD, DWC + 25% RD-CD, DWC + 50% RD-CD, DWC + 75% RD-CD. Growth parameters and yield of okra were determined. The average temperature in the rearing environment was 27.6 ± 1.5˚C and pH 7.9 ± 1.1. After six (06) months of rearing, C. gariepinus individuals reached an average weight of 850.12 ± 1.3 g and an average height of 52.44 ± 1.1 cm. The daily weight gain and specific growth rates over this period were 3.9 g per day and 2.8% per day, respectively. The treatment T1 (RW + DR-NPK) gave the highest mean collar diameter and mean plant height with 2.3 ± 0.9 cm and 61.6 ± 32 cm, respectively. In T4 (DWC), the mean height of plants was 38.8 ± 23.5 cm and mean collar diameter 1.4 ± 0.8 cm. The growth performance in T4 was comparable to that of RD-CD (T3), but different from RD-NPK (T1) and RD-PD (T2). The highest average number, average weight, average length and average diameter of fruits were noted in treatments T13 (RW + RD-75%CD) and T7 (DWC + 75% RD-NPK). The best yields were noted in T1 (RW + RD-NPK) = 10.8 ± 5.4 t·ha−1, T5 (DWC + 25% RD-NPK) = 9.2 ± 4.6 t·ha−1 and T4 (DWC) = 8.6 ± 4.3 t·ha−1 which are comparable and higher than those obtained in T2 = 5.7 ± 2.8 t·ha−1 and T3 = 7.5 ± 3.8 t·ha−1.展开更多
Three dimensional （3D） DEM （discrete element method） simulations of drained triaxial compression and plane strain tests are presented for both dense and loose assemblies of polydisperse spheres using a periodic ce...Three dimensional （3D） DEM （discrete element method） simulations of drained triaxial compression and plane strain tests are presented for both dense and loose assemblies of polydisperse spheres using a periodic cell. In the work reported, drained tests were modelled by deforming the samples under constant mean stress conditions. The drained behaviour is shown to be qualitatively similar to published physical experimental results. The Bishop＇s formula for the estimation of the intermediate principal stress is evaluated. The existence of critical density is shown to be independent of initial packing densities and strain conditions. Different failure criteria have been compared based on the DEM simulation results, and the Lade criterion is found to be the most appropriate one. A new microscopic fabric parameter is introduced to give insight to structural anisotropy under general 3D fabric conditions. It is found that two parameters characterize the evolution of the stress and fabric respectively independent of strain conditions.展开更多
A 2D full cell thermo-electric model of 160kA drained cell was set up using finiteelement code to calculate its freeze profile, then the drained cell model was modifiedaccording to the freeze profile computed and its ...A 2D full cell thermo-electric model of 160kA drained cell was set up using finiteelement code to calculate its freeze profile, then the drained cell model was modifiedaccording to the freeze profile computed and its heat balance was calculated. Comparedwith that of a 160kA conventional Hall-Heroult cell (H-H cell), though the melts vol-ume of the drained cell reduced greatly, the whole heat loss from it didn't drop downapparently, and an analysis was presented in the paper. On the other hand, the anode-cathode distance (ACD) of a drained cell was much less than that of a H-H cell, sothe voltage drop on it and heat produced decreased too, steps should be taken to keepa workable heat balance on a drained cell.展开更多
Based on the commercial CFD software CFX-4.3, two-phase flow of electrolyte in 156 kA drained aluminum reduction cells with a new structure was numerically simulated by multi-fluid model and k-ε turbulence model. The...Based on the commercial CFD software CFX-4.3, two-phase flow of electrolyte in 156 kA drained aluminum reduction cells with a new structure was numerically simulated by multi-fluid model and k-ε turbulence model. The results show that the electrolyte flow in the drained cells is more even than in the conventional cells. Corresponding to center point feeding, the electrolyte flow in the drained cells is more advantageous to the release of anode gas, the dissolution and diffusion of alumina, and the gradient reduction of the electrolyte density and temperature. The average velocity of the electrolyte is 8.3 cm/s, and the maximum velocity is 59.5 cm/s. The average and maximum velocities of the gas are 23.2 cm/s and 61.1 cm/s, respectively. The cathode drained slope and anode cathode distance have certain effects on the electrolyte flow.展开更多
The drainage areas(and volumes)near hydraulically fractured wells,computed and visualized in our study at high resolution,may be critically affected by the presence of natural fractures.Using a recently developed algo...The drainage areas(and volumes)near hydraulically fractured wells,computed and visualized in our study at high resolution,may be critically affected by the presence of natural fractures.Using a recently developed algorithm based on complex analysis methods(CAMs),the drained rock volume(DRV)is visualized for a range of synthetic constellations of natural fractures near hydraulic fractures.First,flow interference effects near a single hydraulic fracture are systematically investigated for a variety of natural fracture sets.The permeability contrast between the matrix and the natural fractures is increased stepwise in order to better understand the effect on the DRV.Next,a larger-scale model investigates flow interference for a full hydraulically fractured well with a variety of natural fracture sets.The time of flight contours(TOFCs)outlining the DRV are for all cases with natural fractures compared to a base case without any natural fractures.Discrete natural fractures,with different orientations,hydraulic conductivity,and fracture density,may shift the TOFC patterns in the reservoir region drained by the hydraulically fractured well,essentially shifting the location of the well’s drainage area.The CAM-based models provide a computationally efficient method to quantify and visualize the drainage in both naturally and hydraulically fractured reservoirs.展开更多
Based on the principle of energy conservation,the applicable technique for drained cell retrofitted from conventional one was analyzed with 2D finite element model. The model employed a 1D heat transfer scheme to comp...Based on the principle of energy conservation,the applicable technique for drained cell retrofitted from conventional one was analyzed with 2D finite element model. The model employed a 1D heat transfer scheme to compute iteratively the freeze profile until the thickness variable reached the terminating requirement. The calculated 2D heat dissipation from the cell surfaces was converted into the overall 3D heat loss. The potential drop of the system, freeze profile and heat balance were analyzed to evaluate their variation with technical parameters when designing the 150 kA conventional cell based drained cell. The simulation results show that the retrofitted drained cell is able to keep thermal balance under the conditions that the current is 190 kA, the anodic current density is 0.96 A/cm2, the anode-cathode distance is 2.5 cm, the alumina cover is 16 cm thick with a thermal conductivity of 0.20 W/(m·℃ ) and the electrolysis temperature is 946 ℃ .展开更多
