Objective:To compare the effects of a pain management program and routine suctioning methods on the level of pain presence and agitation in Chinese adults admitted to the intensive care unit.To disseminate the results...Objective:To compare the effects of a pain management program and routine suctioning methods on the level of pain presence and agitation in Chinese adults admitted to the intensive care unit.To disseminate the results from the implementation of the evidence-informed pain management interventions for reducing pain presence and agitation during endotracheal tube suctioning(ETS)and translate the key finding to clinical nursing practice.Methods:A quasi-experimental study of a two-group post-test design was conducted in adults admitted after surgery to a surgical intensive care unit(SICU)of the Second Affiliated Hospital of Kunming Medical University,Yunnan,China in 2018.Fifty-two adults who met the study eligibility were included after consent,26 in each group.Patients in the control group received usual care while patients in the intervention group received interventions to reduce agitation and pain-related ETS.The impacts of the intervention on the level of pain presence and agitation were measured at 5 measuring time points using the Chinese versions of Critical-Care Pain Observation Tool(CPOT)and Richmond Agitation Sedation Scale(RASS).Results:The level of pain presence in the intervention group statistically significantly decreased during,immediately after,and 5 min after suctioning.The level of agitation in the intervention group significantly decreased during and immediately after suctioning.Conclusions:The findings provide support for the positive pain-relieving effects of the evidence-informed pain-related ETS management interventions when compared with the usual ETS practice.The study interventions were sufficiently effective and safe to maintain patent airway clean and patent as standardized suctioning and helps pain relief.So,evidence-based pain-related ETS management intervention is worthy of recommending to utilize in SICU patients as well as other patients who required suctioning.It is worth noting that integrating pre-emptive analgesia prescription and administration with non-pharmacological intervention plays a critical role in achieving pain relief.展开更多
With the development of critical care medicine,mechanical ventilation is extensively used in the Intensive Care Units (ICUs).Patients receiving invasive mechanical ventilation require sputum suctioning either regularl...With the development of critical care medicine,mechanical ventilation is extensively used in the Intensive Care Units (ICUs).Patients receiving invasive mechanical ventilation require sputum suctioning either regularly or as required to clear secretions from the airway and maintain airway patency.Accordingly,the requirement to disconnect the breathing loop tube for sputum suctioning is determined by the use of open or closed modes ofsuctioning.At present,the open suctioning system is most commonly used for clearing airway secretions.Since resistance to bacterial strains is rapidly increasing,the possibility of open suctioning in contaminating the ICU environment is often questioned,which was investigated in this study.展开更多
In this paper,we present a modeling of the soil-water characteristic curve for residual and sedimentary soils of Bom Brinquedo Hill’s,located in Antonina,Brazil.This mountain range region is characterized as a natura...In this paper,we present a modeling of the soil-water characteristic curve for residual and sedimentary soils of Bom Brinquedo Hill’s,located in Antonina,Brazil.This mountain range region is characterized as a natural disaster risk area,requiring continuous research related to the stability of the area.To obtain the soil-water characteristic curve,undisturbed samples of residual and sedimentary soil were collected,followed by suction testing using the filter paper method.Considering the bimodal characteristic presented by the soil,LABFIT software was employed for curve fitting using the generic formulation“Harris+C”.The results of the tests indicated that the phenomenon of hysteresis had a greater influence in situations with higher suction levels.When comparing the residual moisture values of the macropores between residual soil and sedimentary soil,the former exhibited the lower value.This suggests that the residual soil has a coarser grain size and larger pores,which facilitates the release of water retained in the soil’s macropores.展开更多
Objective:We aimed to study the effect of flexible ureteroscopy(FURS)for renal stones using a flexible and navigable suction ureteral access sheath(FANS)on intraoperative radiation dose and time.Methods:This was a mul...Objective:We aimed to study the effect of flexible ureteroscopy(FURS)for renal stones using a flexible and navigable suction ureteral access sheath(FANS)on intraoperative radiation dose and time.Methods:This was a multicenter study of adults who underwent FURS with FANS.The correlation analysis was done to identify factors affecting radiation dose and time measured by the C-arm fluoroscopy intraoperatively.Results:We analyzed 110 patients,with a median age of 50 years.Of them,72%were pre-stented prior to the procedure.The median stone volume was 1503 mm3 and the median operative time was 39 min.The median radiation dose was 7.4 mSv and median radiation time was 0.6 min.Totally,91%of patients achieved stone-free status(Grade A or B)on the non-contrast CT scan within 30 days postoperatively.There were no cases of postoperative sepsis.Body mass index,stone volume,and total operation time were associated with a higher radiation dose.Procedures performed under general anesthesia had a lower radiation dose and time than those performed under spinal anesthesia.Disposable scopes were associated with higher radiation time than reusable scopes but not dose.A low-power holmium laser had longer radiation time than other laser sources,but only the thulium fiber laser was associated with a significantly lower radiation dose.Conclusion:Our study is the first to highlight the multitude of factors affecting radiation exposure in FURS with FANS.Although not a direct measure of surgeons'actual exposure,it has important implications for the As Low As Reasonably Achievable principle which is commonly used to minimize radiation exposure to patients and operating room staff.展开更多
Surface soil cracking in alpine meadows signifies the transition of degradation from quantitative accumulation to qualitative deterioration.Quantitative research remains insufficient regarding changes in the mechanica...Surface soil cracking in alpine meadows signifies the transition of degradation from quantitative accumulation to qualitative deterioration.Quantitative research remains insufficient regarding changes in the mechanical properties of degraded meadow soils and the mechanical thresholds for cracking initiation.This study explored the relationships between surface cracking and the physical properties,tensile strength,and matrix suction of root-soil composites in alpine meadow sites with different stages of degradation(undegraded(UD),lightly degraded(LD),moderately degraded(MD),and heavily degraded(HD))under different water gradients(high water content(HWC),medium water content(MWC),and low water content(LWC))corresponding to different drying durations at a constant temperature of 40.0°C.The Huangcheng Mongolian Township in Menyuan Hui Autonomous County,Qinghai Province,China was chosen as the study area.The results indicated that as the degradation degree of alpine meadow intensified,both water content of rootsoil composite and the fine grain content of soil decreased.In contrast,the root-soil mass ratio and root area ratio initially increased and then decreased with progressive degradation.Under a consistent water content,the tensile strength of root-soil composite followed a pattern of MD>HD>LD>UD.The peak displacement of tensile strength also decreased as the degradation degree of alpine meadow increased.Both the tensile strength and matrix suction of root-soil composite increased as root-soil water content decreased.A root-soil water content of 30.00%-40.00%was found to be the critical threshold for soil cracking in alpine meadows.Within this range,the matrix suction of root-soil composite ranged from 50.00 to 100.00 kPa,resulting in the formation of linear cracks in the surface soil.As the root-soil water content continued to decrease,liner cracks evolved into branch-like and polygonal patterns.The findings of this study provide essential data for improving the mechanical understanding of grassland cracking and its development process.展开更多