Current distribution in a drained aluminum reduction cell is critical due to its influence on the current efficiency, electrolysis stability, anodes and cathodes integrity. A finite element model was developed to simu...Current distribution in a drained aluminum reduction cell is critical due to its influence on the current efficiency, electrolysis stability, anodes and cathodes integrity. A finite element model was developed to simulate the electric field in a 75 kA drained aluminum reduction cell. The current distribution and influences of the cathode inclination angle and anode-cathode distance (ACD) were studied. The results show that relatively large horizontal current density appears in the aluminum film, and the maximum value reaches 600 kA/m2. As the cathode inclination angle increases from 2° to 15°, the maximum current density of the metal pad increases by 15%, while the maximum current density of the aluminum-wettable coating layer decreases by 27%. The influence of the ACD on the current distribution is not obvious.展开更多
Based on principles of electromagnetic fluid dynamics the exerted forces and movement states of melted aluminum in the traditional reduction cells and the drained cells were compared and analyzed in this paper. And ba...Based on principles of electromagnetic fluid dynamics the exerted forces and movement states of melted aluminum in the traditional reduction cells and the drained cells were compared and analyzed in this paper. And based on the theory of slow movement, a formula in respect of the drained angle was derived, i.e. θ≥(J zB x-J xB z)ρg-(J xB y-J yB x ). It can be seen that the drained slope can be decided by respectively multiplying the area current densities and magnetic induction intensities in three coordinate directions in aluminum reduction cells, and the drained slope is approximate to 0.6% derived from typical data based on measurement and calculation, which implies that the key parameter is obtained in designing of drained cells. The results can be used for a designing basis for drained cathodes.展开更多
This study applies the Lindenmayer system based on fractal theory to generate synthetic fracture networks in hydraulically fractured wells.The applied flow model is based on complex analysis methods,which can quantify...This study applies the Lindenmayer system based on fractal theory to generate synthetic fracture networks in hydraulically fractured wells.The applied flow model is based on complex analysis methods,which can quantify the flow near the fractures,and being gridless,is computationally faster than traditional discrete volume simulations.The representation of hydraulic fractures as fractals is a more realistic representation than planar bi-wing fractures used in most reservoir models.Fluid withdrawal from the reservoir with evenly spaced hydraulic fractures may leave dead zones between planar fractures.Complex fractal networks will drain the reservoir matrix more effectively,due to the mitigation of stagnation flow zones.The flow velocities,pressure response,and drained rock volume(DRV)are visualized for a variety of fractal fracture networks in a single-fracture treatment stage.The major advancement of this study is the improved representation of hydraulic fractures as complex fractals rather than restricting to planar fracture geometries.Our models indicate that when the complexity of hydraulic fracture networks increases,this will suppress the occurrence of dead flow zones.In order to increase the DRV and improve ultimate recovery,our flow models suggest that fracture treatment programs must find ways to create more complex fracture networks.展开更多
Reliable assessment of the lateral pile–soil interaction is of pronounced importance for the design of mono-pile foundations of offshore wind turbines. As the offshore engineering moves to deeper waters, the diameter...Reliable assessment of the lateral pile–soil interaction is of pronounced importance for the design of mono-pile foundations of offshore wind turbines. As the offshore engineering moves to deeper waters, the diameter of monopiles is getting larger, usually about 5 m and could be up to 8 m, which may lead to partially drained behaviors of sand in the vicinity of the pile and thus imply limitations of conventional design methods in which fully drained conditions were assumed. To shed light on this issue, a fully-coupled finite element model was established using an in-house developed finite element code DBLEAVES, incorporating a cyclic mobility constitutive model that is capable of describing the instantaneous contractive and dilative response of sands simultaneously. Triaxial and centrifuge model tests were conducted to calibrate the constitutive model and validate the pile–soil interaction model respectively. This is followed by a parametric study primarily focusing on the effects of loading rates. The initial stiffness of the p–y curve was found to increase with the loading rate whilst the bearing capacity showed the inverse,and the mechanism behind this phenomenon is examined in detail. Then an explicit model was developed to evaluate the development of excess pore pressure in the pile front upon lateral loading, and an upper boundary of normalized loading rate was identified to distinguish fully and partially drained conditions.展开更多
Vibration pore water pressure characteristics of saturated fine sand under partially drained condition were investigated through stress-controlled cyclic triaxial tests employed varied fine content of samples and load...Vibration pore water pressure characteristics of saturated fine sand under partially drained condition were investigated through stress-controlled cyclic triaxial tests employed varied fine content of samples and loading frequency. In order to simulate the partially drained condition, one-way drainage for sample was implemented when cyclic loading was applied. The results show that the vibration pore water pressure's response leads the axial stress and axial strain responses, and is lagged behind or simultaneous with axial strain-rate's response for all samples in this research. In addition, the satisfactory linear relationship between vibration pore water pressure amplitude and axial strain-rate amplitude is also obtained. It means that the direct cause of vibration pore water pressure generation under partially drained conditions is not the axial stress or axial strain but the axial strain-rate. The lag-phase between pore water pressure and axial strain-rate increases with the increase of the fine content or the loading frequency.展开更多
To investigate the influence of drainage conditions on stress relaxation characteristics of warm frozen soil, a series of laboratory tests were carried out under drained and undrained conditions. The results indicate ...To investigate the influence of drainage conditions on stress relaxation characteristics of warm frozen soil, a series of laboratory tests were carried out under drained and undrained conditions. The results indicate that confining pressure obviously influences the relaxation process of warm frozen soil. Under undrained condition, with increase in confining pressure, the critical relaxation du- ration tends to grow as well as instantaneous relaxation. But the relaxation rate is sensitive to confining pressure in the initial stage, and with further development, the effect tends to diminish. Under drained condition, the relaxation rate is greater than that under tmdrained condition in the initial stage but with the development of relaxation, the difference decreases. The volumetric defor- mation of warm frozen clay under drained condition is much larger than that under undrained condition.展开更多
Landslides frequently occurred in Jurassic red strata in the Three Gorges Reservoir(TGR)region in China.The Jurassic strata consist of low mechanical strength and poor permeability of weak silty mudstone layer,which m...Landslides frequently occurred in Jurassic red strata in the Three Gorges Reservoir(TGR)region in China.The Jurassic strata consist of low mechanical strength and poor permeability of weak silty mudstone layer,which may cause slope instability during rainfall.In order to understand the strength behavior of Jurassic silty mudstone shear zone,the so-called Shizibao landslide located in Guojiaba Town,Zigui County,Three Gorges Reservoir(TGR)in China is selected as a case study.The shear strength of the silty mudstone shear zone is strongly influenced by both the water content and the normal stress.Therefore,a series of drained ring shear tests were carried out by varying the water contents(7%,12%,17%,and 20%,respectively)and normal stresses(200,300,400,and 500 kPa,respectively).The result revealed that the residual friction coefficient and residual friction angle were power function relationships with water content and normal stress.The peak cohesion of the silty mudstone slip zone increased with water content to a certain limit,above which the cohesion decreased.In contrast,the residual cohesion showed the opposite trend,indicating the cohesion recovery above a certain limit of water content.However,both the peak and residual friction angle of the silty mudstone slip zone were observed to decrease steadily with increased water content.Furthermore,the macroscopic morphological features of the shear surface showed that the sliding failure was developed under high normal stress at low water content,while discontinuous sliding surface and soil extrusion were occurred when the water content increased to a saturated degree.The localized liquefaction developed by excess pore water pressure reduced the frictional force within the shear zone.Finally,the combined effects of the slope excavation and precipitation ultimately lead to the failure of the silty mudstone slope;however,continuous rainfall is the main factor triggering sliding.展开更多
The present study investigates the critical state behaviour of granular assemblies composed of clumped particles under four different drained axisymmetric triaxial stress paths,using the discrete element method(DEM).A...The present study investigates the critical state behaviour of granular assemblies composed of clumped particles under four different drained axisymmetric triaxial stress paths,using the discrete element method(DEM).A series of numerical samples were prepared at initial states with different density indexes(1D)and different initial confining pressures(ρ′0).These samples were sheared to large strains,at which constant stresses and volumes were maintained to reach the critical state.The evolution of stress ratio under the same loading mode(for the same intermediate principal stress ratio,b)is shown to yield an almost identical behaviour independent of stress paths,whereas the stress-strain response depends on the stress paths.Four different axisymmetric stress paths all share the same unique friction angle at critical state,indicating the Mohr-Coulomb failure criterion is the appropriate critical state strength criterion,which is at least true for the axisymmetric stress conditions.A unique coordination number(CN)is achieved at the critical state for a given po,which is independent of the stress path.The critical state CN is found to increase with the increase in po,which could be attributed to the decrease in the critical state void ratio(ec)as mean effective stress(ρ′0)increases.Interestingly,a unique linear functional relationship is found between the critical state values of cN and ec,and a unique polynomial functional relationship is found between the critical state values of CN andρ′.These functional relationships indicate no dependency on the stress paths or loading modes,thus characterizing unique features at critical states at both macroscopic and microscopic levels for a given type of granular material.展开更多
OBJECTIVE:To evaluate the 10-year therapeutic efficacy of Traditional Chinese Medicine(TCM)using the Strengthening Spleen and Draining Dampness therapy in the management of idiopathic membranous nephropathy(IMN).METHO...OBJECTIVE:To evaluate the 10-year therapeutic efficacy of Traditional Chinese Medicine(TCM)using the Strengthening Spleen and Draining Dampness therapy in the management of idiopathic membranous nephropathy(IMN).METHODS:A single-center,retrospective analysis was conducted on patients diagnosed with IMN who met predefined inclusion and exclusion criteria.Data were collected from the Department of Nephrology at Longhua Hospital,affiliated with Shanghai University of Traditional Chinese Medicine,between January 2007 and December 2011.Clinical parameters including 24-h urinary protein,serum albumin,serum creatinine,and estimated glomerular filtration rate(e GFR,EPI)were assessed at baseline and at 1,3,5,and 10 years of follow-up.The efficacy of the Strengthening Spleen and Draining Dampness therapy was analyzed using repeated measures analysis of variance(ANOVA).Kaplan-Meier survival curves and multivariate proportional hazards model(Cox regression models)were employed to identify factors associated with treatment outcomes.RESULTS:A total of 265 patients were included,with a median follow-up duration of 96 months(36,122).TCM treatment significantly reduced 24-h urinary protein levels(P<0.001),and increased serum albumin levels(P<0.001),while serum creatinine remained stable(P=0.187).Remission rates at 1,3,5,and 10 years were 52.81%,69.71%,68.39%,and 72.36%,respectively,and the rates of avoiding composite outcome events at the same intervals were 98.27%,94.29%,94.19%,and 93.50%.In the subgroup receiving TCM only,remission rates were 56.67%,84.44%,76.32%,and 82.86%.For patients treated initially with Western Medicine followed by TCM,the rates were 52.83%,65.85%,67.47%and 67.75%.In the cohort of patients who received TCM as their first-line therapy,remission rates were 49.23%,62.50%,61.76%,and 69.23%.Multivariate Cox regression analysis revealed that the duration of TCM treatment[hazard ratio(HR)=0.826,95%confidence interval(CI)(0.779,0.876),P<0.001],presence of hypertension[HR=1.912,95%CI(1.181,3.094),P=0.008],baseline serum albumin level[HR=0.930,95%CI(0.894,0.969),P<0.001],and the rate of serum albumin increase within the first year of treatment[HR=0.930,95%CI(0.909,0.957),P<0.001]were significantly associated with clinical outcomes.CONCLUSION:The Strengthening Spleen and Draining Dampness therapy demonstrated robust short-and longterm efficacy in treating IMN,with high rates of remission and renal survival over 10 years.Key factors influencing clinical remission included the duration of TCM treatment,baseline serum albumin levels,the presence of hypertension,and the rate of increase in serum albumin within the first year.These findings suggest that this TCM approach provides a viable long-term treatment option for IMN.展开更多