This study investigates the heat transfer and flow dynamics of a ternary hybrid nanofluid comprising alumina,copper,and silica/titania nanoparticles dispersed in water.The analysis considers the effects of suction,mag...This study investigates the heat transfer and flow dynamics of a ternary hybrid nanofluid comprising alumina,copper,and silica/titania nanoparticles dispersed in water.The analysis considers the effects of suction,magnetic field,and Joule heating over a permeable shrinking disk.Amathematicalmodel is developed and converted to a systemof differential equations using similarity transformation which then,solved numerically using the bvp4c solver in Matlab software.The study introduces a novel comparative analysis of alumina-copper-silica and alumina-coppertitania nanofluids,revealing distinct thermal conductivity behaviors and identifying critical suction values necessary for flow stabilization.Dual solutions are found within a specific range of parameters such that the minimum required suction values for flow stability,with S_(c)=1.2457 for alumina-copper-silica/water and S_(c)=1.2351 for alumina-coppertitania/water.The results indicate that increasing suction by 1%enhances the skin friction coefficient by up to 4.17%and improves heat transfer efficiency by approximately 1%,highlighting its crucial role in stabilizing the opposing flow induced by the shrinking disk.Additionally,the inclusion of 1%silica nanoparticles reduces both skin friction and heat transfer rate by approximately 0.28%and 0.85%,respectively,while 1%titania concentration increases skin friction by 3.02%but results in a slight heat transfer loss of up to 0.61%.These findings confirm the superior thermal performance of alumina-copper-titania/water,making it a promising candidate for enhanced cooling systems,energy-efficient heat exchangers,and industrial thermal management applications.展开更多
A simplified analytical approach is proposed for predicting the load-displacement behavior of single piles in unsaturated soils considering the contribution from the nonlinear shear strength and soil stiffness influen...A simplified analytical approach is proposed for predicting the load-displacement behavior of single piles in unsaturated soils considering the contribution from the nonlinear shear strength and soil stiffness influenced by matric suction.This approach includes a Modified Load Transfer Model(MLTM)that can predict the nonlinear relationships between the shear stress and pile-soil relative displacement along the pile shaft,and between the pile base resistance and base settlement.The proposed model is also extended for pile groups to incorporate the interaction effects between individual piles.The analytical approach is validated through a comparative analysis with the measurements from two single pile tests and one pile group test.In addition,a finite element analysis using 3D modeling is carried out to investigate the behavior of pile groups in various unsaturated conditions.This is accomplished with a user-defined subroutine that is written and implemented in ABAQUS to simulate the nonlinear mechanical behavior of unsaturated soils.The predictions derived from the proposed analytical and numerical methods compare well with the measurements of a published experimental study.The proposed methodologies have the potential to be applied in geotechnical engineering practice for the rational design of single piles and pile groups in unsaturated soils.展开更多
Maximizing the efficiency of thermal engineering equipment involves minimizing entropy generation,which arises from irreversible processes.This study examines thermal transport and entropy generation in viscous flow o...Maximizing the efficiency of thermal engineering equipment involves minimizing entropy generation,which arises from irreversible processes.This study examines thermal transport and entropy generation in viscous flow over a radially stretching disk,incorporating the effects of magnetohydrodynamics(MHD),viscous dissipation,Joule heating,and radiation.Similarity transformations are used to obtain dimensionless nonlinear ordinary differential equations(ODEs)from the governing coupled partial differential equations(PDEs).The converted equations are then solved by using the BVP4C solver in MATLAB.To validate the findings,the results are compared with previously published studies under fixed parameter conditions,demonstrating strong agreement.Various key parameters are analyzed graphically to assess their impact on velocity and temperature distributions.Additionally,Bejan number and entropy generation variations are presented for different physical parameters.The injection parameter(S<0)increases the heat transfer rate,while the suction parameter(S>0)reduces it,exhibiting similar effects on fluid velocity.The magnetic parameter(M)effectively decreases entropy generation within the range of approximately 0≤η≤0.6.Beyond this interval,its influence diminishes as entropy generation values converge,with similar trends observed for the Bejan number.Furthermore,increased thermal radiation intensity is identified as a critical factor in enhancing entropy generation and the Bejan number.展开更多
When tunnelling through low-permeability saturated ground,the pore pressure decreases in the vicinity of the cavity.In certain instances of deep tunnels crossing weak rocks,the pore pressure may even become negative.A...When tunnelling through low-permeability saturated ground,the pore pressure decreases in the vicinity of the cavity.In certain instances of deep tunnels crossing weak rocks,the pore pressure may even become negative.All existing analytical solutions for the undrained ground response curve(GRC)in the literature assume that the ground fully retains its saturation,in which case the development of negative pore pressures has a stabilising effect e it results in increased effective stresses,and thus shearing resistance,which in turn leads to reduced deformations and plastification.In practice,however,negative pore pressures can induce partial or complete ground desaturation,which may even invalidate the premise of undrained conditions and lead to considerably increased deformations and plastification.In such cases,existing solutions are unsafe for design.The present paper aims to address this shortcoming,by presenting a novel analytical solution for the undrained GRC which incorporates the effect of the excavation-induced desaturation.The solution is derived under the assumption that the ground desaturates completely and immediately under negative pore pressures,which provides the upper bound of deformations and plastification for cases of partial desaturation.The rock is considered to be a linear elastic,brittle-plastic material,obeying a non-associated Mohr-Coulomb(MC)yield criterion.Nevertheless,the solution is also applicable to perfectly plastic rocks via a simple modification of the input parameters.Although the solution is in general semi-analytical,simple closed-form expressions are obtained in the special case of non-dilatant rocks.These expressions are also applicable to rocks exhibiting limited dilatancy,which is usually the case.An application example,based on the planned deep geological repository for radioactive waste in Switzerland,demonstrates the significant practical value and usefulness of the novel solution and underscores its necessity in cases where existing solutions that disregard desaturation are rendered thoroughly unsafe for design.展开更多