BACKGROUND Historically intraoperative drains were employed after pancreatic surgery but over the last decade,there has been debate over the routine usage of drains.AIM To assess the necessity of intra-abdominal drain...BACKGROUND Historically intraoperative drains were employed after pancreatic surgery but over the last decade,there has been debate over the routine usage of drains.AIM To assess the necessity of intra-abdominal drain placement,identify the most effective drain type,and determine the optimal timing for drain removal.METHODS A systematic review of electronic databases,including PubMed,MEDLINE,PubMed Central,and Google Scholar,was conducted using Medical Subject Headings and keywords until December 2023.From an initial pool of 1910 articles,48 were included after exclusion and screening.The primary outcomes analyzed were clinically relevant postoperative pancreatic fistula(CR-POPF),delayed gastric emptying(DGE),overall morbidity,and mortality.Subgroup analyses were performed for pancreaticoduodenectomy and distal pancreatectomy.RESULTS Routine use of drains is associated with a statistically significant increase in the risk of CR-POPF and DGE.Conversely,patients who did not have drains placed experienced a significant reduction in morbidity,readmission rates,and reoperations.No significant differences were observed between active and passive drain types.Early drain removal(<3 days)yielded favorable outcomes compared to delayed removal.CONCLUSION Analysis of randomized controlled trials and cohort studies did not demonstrate an advantage of routine drain placement following pancreatic resection,potentially contributing to increased morbidity and mortality.The decision to use drains should be left to the discretion of the operating surgeon.However,early drain removal can substantially reduce morbidity.展开更多
BACKGROUND Esophagojejunal anastomotic leakage(EJAL)is a severe complication following gastrectomy for gastric cancer,typically treated with drainage and nutritional support.We report a case of intraluminal drain migr...BACKGROUND Esophagojejunal anastomotic leakage(EJAL)is a severe complication following gastrectomy for gastric cancer,typically treated with drainage and nutritional support.We report a case of intraluminal drain migration near the esophagojejunal anastomosis(EJA),resulting in persistent drainage and mimicking EJAL after total gastrectomy.CASE SUMMARY A 64-year-old male underwent open total gastrectomy with Roux-en-Y reconstruction for gastric adenocarcinoma,with two silicone drains placed near the EJA.On postoperative day(POD)4,the patient developed signs of peritonitis and sepsis,necessitating surgical re-exploration abscess drainage,peritoneal lavage,and drain repositioning.A contrast swallow study on POD 18 revealed rapid filling of the abdominal drain without extraluminal contrast collection.Persistent drainage prompted an upper gastrointestinal endoscopy on POD 59,which revealed approximately 5 cm of the drain within the esophagus,with the perforation site located 2 cm distal to the intact EJA.The drain was repositioned under endoscopic guidance.A repeat contrast radiograph on POD 67 demonstrated no evidence of extraluminal contrast extravasation or filling of the abdominal drain.The patient was subsequently discharged without further incident.CONCLUSION Intraluminal drain migration is a rare complication following gastric surgery but should be considered when persistent drainage occurs.展开更多
With the rapid development of information technology,the demand for high-performance and low-power microprocessors continues to grow.Traditional silicon-based semiconductor technologies have encountered numerous bottl...With the rapid development of information technology,the demand for high-performance and low-power microprocessors continues to grow.Traditional silicon-based semiconductor technologies have encountered numerous bottlenecks in performance enhancement,such as drain-induced barrier lowering,reduced mobility caused by interface scattering,and limited current on/off ratios.展开更多
Dear Editor,We introduce a novel surgical instrument designed to overcome the challenges in draining fluid from the suprachoroidal space in patients with choroidal detachment.In the evolving landscape of ophthalmic su...Dear Editor,We introduce a novel surgical instrument designed to overcome the challenges in draining fluid from the suprachoroidal space in patients with choroidal detachment.In the evolving landscape of ophthalmic surgeries,procedures that were once considered complex,such as those for choroidal detachment,are becoming increasingly common.Drainage of subchoroidal fluid was derived from 1985[1]with indirect visualization during scleral buckle surgery[2-4].展开更多
基金funding support from the National Key Research and Development Program of China(Grant No.2023YFB2604004)the National Natural Science Foundation of China(Grant No.52108374)the“Taishan”Scholar Program of Shandong Province,China(Grant No.tsqn201909016)。
文摘The expansion of a thick-walled hollow cylinder in soil is of non-self-similar nature that the stress/deformation paths are not the same for different soil material points.As a result,this problem cannot be solved by the common self-similar-based similarity techniques.This paper proposes a novel,exact solution for rigorous drained expansion analysis of a hollow cylinder of critical state soils.Considering stress-dependent elastic moduli of soils,new analytical stress and displacement solutions for the nonself-similar problem are developed taking the small strain assumption in the elastic zone.In the plastic zone,the cavity expansion response is formulated into a set of first-order partial differential equations(PDEs)with the combination use of Eulerian and Lagrangian descriptions,and a novel solution algorithm is developed to efficiently solve this complex boundary value problem.The solution is presented in a general form and thus can be useful for a wide range of soils.With the new solution,the non-self-similar nature induced by the finite outer boundary is clearly demonstrated and highlighted,which is found to be greatly different to the behaviour of cavity expansion in infinite soil mass.The present solution may serve as a benchmark for verifying the performance of advanced numerical techniques with critical state soil models and be used to capture the finite boundary effect for pressuremeter tests in small-sized calibration chambers.