This study explores the bioconvective behavior of a Reiner-Rivlin nanofluid,accounting for spatially varying thermal properties.The flow is considered over a porous,stretching surface with mass suction effects incorpo...This study explores the bioconvective behavior of a Reiner-Rivlin nanofluid,accounting for spatially varying thermal properties.The flow is considered over a porous,stretching surface with mass suction effects incorporated into the transport analysis.The Reiner-Rivlin nanofluid model includes variable thermal conductivity,mass diffusivity,and motile microorganism density to accurately reflect realistic biological conditions.Radiative heat transfer and internal heat generation are considered in the thermal energy equation,while the Cattaneo-Christov theory is employed to model non-Fourier heat and mass fluxes.The governing equations are non-dimensionalized to reduce complexity,and a numerical solution is obtained using a shooting method.Parametric studies are conducted to examine the influence of key dimensionless parameters on velocity,temperature,concentration,and motile microorganism profiles.The results are presented through a series of graphs,offering insight into the dynamic interplay between physical mechanisms affecting heat and mass transfer in non-Newtonian bioconvective nanofluid systems.展开更多
The scaled suction caisson repre sents an innovative design featuring a bio-inspired sidewall modeled after snake skin,commonly utilized in offshore mooring platforms.In comparison with traditional suction caissons,th...The scaled suction caisson repre sents an innovative design featuring a bio-inspired sidewall modeled after snake skin,commonly utilized in offshore mooring platforms.In comparison with traditional suction caissons,this bio-inspired design demonstrates reduced penetration resistance and enhanced pull-out capacity due to the anisotropic shear behaviors of its sidewall.To investigate the shear behavior of the bio-inspired sidewall under pull-out load,direct shear tests were conducted between the bio-inspired surface and sand.The research demonstrates that the interface shear strength of the bio-inspired surface significantly surpasses that of the smooth surface due to interlocking effects.Additionally,the interface shear strength correlates with the aspect ratio of the bio-inspired surface,shear angle,and particle diameter distribution,with values increasing as the uniformity coefficient Cudecreases,while initially increasing and subsequently decreasing with increases in both aspect ratio and shear angle.The ratio between the interface friction angleδand internal friction angle δ_(s) defines the interface effect factor k.For the bio-inspired surface,the interface effect factor k varies with shear angleβ,ranging from 0.9 to 1.12.The peak value occurs at a shear angleβof 60°,substantially exceeding that of the smooth surface.A method for calculating the relative roughness R_(N) is employed to evaluate the interface roughness of the bio-inspired surface,taking into account scale dimension and particle diameter distribution effects.展开更多
Characteristics of heat transfer and flow of Newtonian and non-Newtonian fluids through porous walls and in porous media are studied due to their wide range of applications including geothermal reservoirs,heat exchang...Characteristics of heat transfer and flow of Newtonian and non-Newtonian fluids through porous walls and in porous media are studied due to their wide range of applications including geothermal reservoirs,heat exchangers,marine propulsion,and aerodynamics.The current study investigates the characteristics of heat transport in a reactive third-grade fluid,moving through permeable parallel plates,with uniform suction/injection velocity.The two permeable,parallel plates are maintained at the same,constant temperature.After being transformed into its dimensionless equivalent,governing equations are solved by employing the Least Squares Method(LSM).The LSM results are further validated with numerical solutions for temperature and velocity.The impact of cross-flow Reynolds number,Peclet number,heat generation parameter,non-Newtonian parameter,and Brinkman number on entropy generation,velocity,temperature,and Bejan number are investigated.Theresults indicate that temperature distribution is significantly influenced by the third-grade fluid parameter.The maximum temperature drops from almost 0.12 to 0.10 as the third-grade fluid parameter increases from0.05 to 0.4.When the cross-flow Reynolds number is raised from 0.05 to 3,the maximum temperature drops from 0.12 to around 0.09.Temperature is strongly influenced by the heat generation parameter.A greater understanding of the thermal characteristics necessary for the design of a variety of systems,such as heat exchangers,marine propulsion,aerodynamic systems,etc.,may be gained from the findings of the current study.展开更多
The complex behaviors of expansive soils,particularly their volumetric changes driven by moisture variations,pose significant challenges in urban geotechnical engineering.Although vegetation-induced moisture changes a...The complex behaviors of expansive soils,particularly their volumetric changes driven by moisture variations,pose significant challenges in urban geotechnical engineering.Although vegetation-induced moisture changes are known to affect ground movement,quantitative characterization of tree–soil interactions remains limited due to insufficient field data and unclear relationships between tree water uptake and soil response.This study investigates the mechanical behavior of expansive clay soils influenced by two Lophostemon confertus samples during a 14-month field monitoring program in Melbourne,Australia.The research methodology integrates measurements of soil displacement,total soil suction,moisture content,and tree water consumption through instrumentation and monitoring systems.Field measurements suggest that tree roots reached the limits of their water extraction capacity when total soil suction exceeded 2880 kPa within the active root zone.The spatial extent of tree-induced soil desiccation reached 0.6–0.7 times the tree height laterally and penetrated to depths of 2.5–3.3 m vertically.The mature sample,with an 86%greater crown area and a threefold larger sapwood area,exhibited 142%higher water consumption(35 kL),demonstrating the scalability of tree–soil interaction mechanisms.A multiple linear regression model was developed to quantify the coupled relationships between soil movement and key variables,achieving a high adjusted R2 value of 0.97,which provides engineers and practitioners with a practical tool for estimating ground movement near trees.These findings offer valuable insights for infrastructure design in tree-adjacent environments and can inform computational models and design codes to enable more accurate site assessments and sustainable urban development.展开更多
Experimental research into the hydraulic conductivity curve (HCC) of unsaturated soil is limited due to the inherent challenge associated with labor, cost, and time. Typically, the HCC is estimated using the soil wate...Experimental research into the hydraulic conductivity curve (HCC) of unsaturated soil is limited due to the inherent challenge associated with labor, cost, and time. Typically, the HCC is estimated using the soil water characteristic curve (SWCC) based models and saturated hydraulic conductivity (SHC). However, the efficiency of the SWCC-based model is rarely assessed, and the influence of soil density and pore structure on HCC remains incomplete due to limited experimental data. To address this gap, this study employs an innovative filter-paper-based column method, which can measure the HCC over a wide suction range (e.g. 0−105 kPa), to capture the HCCs of both intact and compacted specimens with varying dry densities. The efficiency of two typical SWCC-based models is assessed using the measured data. Meanwhile, the mercury intrusion porosity (MIP) technique is employed to obtain the pore characteristic (i.e. pore size distribution (PSD)) and a method of predicting the HCC using the PSD data is proposed, emphasizing the dominant role of the pore structure in shaping the HCC. The results reveal that the dry density's influence on the HCC is primarily observed within the low suction range, corresponding to variations in the dominant and large pores. In the high suction range, the HCCs align along a linear trajectory when plotted in a log-log format. A notable finding is the overestimation of the HCC obtained from the SWCC-based models using the measured SHC. When the SHC is regarded as a fitting parameter, good agreement is achieved. The adjusted SHC value is typically 0-1 order of magnitude lower than the measured value, and this discrepancy diminishes as dry density increases. On the other hand, the proposed PSD-based model performs well with the measured SHC data. Caution is exercised when using the SHC to estimate the HCC for modeling water movement in partially saturated soil.展开更多
Unsaturated soil mechanics is crucial in understanding ground conditions and constructing geotechnical structures,particularly amidst the challenges posed by global climate change.Nevertheless,acquiring accurate soil ...Unsaturated soil mechanics is crucial in understanding ground conditions and constructing geotechnical structures,particularly amidst the challenges posed by global climate change.Nevertheless,acquiring accurate soil suction values remains challenging due to limitations in existing methodologies,such as susceptibility to cavitation,high costs,and time-intensive procedures.Hence,this study employs a high-suction polymer sensor(HSPS)to evaluate the polymer's performance in determining soil suction.Subsequently,the polymers were used to measure unsaturated soil properties,especially soil-water characteristics curves(SWCC),based on osmotic principles.Five polymer samples classified as superabsorbent polymers(SAP)were synthesized with varying degrees of crosslinking,and their properties were assessed through swelling test and Fourier-transform infrared spectroscopy(FTIR).The soil sample from Turan,located within Nazarbayev University,was analyzed using a bimodal equation to determine the best fit.Results revealed that the swelling value and structural integrity of the polymer significantly affect soil suction capacity,with the findings being deemed temperature-independent,thereby obviating the need for calibration.Two potential factors hindering suction increase were identified:cavitation within the polymer or a reduction in the osmotic gradient due to polymer transformation into hydrogel formation.Overall,the novel polymer shows promise as an alternate material for SWCC measurement considering its simple method and being more sustainable compared to the other polymers,although further investigation is required to enhance the suction potential.展开更多
The design of high-lift Low-Pressure Turbines(LPTs)causes the separation of the boundary layer on the suction side of the blade and leads to a strong secondary flow.This present study aims to minimize secondary losses...The design of high-lift Low-Pressure Turbines(LPTs)causes the separation of the boundary layer on the suction side of the blade and leads to a strong secondary flow.This present study aims to minimize secondary losses through endwall slot suction and incoming wakes in a front-loaded high-lift LPT cascade with Zweifel of 1.58 under low Reynolds number of 25000.Two slotted schemes for the boundary layer of the endwall were designed(Plan A and Plan B),and the effects of suction mass flow on secondary flow were studied.The underlying physics of the endwall boundary layer of the suction and secondary flow under unsteady wakes was discussed.The results show that slot suction at the endwall boundary layer can significantly suppress the secondary flow by removing low-momentum fluids.Plans A and B significantly reduced the secondary kinetic energy by 44.2%and 36.9%,respectively,compared with the baseline cascade at the suction mass flow ratios of 1%.With an increase in the mass flow ratio of suction,the secondary flow was gradually reduced in both Plans A and B.It is more beneficial to control the secondary flow to destroy the intersection of the pressure side and suction side of the horseshoe vortex before it develops into a passage vortex.Under unsteady wakes,the combined effects of incoming wakes and endwall boundary layer suction can further suppress the secondary flow at the suction mass flow ratios of 2%for Plan A,because the positive and negative vorticity inside upstream wakes accelerated the mixing of the main flow and secondary flow and thus increased the energy of secondary vortices.展开更多
Earthquake-induced slope failures are common occurrences in engineering practice and pre-stressed anchor cables are an effective technique in maintaining slope stability,especially in areas that are prone to earthquak...Earthquake-induced slope failures are common occurrences in engineering practice and pre-stressed anchor cables are an effective technique in maintaining slope stability,especially in areas that are prone to earthquakes.Furthermore,the soil at typical engineering sites also exhibit unsaturated features.Explicit considerations of these factors in slope stability estimations are crucial in producing accurate results.In this study,the seismic responses of expansive soil slopes stabilized by anchor cables is studied in the realm of kinematic limit analysis.A modified horizontal slice method is proposed to semi-analytically formulate the energy balance equation.An illustrative slope is studied to demonstrate the influences of suction,seismic excitations and anchor cables on the slope stability.The results indicate that the stabilizing effect of soil suction relates strongly to the seismic excitation and presents a sine shape as the seismic wave propagates.In higher and steeper slopes,the stabilizing effect of suction is more evident.The critical slip surface tends to be much more shallow as the seismic wave approaches the peak and vice versa.展开更多