文摘The present study concerns the revalorization of drained water from aquaculture ponds rearing Clarias gariepinus on okra crops. The rearing was carried out at the farm of Gaston Berger University in 100 m2 ponds. In each pond, the individuals of C. garipinus with an average weight of 6 ± 0.3 g were stocked at a density of 11 per m2. The water temperature and pH were measured during the experiment. The control fishing is carried out every month to monitor variations in the weight and size of reared individuals. The plant production is carried out in elementary plots measuring 3 m × 1.5 m. Each plot was fertilized with either: drained water from C. gariepinus rearing (DWC), poultry droppings (PD), cow dung (CD) and mineral fertilizer (NPK). Treatments are carried out in tripliqua with either river water (RW), RW + the recommended dose of NPK (RD-NPK), RW + RD-PD, RW + RD-CD, DWC, DWC + 25% RD-NPK, DWC + 50% RD-NPK, DWC + 75% RD-NPK, DWC + 25% RD-PD, DWC + 50% RD-PD, DWC + 75% RD-PD, DWC + 25% RD-CD, DWC + 50% RD-CD, DWC + 75% RD-CD. Growth parameters and yield of okra were determined. The average temperature in the rearing environment was 27.6 ± 1.5˚C and pH 7.9 ± 1.1. After six (06) months of rearing, C. gariepinus individuals reached an average weight of 850.12 ± 1.3 g and an average height of 52.44 ± 1.1 cm. The daily weight gain and specific growth rates over this period were 3.9 g per day and 2.8% per day, respectively. The treatment T1 (RW + DR-NPK) gave the highest mean collar diameter and mean plant height with 2.3 ± 0.9 cm and 61.6 ± 32 cm, respectively. In T4 (DWC), the mean height of plants was 38.8 ± 23.5 cm and mean collar diameter 1.4 ± 0.8 cm. The growth performance in T4 was comparable to that of RD-CD (T3), but different from RD-NPK (T1) and RD-PD (T2). The highest average number, average weight, average length and average diameter of fruits were noted in treatments T13 (RW + RD-75%CD) and T7 (DWC + 75% RD-NPK). The best yields were noted in T1 (RW + RD-NPK) = 10.8 ± 5.4 t·ha−1, T5 (DWC + 25% RD-NPK) = 9.2 ± 4.6 t·ha−1 and T4 (DWC) = 8.6 ± 4.3 t·ha−1 which are comparable and higher than those obtained in T2 = 5.7 ± 2.8 t·ha−1 and T3 = 7.5 ± 3.8 t·ha−1.
基金funded by the Engineering and Physical Sciences Research Council, UK (Grant No.GR/R91588)
文摘Three dimensional （3D） DEM （discrete element method） simulations of drained triaxial compression and plane strain tests are presented for both dense and loose assemblies of polydisperse spheres using a periodic cell. In the work reported, drained tests were modelled by deforming the samples under constant mean stress conditions. The drained behaviour is shown to be qualitatively similar to published physical experimental results. The Bishop＇s formula for the estimation of the intermediate principal stress is evaluated. The existence of critical density is shown to be independent of initial packing densities and strain conditions. Different failure criteria have been compared based on the DEM simulation results, and the Lade criterion is found to be the most appropriate one. A new microscopic fabric parameter is introduced to give insight to structural anisotropy under general 3D fabric conditions. It is found that two parameters characterize the evolution of the stress and fabric respectively independent of strain conditions.
基金supported by the National Key Fundamental Research&Development Project of China(No.G1999064903).
文摘A 2D full cell thermo-electric model of 160kA drained cell was set up using finiteelement code to calculate its freeze profile, then the drained cell model was modifiedaccording to the freeze profile computed and its heat balance was calculated. Comparedwith that of a 160kA conventional Hall-Heroult cell (H-H cell), though the melts vol-ume of the drained cell reduced greatly, the whole heat loss from it didn't drop downapparently, and an analysis was presented in the paper. On the other hand, the anode-cathode distance (ACD) of a drained cell was much less than that of a H-H cell, sothe voltage drop on it and heat produced decreased too, steps should be taken to keepa workable heat balance on a drained cell.
基金Project(G1999064903) supported by the National Key Fundamental Research and Development Program of China
文摘Based on the commercial CFD software CFX-4.3, two-phase flow of electrolyte in 156 kA drained aluminum reduction cells with a new structure was numerically simulated by multi-fluid model and k-ε turbulence model. The results show that the electrolyte flow in the drained cells is more even than in the conventional cells. Corresponding to center point feeding, the electrolyte flow in the drained cells is more advantageous to the release of anode gas, the dissolution and diffusion of alumina, and the gradient reduction of the electrolyte density and temperature. The average velocity of the electrolyte is 8.3 cm/s, and the maximum velocity is 59.5 cm/s. The average and maximum velocities of the gas are 23.2 cm/s and 61.1 cm/s, respectively. The cathode drained slope and anode cathode distance have certain effects on the electrolyte flow.