The tripod foundation(TF)is a prevalent foundation configuration in contemporary engineering practices.In comparison to a single pile,TF comprised interconnected individual piles,resulting in enhanced bearing capacity...The tripod foundation(TF)is a prevalent foundation configuration in contemporary engineering practices.In comparison to a single pile,TF comprised interconnected individual piles,resulting in enhanced bearing capacity and stability.A physical model test was conducted within a sandy soil foundation,systematically varying the length-to-diameter ratio of the TF.The investigation aimed to comprehend the impact of altering the height of the central bucket on the historical horizontal bearing capacity of the foundation in saturated sand.Additionally,the study scrutinized the historical consequences of soil pressure and pore water pressure surrounding the bucket throughout the loading process.The historical findings revealed a significant enhancement in the horizontal bearing capacity of the TF under undrained conditions.When subjected to a historical horizontal loading angle of 0°for a single pile,the multi-bucket foundation exhibited superior historical bearing capacity compared to a single-pile foundation experiencing a historical loading angle of 180°under pulling conditions.With each historical increment in bucket height from 150 mm to 350 mm in 100 mm intervals,the historical horizontal bearing capacity of the TF exhibited an approximately 75%increase relative to the 150 mm bucket height,indicating a proportional relationship.Importantly,the historical internal pore water pressure within the bucket foundation remained unaffected by drainage conditions during loading.Conversely,undrained conditions led to a historical elevation in pore water pressure at the lower side of the pressure bucket.Consequently,in practical engineering applications,the optimization of the historical bearing efficacy of the TF necessitated the historical closure of the valve atop the foundation to sustain internal negative pressure within the bucket.This historical measure served to augment the historical horizontal bearing capacity.Simultaneously,historical external loads,such as wind,waves,and currents,were directed towards any individual bucket within the TF for optimal historical performance.展开更多
Purpose-The experiments of this study investigated the effect of the subgrade degree of saturation on the value of the stresses generated on the surface and the middle(vertical and lateral stresses).The objectives of ...Purpose-The experiments of this study investigated the effect of the subgrade degree of saturation on the value of the stresses generated on the surface and the middle(vertical and lateral stresses).The objectives of this study can be identified by studying the effect of subgrade layer degree of saturation variation,load amplitude and load frequency on the transmitted stresses through the ballast layer to the subgrade layer and the stress distribution inside it and investigating the excess pore water pressure development in the clay layer in the case of a fully saturated subgrade layer and the change in matric suction in the case of an unsaturated subgrade layer.Design/methodology/approach-Thirty-six laboratory experiments were conducted using approximately half-scale replicas of real railways,with an iron box measuring 1.5×1.031.0 m.Inside the box,a 0.5 m thick layer of clay soil representing the base layer was built.Above it is a 0.2 m thick ballast layer made of crushed stone,and on top of that is a 0.8 m long rail line supported by three 0.9 m(0.1×0.1 m)slipper beams.The subgrade layer has been built at the following various saturation levels:100,80,70 and 60%.Experiments were conducted with various frequencies of 1,2 and 4 Hz with load amplitudes of 15,25 and 35 kN.Findings-The results of the study demonstrated that as the subgrade degree of saturation decreased from 100 to 60%,the ratio of stress in the lateral direction to stress in the vertical direction generated in the middle of the subgrade layer decreased as well.On average,this ratio changed from approximately 0.75 to approximately 0.65.Originality/value-The study discovered that as the test proceeded and the number of cycles increased,the value of negative water pressure(matric suction)in the case of unsaturated subgrade soils declined.The frequency of loads had no bearing on the ratio of decline in matric suction values,which was greater under a larger load amplitude than a lower one.As the test progressed(as the number of cycles increased),the matric suction dropped.For larger load amplitudes,there is a greater shift in matric suction.The change in matric suction is greater at higher saturation levels than it is at lower saturation levels.Furthermore,it is seen that the load frequency value has no bearing on how the matric suction changes.For all load frequencies and subgrade layer saturation levels,the track panel settlement rises with the load amplitude.Higher load frequency and saturation levels have a greater impact.展开更多
We report on the magnetohydrodynamic impact on the axisymmetric flow of Al_(2)O_(3)/Cu nanoparticles suspended in H_(2)O past a stretched/shrinked sheet.With the use of partial differential equations and the correspon...We report on the magnetohydrodynamic impact on the axisymmetric flow of Al_(2)O_(3)/Cu nanoparticles suspended in H_(2)O past a stretched/shrinked sheet.With the use of partial differential equations and the corresponding thermophysical characteristics of nanoparticles,the physical flow process is illustrated.The resultant nonlinear system of partial differential equations is converted into a system of ordinary differential equations using the suitable similarity transformations.The transformed differential equations are solved analytically.Impacts of the magnetic parameter,solid volume fraction and stretching/shrinking parameter on momentum and temperature distribution have been analyzed and interpreted graphically.The skin friction and Nusselt number were also evaluated.In addition,existence of dual solution was deduced for the shrinking sheet and unique solution for the stretching one.Further,Al_(2)O_(3)/H_(2)O nanofluid flow has better thermal conductivity on comparing with Cu/H_(2)O nanofluid.Furthermore,it was found that the first solutions of the stream are stable and physically realizable,whereas those of the second ones are unstable.展开更多
基金Thailand’s Educations Hub for the Southern Region of ASEAN Countries (TEH-AC) Scholarship through Prince of Songkla University, Thailand, for a scholarship award to support this study
文摘Objective:To compare the effects of a pain management program and routine suctioning methods on the level of pain presence and agitation in Chinese adults admitted to the intensive care unit.To disseminate the results from the implementation of the evidence-informed pain management interventions for reducing pain presence and agitation during endotracheal tube suctioning(ETS)and translate the key finding to clinical nursing practice.Methods:A quasi-experimental study of a two-group post-test design was conducted in adults admitted after surgery to a surgical intensive care unit(SICU)of the Second Affiliated Hospital of Kunming Medical University,Yunnan,China in 2018.Fifty-two adults who met the study eligibility were included after consent,26 in each group.Patients in the control group received usual care while patients in the intervention group received interventions to reduce agitation and pain-related ETS.The impacts of the intervention on the level of pain presence and agitation were measured at 5 measuring time points using the Chinese versions of Critical-Care Pain Observation Tool(CPOT)and Richmond Agitation Sedation Scale(RASS).Results:The level of pain presence in the intervention group statistically significantly decreased during,immediately after,and 5 min after suctioning.The level of agitation in the intervention group significantly decreased during and immediately after suctioning.Conclusions:The findings provide support for the positive pain-relieving effects of the evidence-informed pain-related ETS management interventions when compared with the usual ETS practice.The study interventions were sufficiently effective and safe to maintain patent airway clean and patent as standardized suctioning and helps pain relief.So,evidence-based pain-related ETS management intervention is worthy of recommending to utilize in SICU patients as well as other patients who required suctioning.It is worth noting that integrating pre-emptive analgesia prescription and administration with non-pharmacological intervention plays a critical role in achieving pain relief.
基金This study was supported by grants from the Medical ScienceProgram of Zhejiang Province(No.2014KYB270)theEmergency Medicine Key Subject Fund Project of JiaxingCity in Zhejiang Province(No.04-F-06).
文摘With the development of critical care medicine,mechanical ventilation is extensively used in the Intensive Care Units (ICUs).Patients receiving invasive mechanical ventilation require sputum suctioning either regularly or as required to clear secretions from the airway and maintain airway patency.Accordingly,the requirement to disconnect the breathing loop tube for sputum suctioning is determined by the use of open or closed modes ofsuctioning.At present,the open suctioning system is most commonly used for clearing airway secretions.Since resistance to bacterial strains is rapidly increasing,the possibility of open suctioning in contaminating the ICU environment is often questioned,which was investigated in this study.
文摘In this paper,we present a modeling of the soil-water characteristic curve for residual and sedimentary soils of Bom Brinquedo Hill’s,located in Antonina,Brazil.This mountain range region is characterized as a natural disaster risk area,requiring continuous research related to the stability of the area.To obtain the soil-water characteristic curve,undisturbed samples of residual and sedimentary soil were collected,followed by suction testing using the filter paper method.Considering the bimodal characteristic presented by the soil,LABFIT software was employed for curve fitting using the generic formulation“Harris+C”.The results of the tests indicated that the phenomenon of hysteresis had a greater influence in situations with higher suction levels.When comparing the residual moisture values of the macropores between residual soil and sedimentary soil,the former exhibited the lower value.This suggests that the residual soil has a coarser grain size and larger pores,which facilitates the release of water retained in the soil’s macropores.
文摘Objective:We aimed to study the effect of flexible ureteroscopy(FURS)for renal stones using a flexible and navigable suction ureteral access sheath(FANS)on intraoperative radiation dose and time.Methods:This was a multicenter study of adults who underwent FURS with FANS.The correlation analysis was done to identify factors affecting radiation dose and time measured by the C-arm fluoroscopy intraoperatively.Results:We analyzed 110 patients,with a median age of 50 years.Of them,72%were pre-stented prior to the procedure.The median stone volume was 1503 mm3 and the median operative time was 39 min.The median radiation dose was 7.4 mSv and median radiation time was 0.6 min.Totally,91%of patients achieved stone-free status(Grade A or B)on the non-contrast CT scan within 30 days postoperatively.There were no cases of postoperative sepsis.Body mass index,stone volume,and total operation time were associated with a higher radiation dose.Procedures performed under general anesthesia had a lower radiation dose and time than those performed under spinal anesthesia.Disposable scopes were associated with higher radiation time than reusable scopes but not dose.A low-power holmium laser had longer radiation time than other laser sources,but only the thulium fiber laser was associated with a significantly lower radiation dose.Conclusion:Our study is the first to highlight the multitude of factors affecting radiation exposure in FURS with FANS.Although not a direct measure of surgeons'actual exposure,it has important implications for the As Low As Reasonably Achievable principle which is commonly used to minimize radiation exposure to patients and operating room staff.
基金funded by the National Natural Science Foundation of China(42062019,42002283)。
文摘Surface soil cracking in alpine meadows signifies the transition of degradation from quantitative accumulation to qualitative deterioration.Quantitative research remains insufficient regarding changes in the mechanical properties of degraded meadow soils and the mechanical thresholds for cracking initiation.This study explored the relationships between surface cracking and the physical properties,tensile strength,and matrix suction of root-soil composites in alpine meadow sites with different stages of degradation(undegraded(UD),lightly degraded(LD),moderately degraded(MD),and heavily degraded(HD))under different water gradients(high water content(HWC),medium water content(MWC),and low water content(LWC))corresponding to different drying durations at a constant temperature of 40.0°C.The Huangcheng Mongolian Township in Menyuan Hui Autonomous County,Qinghai Province,China was chosen as the study area.The results indicated that as the degradation degree of alpine meadow intensified,both water content of rootsoil composite and the fine grain content of soil decreased.In contrast,the root-soil mass ratio and root area ratio initially increased and then decreased with progressive degradation.Under a consistent water content,the tensile strength of root-soil composite followed a pattern of MD>HD>LD>UD.The peak displacement of tensile strength also decreased as the degradation degree of alpine meadow increased.Both the tensile strength and matrix suction of root-soil composite increased as root-soil water content decreased.A root-soil water content of 30.00%-40.00%was found to be the critical threshold for soil cracking in alpine meadows.Within this range,the matrix suction of root-soil composite ranged from 50.00 to 100.00 kPa,resulting in the formation of linear cracks in the surface soil.As the root-soil water content continued to decrease,liner cracks evolved into branch-like and polygonal patterns.The findings of this study provide essential data for improving the mechanical understanding of grassland cracking and its development process.
基金funded by Universiti Teknikal Malaysia Melaka,through Fakulti Teknologi dan Kejuruteraan Mekanikal(FTKM)’s publication fund-K23003.