文摘The drainage areas(and volumes)near hydraulically fractured wells,computed and visualized in our study at high resolution,may be critically affected by the presence of natural fractures.Using a recently developed algorithm based on complex analysis methods(CAMs),the drained rock volume(DRV)is visualized for a range of synthetic constellations of natural fractures near hydraulic fractures.First,flow interference effects near a single hydraulic fracture are systematically investigated for a variety of natural fracture sets.The permeability contrast between the matrix and the natural fractures is increased stepwise in order to better understand the effect on the DRV.Next,a larger-scale model investigates flow interference for a full hydraulically fractured well with a variety of natural fracture sets.The time of flight contours(TOFCs)outlining the DRV are for all cases with natural fractures compared to a base case without any natural fractures.Discrete natural fractures,with different orientations,hydraulic conductivity,and fracture density,may shift the TOFC patterns in the reservoir region drained by the hydraulically fractured well,essentially shifting the location of the well’s drainage area.The CAM-based models provide a computationally efficient method to quantify and visualize the drainage in both naturally and hydraulically fractured reservoirs.
基金Projects(50374081 60634020) supported by the National Natural Science Foundation of China
文摘Based on the principle of energy conservation,the applicable technique for drained cell retrofitted from conventional one was analyzed with 2D finite element model. The model employed a 1D heat transfer scheme to compute iteratively the freeze profile until the thickness variable reached the terminating requirement. The calculated 2D heat dissipation from the cell surfaces was converted into the overall 3D heat loss. The potential drop of the system, freeze profile and heat balance were analyzed to evaluate their variation with technical parameters when designing the 150 kA conventional cell based drained cell. The simulation results show that the retrofitted drained cell is able to keep thermal balance under the conditions that the current is 190 kA, the anodic current density is 0.96 A/cm2, the anode-cathode distance is 2.5 cm, the alumina cover is 16 cm thick with a thermal conductivity of 0.20 W/(m·℃ ) and the electrolysis temperature is 946 ℃ .
基金Project(2005CB623703) supported by the National Basic Research Program of China
文摘Current distribution in a drained aluminum reduction cell is critical due to its influence on the current efficiency, electrolysis stability, anodes and cathodes integrity. A finite element model was developed to simulate the electric field in a 75 kA drained aluminum reduction cell. The current distribution and influences of the cathode inclination angle and anode-cathode distance (ACD) were studied. The results show that relatively large horizontal current density appears in the aluminum film, and the maximum value reaches 600 kA/m2. As the cathode inclination angle increases from 2° to 15°, the maximum current density of the metal pad increases by 15%, while the maximum current density of the aluminum-wettable coating layer decreases by 27%. The influence of the ACD on the current distribution is not obvious.
文摘Based on principles of electromagnetic fluid dynamics the exerted forces and movement states of melted aluminum in the traditional reduction cells and the drained cells were compared and analyzed in this paper. And based on the theory of slow movement, a formula in respect of the drained angle was derived, i.e. θ≥(J zB x-J xB z)ρg-(J xB y-J yB x ). It can be seen that the drained slope can be decided by respectively multiplying the area current densities and magnetic induction intensities in three coordinate directions in aluminum reduction cells, and the drained slope is approximate to 0.6% derived from typical data based on measurement and calculation, which implies that the key parameter is obtained in designing of drained cells. The results can be used for a designing basis for drained cathodes.
文摘This study applies the Lindenmayer system based on fractal theory to generate synthetic fracture networks in hydraulically fractured wells.The applied flow model is based on complex analysis methods,which can quantify the flow near the fractures,and being gridless,is computationally faster than traditional discrete volume simulations.The representation of hydraulic fractures as fractals is a more realistic representation than planar bi-wing fractures used in most reservoir models.Fluid withdrawal from the reservoir with evenly spaced hydraulic fractures may leave dead zones between planar fractures.Complex fractal networks will drain the reservoir matrix more effectively,due to the mitigation of stagnation flow zones.The flow velocities,pressure response,and drained rock volume(DRV)are visualized for a variety of fractal fracture networks in a single-fracture treatment stage.The major advancement of this study is the improved representation of hydraulic fractures as complex fractals rather than restricting to planar fracture geometries.Our models indicate that when the complexity of hydraulic fracture networks increases,this will suppress the occurrence of dead flow zones.In order to increase the DRV and improve ultimate recovery,our flow models suggest that fracture treatment programs must find ways to create more complex fracture networks.
基金financially supported by the National Natural Science Foundation of China (Grant Nos. 51988101 and 51679211)。
文摘Reliable assessment of the lateral pile–soil interaction is of pronounced importance for the design of mono-pile foundations of offshore wind turbines. As the offshore engineering moves to deeper waters, the diameter of monopiles is getting larger, usually about 5 m and could be up to 8 m, which may lead to partially drained behaviors of sand in the vicinity of the pile and thus imply limitations of conventional design methods in which fully drained conditions were assumed. To shed light on this issue, a fully-coupled finite element model was established using an in-house developed finite element code DBLEAVES, incorporating a cyclic mobility constitutive model that is capable of describing the instantaneous contractive and dilative response of sands simultaneously. Triaxial and centrifuge model tests were conducted to calibrate the constitutive model and validate the pile–soil interaction model respectively. This is followed by a parametric study primarily focusing on the effects of loading rates. The initial stiffness of the p–y curve was found to increase with the loading rate whilst the bearing capacity showed the inverse,and the mechanism behind this phenomenon is examined in detail. Then an explicit model was developed to evaluate the development of excess pore pressure in the pile front upon lateral loading, and an upper boundary of normalized loading rate was identified to distinguish fully and partially drained conditions.