文摘This study investigates the heat transfer and flow dynamics of a ternary hybrid nanofluid comprising alumina,copper,and silica/titania nanoparticles dispersed in water.The analysis considers the effects of suction,magnetic field,and Joule heating over a permeable shrinking disk.Amathematicalmodel is developed and converted to a systemof differential equations using similarity transformation which then,solved numerically using the bvp4c solver in Matlab software.The study introduces a novel comparative analysis of alumina-copper-silica and alumina-coppertitania nanofluids,revealing distinct thermal conductivity behaviors and identifying critical suction values necessary for flow stabilization.Dual solutions are found within a specific range of parameters such that the minimum required suction values for flow stability,with S_(c)=1.2457 for alumina-copper-silica/water and S_(c)=1.2351 for alumina-coppertitania/water.The results indicate that increasing suction by 1%enhances the skin friction coefficient by up to 4.17%and improves heat transfer efficiency by approximately 1%,highlighting its crucial role in stabilizing the opposing flow induced by the shrinking disk.Additionally,the inclusion of 1%silica nanoparticles reduces both skin friction and heat transfer rate by approximately 0.28%and 0.85%,respectively,while 1%titania concentration increases skin friction by 3.02%but results in a slight heat transfer loss of up to 0.61%.These findings confirm the superior thermal performance of alumina-copper-titania/water,making it a promising candidate for enhanced cooling systems,energy-efficient heat exchangers,and industrial thermal management applications.
基金financially supported by NSERC,CanadaDiscovery Grant 2020(Grant No.5808).
文摘A simplified analytical approach is proposed for predicting the load-displacement behavior of single piles in unsaturated soils considering the contribution from the nonlinear shear strength and soil stiffness influenced by matric suction.This approach includes a Modified Load Transfer Model(MLTM)that can predict the nonlinear relationships between the shear stress and pile-soil relative displacement along the pile shaft,and between the pile base resistance and base settlement.The proposed model is also extended for pile groups to incorporate the interaction effects between individual piles.The analytical approach is validated through a comparative analysis with the measurements from two single pile tests and one pile group test.In addition,a finite element analysis using 3D modeling is carried out to investigate the behavior of pile groups in various unsaturated conditions.This is accomplished with a user-defined subroutine that is written and implemented in ABAQUS to simulate the nonlinear mechanical behavior of unsaturated soils.The predictions derived from the proposed analytical and numerical methods compare well with the measurements of a published experimental study.The proposed methodologies have the potential to be applied in geotechnical engineering practice for the rational design of single piles and pile groups in unsaturated soils.
文摘Maximizing the efficiency of thermal engineering equipment involves minimizing entropy generation,which arises from irreversible processes.This study examines thermal transport and entropy generation in viscous flow over a radially stretching disk,incorporating the effects of magnetohydrodynamics(MHD),viscous dissipation,Joule heating,and radiation.Similarity transformations are used to obtain dimensionless nonlinear ordinary differential equations(ODEs)from the governing coupled partial differential equations(PDEs).The converted equations are then solved by using the BVP4C solver in MATLAB.To validate the findings,the results are compared with previously published studies under fixed parameter conditions,demonstrating strong agreement.Various key parameters are analyzed graphically to assess their impact on velocity and temperature distributions.Additionally,Bejan number and entropy generation variations are presented for different physical parameters.The injection parameter(S<0)increases the heat transfer rate,while the suction parameter(S>0)reduces it,exhibiting similar effects on fluid velocity.The magnetic parameter(M)effectively decreases entropy generation within the range of approximately 0≤η≤0.6.Beyond this interval,its influence diminishes as entropy generation values converge,with similar trends observed for the Bejan number.Furthermore,increased thermal radiation intensity is identified as a critical factor in enhancing entropy generation and the Bejan number.
文摘When tunnelling through low-permeability saturated ground,the pore pressure decreases in the vicinity of the cavity.In certain instances of deep tunnels crossing weak rocks,the pore pressure may even become negative.All existing analytical solutions for the undrained ground response curve(GRC)in the literature assume that the ground fully retains its saturation,in which case the development of negative pore pressures has a stabilising effect e it results in increased effective stresses,and thus shearing resistance,which in turn leads to reduced deformations and plastification.In practice,however,negative pore pressures can induce partial or complete ground desaturation,which may even invalidate the premise of undrained conditions and lead to considerably increased deformations and plastification.In such cases,existing solutions are unsafe for design.The present paper aims to address this shortcoming,by presenting a novel analytical solution for the undrained GRC which incorporates the effect of the excavation-induced desaturation.The solution is derived under the assumption that the ground desaturates completely and immediately under negative pore pressures,which provides the upper bound of deformations and plastification for cases of partial desaturation.The rock is considered to be a linear elastic,brittle-plastic material,obeying a non-associated Mohr-Coulomb(MC)yield criterion.Nevertheless,the solution is also applicable to perfectly plastic rocks via a simple modification of the input parameters.Although the solution is in general semi-analytical,simple closed-form expressions are obtained in the special case of non-dilatant rocks.These expressions are also applicable to rocks exhibiting limited dilatancy,which is usually the case.An application example,based on the planned deep geological repository for radioactive waste in Switzerland,demonstrates the significant practical value and usefulness of the novel solution and underscores its necessity in cases where existing solutions that disregard desaturation are rendered thoroughly unsafe for design.
文摘This study explores the bioconvective behavior of a Reiner-Rivlin nanofluid,accounting for spatially varying thermal properties.The flow is considered over a porous,stretching surface with mass suction effects incorporated into the transport analysis.The Reiner-Rivlin nanofluid model includes variable thermal conductivity,mass diffusivity,and motile microorganism density to accurately reflect realistic biological conditions.Radiative heat transfer and internal heat generation are considered in the thermal energy equation,while the Cattaneo-Christov theory is employed to model non-Fourier heat and mass fluxes.The governing equations are non-dimensionalized to reduce complexity,and a numerical solution is obtained using a shooting method.Parametric studies are conducted to examine the influence of key dimensionless parameters on velocity,temperature,concentration,and motile microorganism profiles.The results are presented through a series of graphs,offering insight into the dynamic interplay between physical mechanisms affecting heat and mass transfer in non-Newtonian bioconvective nanofluid systems.