基金Project(2007CB714200) supported by National Basic Research Development Program of ChinaProject(90715018) supported by the National Natural Science Foundation of China (Key Program)
文摘Vibration pore water pressure characteristics of saturated fine sand under partially drained condition were investigated through stress-controlled cyclic triaxial tests employed varied fine content of samples and loading frequency. In order to simulate the partially drained condition, one-way drainage for sample was implemented when cyclic loading was applied. The results show that the vibration pore water pressure's response leads the axial stress and axial strain responses, and is lagged behind or simultaneous with axial strain-rate's response for all samples in this research. In addition, the satisfactory linear relationship between vibration pore water pressure amplitude and axial strain-rate amplitude is also obtained. It means that the direct cause of vibration pore water pressure generation under partially drained conditions is not the axial stress or axial strain but the axial strain-rate. The lag-phase between pore water pressure and axial strain-rate increases with the increase of the fine content or the loading frequency.
基金supported in part by the National Natural Science Foundation of China (No. 40871039)the 100 Young Talents Project granted to Dr.JiLin Qi
文摘To investigate the influence of drainage conditions on stress relaxation characteristics of warm frozen soil, a series of laboratory tests were carried out under drained and undrained conditions. The results indicate that confining pressure obviously influences the relaxation process of warm frozen soil. Under undrained condition, with increase in confining pressure, the critical relaxation du- ration tends to grow as well as instantaneous relaxation. But the relaxation rate is sensitive to confining pressure in the initial stage, and with further development, the effect tends to diminish. Under drained condition, the relaxation rate is greater than that under tmdrained condition in the initial stage but with the development of relaxation, the difference decreases. The volumetric defor- mation of warm frozen clay under drained condition is much larger than that under undrained condition.
基金funded by the National Science Foundation of China(CN)(Nos.42090054,41922055,41931295)the Key Research and Development Program of Hubei Province of China(No.2020BCB079)。
文摘Landslides frequently occurred in Jurassic red strata in the Three Gorges Reservoir(TGR)region in China.The Jurassic strata consist of low mechanical strength and poor permeability of weak silty mudstone layer,which may cause slope instability during rainfall.In order to understand the strength behavior of Jurassic silty mudstone shear zone,the so-called Shizibao landslide located in Guojiaba Town,Zigui County,Three Gorges Reservoir(TGR)in China is selected as a case study.The shear strength of the silty mudstone shear zone is strongly influenced by both the water content and the normal stress.Therefore,a series of drained ring shear tests were carried out by varying the water contents(7%,12%,17%,and 20%,respectively)and normal stresses(200,300,400,and 500 kPa,respectively).The result revealed that the residual friction coefficient and residual friction angle were power function relationships with water content and normal stress.The peak cohesion of the silty mudstone slip zone increased with water content to a certain limit,above which the cohesion decreased.In contrast,the residual cohesion showed the opposite trend,indicating the cohesion recovery above a certain limit of water content.However,both the peak and residual friction angle of the silty mudstone slip zone were observed to decrease steadily with increased water content.Furthermore,the macroscopic morphological features of the shear surface showed that the sliding failure was developed under high normal stress at low water content,while discontinuous sliding surface and soil extrusion were occurred when the water content increased to a saturated degree.The localized liquefaction developed by excess pore water pressure reduced the frictional force within the shear zone.Finally,the combined effects of the slope excavation and precipitation ultimately lead to the failure of the silty mudstone slope;however,continuous rainfall is the main factor triggering sliding.
基金The financial support from Xi'an Jiaotong-Liverpool University(grant Nos.RDF 18-01-23,PGRS1906002 and REF-20-01-01)is gratefully acknowledged。
文摘The present study investigates the critical state behaviour of granular assemblies composed of clumped particles under four different drained axisymmetric triaxial stress paths,using the discrete element method(DEM).A series of numerical samples were prepared at initial states with different density indexes(1D)and different initial confining pressures(ρ′0).These samples were sheared to large strains,at which constant stresses and volumes were maintained to reach the critical state.The evolution of stress ratio under the same loading mode(for the same intermediate principal stress ratio,b)is shown to yield an almost identical behaviour independent of stress paths,whereas the stress-strain response depends on the stress paths.Four different axisymmetric stress paths all share the same unique friction angle at critical state,indicating the Mohr-Coulomb failure criterion is the appropriate critical state strength criterion,which is at least true for the axisymmetric stress conditions.A unique coordination number(CN)is achieved at the critical state for a given po,which is independent of the stress path.The critical state CN is found to increase with the increase in po,which could be attributed to the decrease in the critical state void ratio(ec)as mean effective stress(ρ′0)increases.Interestingly,a unique linear functional relationship is found between the critical state values of cN and ec,and a unique polynomial functional relationship is found between the critical state values of CN andρ′.These functional relationships indicate no dependency on the stress paths or loading modes,thus characterizing unique features at critical states at both macroscopic and microscopic levels for a given type of granular material.
基金Supported by the National Key Research and Development Project,Clinical Study on the Treatment of Refractory Membranous Nephropathy with the Treatment of Strengthening Spleen and Draining Dampness in Method using Single Group Target Value Method(No.2019YFC1709403)Systematic Study on the Diagnosis and Treatment Rules of Membranous Nephropathy in Traditional Chinese Medicine(No.2023YFC35033501,No.2023YFC35033503)。
文摘OBJECTIVE:To evaluate the 10-year therapeutic efficacy of Traditional Chinese Medicine(TCM)using the Strengthening Spleen and Draining Dampness therapy in the management of idiopathic membranous nephropathy(IMN).METHODS:A single-center,retrospective analysis was conducted on patients diagnosed with IMN who met predefined inclusion and exclusion criteria.Data were collected from the Department of Nephrology at Longhua Hospital,affiliated with Shanghai University of Traditional Chinese Medicine,between January 2007 and December 2011.Clinical parameters including 24-h urinary protein,serum albumin,serum creatinine,and estimated glomerular filtration rate(e GFR,EPI)were assessed at baseline and at 1,3,5,and 10 years of follow-up.The efficacy of the Strengthening Spleen and Draining Dampness therapy was analyzed using repeated measures analysis of variance(ANOVA).Kaplan-Meier survival curves and multivariate proportional hazards model(Cox regression models)were employed to identify factors associated with treatment outcomes.RESULTS:A total of 265 patients were included,with a median follow-up duration of 96 months(36,122).TCM treatment significantly reduced 24-h urinary protein levels(P<0.001),and increased serum albumin levels(P<0.001),while serum creatinine remained stable(P=0.187).Remission rates at 1,3,5,and 10 years were 52.81%,69.71%,68.39%,and 72.36%,respectively,and the rates of avoiding composite outcome events at the same intervals were 98.27%,94.29%,94.19%,and 93.50%.In the subgroup receiving TCM only,remission rates were 56.67%,84.44%,76.32%,and 82.86%.For patients treated initially with Western Medicine followed by TCM,the rates were 52.83%,65.85%,67.47%and 67.75%.In the cohort of patients who received TCM as their first-line therapy,remission rates were 49.23%,62.50%,61.76%,and 69.23%.Multivariate Cox regression analysis revealed that the duration of TCM treatment[hazard ratio(HR)=0.826,95%confidence interval(CI)(0.779,0.876),P<0.001],presence of hypertension[HR=1.912,95%CI(1.181,3.094),P=0.008],baseline serum albumin level[HR=0.930,95%CI(0.894,0.969),P<0.001],and the rate of serum albumin increase within the first year of treatment[HR=0.930,95%CI(0.909,0.957),P<0.001]were significantly associated with clinical outcomes.CONCLUSION:The Strengthening Spleen and Draining Dampness therapy demonstrated robust short-and longterm efficacy in treating IMN,with high rates of remission and renal survival over 10 years.Key factors influencing clinical remission included the duration of TCM treatment,baseline serum albumin levels,the presence of hypertension,and the rate of increase in serum albumin within the first year.These findings suggest that this TCM approach provides a viable long-term treatment option for IMN.
文摘BACKGROUND Historically intraoperative drains were employed after pancreatic surgery but over the last decade,there has been debate over the routine usage of drains.AIM To assess the necessity of intra-abdominal drain placement,identify the most effective drain type,and determine the optimal timing for drain removal.METHODS A systematic review of electronic databases,including PubMed,MEDLINE,PubMed Central,and Google Scholar,was conducted using Medical Subject Headings and keywords until December 2023.From an initial pool of 1910 articles,48 were included after exclusion and screening.The primary outcomes analyzed were clinically relevant postoperative pancreatic fistula(CR-POPF),delayed gastric emptying(DGE),overall morbidity,and mortality.Subgroup analyses were performed for pancreaticoduodenectomy and distal pancreatectomy.RESULTS Routine use of drains is associated with a statistically significant increase in the risk of CR-POPF and DGE.Conversely,patients who did not have drains placed experienced a significant reduction in morbidity,readmission rates,and reoperations.No significant differences were observed between active and passive drain types.Early drain removal(<3 days)yielded favorable outcomes compared to delayed removal.CONCLUSION Analysis of randomized controlled trials and cohort studies did not demonstrate an advantage of routine drain placement following pancreatic resection,potentially contributing to increased morbidity and mortality.The decision to use drains should be left to the discretion of the operating surgeon.However,early drain removal can substantially reduce morbidity.
文摘BACKGROUND Esophagojejunal anastomotic leakage(EJAL)is a severe complication following gastrectomy for gastric cancer,typically treated with drainage and nutritional support.We report a case of intraluminal drain migration near the esophagojejunal anastomosis(EJA),resulting in persistent drainage and mimicking EJAL after total gastrectomy.CASE SUMMARY A 64-year-old male underwent open total gastrectomy with Roux-en-Y reconstruction for gastric adenocarcinoma,with two silicone drains placed near the EJA.On postoperative day(POD)4,the patient developed signs of peritonitis and sepsis,necessitating surgical re-exploration abscess drainage,peritoneal lavage,and drain repositioning.A contrast swallow study on POD 18 revealed rapid filling of the abdominal drain without extraluminal contrast collection.Persistent drainage prompted an upper gastrointestinal endoscopy on POD 59,which revealed approximately 5 cm of the drain within the esophagus,with the perforation site located 2 cm distal to the intact EJA.The drain was repositioned under endoscopic guidance.A repeat contrast radiograph on POD 67 demonstrated no evidence of extraluminal contrast extravasation or filling of the abdominal drain.The patient was subsequently discharged without further incident.CONCLUSION Intraluminal drain migration is a rare complication following gastric surgery but should be considered when persistent drainage occurs.
文摘With the rapid development of information technology,the demand for high-performance and low-power microprocessors continues to grow.Traditional silicon-based semiconductor technologies have encountered numerous bottlenecks in performance enhancement,such as drain-induced barrier lowering,reduced mobility caused by interface scattering,and limited current on/off ratios.
基金Supported by Science and Technology Foundation of Tianjin Eye Hospital(No.YKPY2207)Tianjin Key Medical Discipline(Specialty)Construction Project(No.TJYXZDXK-016A).
文摘Dear Editor,We introduce a novel surgical instrument designed to overcome the challenges in draining fluid from the suprachoroidal space in patients with choroidal detachment.In the evolving landscape of ophthalmic surgeries,procedures that were once considered complex,such as those for choroidal detachment,are becoming increasingly common.Drainage of subchoroidal fluid was derived from 1985[1]with indirect visualization during scleral buckle surgery[2-4].