基金supported by the National Natural Science Foundation of China(Grant Nos.52371301 and 52471289)。
文摘The scaled suction caisson repre sents an innovative design featuring a bio-inspired sidewall modeled after snake skin,commonly utilized in offshore mooring platforms.In comparison with traditional suction caissons,this bio-inspired design demonstrates reduced penetration resistance and enhanced pull-out capacity due to the anisotropic shear behaviors of its sidewall.To investigate the shear behavior of the bio-inspired sidewall under pull-out load,direct shear tests were conducted between the bio-inspired surface and sand.The research demonstrates that the interface shear strength of the bio-inspired surface significantly surpasses that of the smooth surface due to interlocking effects.Additionally,the interface shear strength correlates with the aspect ratio of the bio-inspired surface,shear angle,and particle diameter distribution,with values increasing as the uniformity coefficient Cudecreases,while initially increasing and subsequently decreasing with increases in both aspect ratio and shear angle.The ratio between the interface friction angleδand internal friction angle δ_(s) defines the interface effect factor k.For the bio-inspired surface,the interface effect factor k varies with shear angleβ,ranging from 0.9 to 1.12.The peak value occurs at a shear angleβof 60°,substantially exceeding that of the smooth surface.A method for calculating the relative roughness R_(N) is employed to evaluate the interface roughness of the bio-inspired surface,taking into account scale dimension and particle diameter distribution effects.
文摘Characteristics of heat transfer and flow of Newtonian and non-Newtonian fluids through porous walls and in porous media are studied due to their wide range of applications including geothermal reservoirs,heat exchangers,marine propulsion,and aerodynamics.The current study investigates the characteristics of heat transport in a reactive third-grade fluid,moving through permeable parallel plates,with uniform suction/injection velocity.The two permeable,parallel plates are maintained at the same,constant temperature.After being transformed into its dimensionless equivalent,governing equations are solved by employing the Least Squares Method(LSM).The LSM results are further validated with numerical solutions for temperature and velocity.The impact of cross-flow Reynolds number,Peclet number,heat generation parameter,non-Newtonian parameter,and Brinkman number on entropy generation,velocity,temperature,and Bejan number are investigated.Theresults indicate that temperature distribution is significantly influenced by the third-grade fluid parameter.The maximum temperature drops from almost 0.12 to 0.10 as the third-grade fluid parameter increases from0.05 to 0.4.When the cross-flow Reynolds number is raised from 0.05 to 3,the maximum temperature drops from 0.12 to around 0.09.Temperature is strongly influenced by the heat generation parameter.A greater understanding of the thermal characteristics necessary for the design of a variety of systems,such as heat exchangers,marine propulsion,aerodynamic systems,etc.,may be gained from the findings of the current study.
基金funded by the Australian Research Council via the ARC Linkage(Grant No.LP16160100649).
文摘The complex behaviors of expansive soils,particularly their volumetric changes driven by moisture variations,pose significant challenges in urban geotechnical engineering.Although vegetation-induced moisture changes are known to affect ground movement,quantitative characterization of tree–soil interactions remains limited due to insufficient field data and unclear relationships between tree water uptake and soil response.This study investigates the mechanical behavior of expansive clay soils influenced by two Lophostemon confertus samples during a 14-month field monitoring program in Melbourne,Australia.The research methodology integrates measurements of soil displacement,total soil suction,moisture content,and tree water consumption through instrumentation and monitoring systems.Field measurements suggest that tree roots reached the limits of their water extraction capacity when total soil suction exceeded 2880 kPa within the active root zone.The spatial extent of tree-induced soil desiccation reached 0.6–0.7 times the tree height laterally and penetrated to depths of 2.5–3.3 m vertically.The mature sample,with an 86%greater crown area and a threefold larger sapwood area,exhibited 142%higher water consumption(35 kL),demonstrating the scalability of tree–soil interaction mechanisms.A multiple linear regression model was developed to quantify the coupled relationships between soil movement and key variables,achieving a high adjusted R2 value of 0.97,which provides engineers and practitioners with a practical tool for estimating ground movement near trees.These findings offer valuable insights for infrastructure design in tree-adjacent environments and can inform computational models and design codes to enable more accurate site assessments and sustainable urban development.
基金supported by the National Natural Science Foundation of China(Grant No.41825018)Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA23090402)the National Natural Science Foundation of China(Grant No.42141009).
文摘Experimental research into the hydraulic conductivity curve (HCC) of unsaturated soil is limited due to the inherent challenge associated with labor, cost, and time. Typically, the HCC is estimated using the soil water characteristic curve (SWCC) based models and saturated hydraulic conductivity (SHC). However, the efficiency of the SWCC-based model is rarely assessed, and the influence of soil density and pore structure on HCC remains incomplete due to limited experimental data. To address this gap, this study employs an innovative filter-paper-based column method, which can measure the HCC over a wide suction range (e.g. 0−105 kPa), to capture the HCCs of both intact and compacted specimens with varying dry densities. The efficiency of two typical SWCC-based models is assessed using the measured data. Meanwhile, the mercury intrusion porosity (MIP) technique is employed to obtain the pore characteristic (i.e. pore size distribution (PSD)) and a method of predicting the HCC using the PSD data is proposed, emphasizing the dominant role of the pore structure in shaping the HCC. The results reveal that the dry density's influence on the HCC is primarily observed within the low suction range, corresponding to variations in the dominant and large pores. In the high suction range, the HCCs align along a linear trajectory when plotted in a log-log format. A notable finding is the overestimation of the HCC obtained from the SWCC-based models using the measured SHC. When the SHC is regarded as a fitting parameter, good agreement is achieved. The adjusted SHC value is typically 0-1 order of magnitude lower than the measured value, and this discrepancy diminishes as dry density increases. On the other hand, the proposed PSD-based model performs well with the measured SHC data. Caution is exercised when using the SHC to estimate the HCC for modeling water movement in partially saturated soil.
基金supported by the research project from the Ministry of Higher Education and Science of the Republic of Kazakhstan(Grant No.AP19675456)Nazarbayev University Collaborative Research Program(CRP)(Grant No.111024CRP2010)Collaborative Research Program(CRP)(Grant No.111024CRP2011).
文摘Unsaturated soil mechanics is crucial in understanding ground conditions and constructing geotechnical structures,particularly amidst the challenges posed by global climate change.Nevertheless,acquiring accurate soil suction values remains challenging due to limitations in existing methodologies,such as susceptibility to cavitation,high costs,and time-intensive procedures.Hence,this study employs a high-suction polymer sensor(HSPS)to evaluate the polymer's performance in determining soil suction.Subsequently,the polymers were used to measure unsaturated soil properties,especially soil-water characteristics curves(SWCC),based on osmotic principles.Five polymer samples classified as superabsorbent polymers(SAP)were synthesized with varying degrees of crosslinking,and their properties were assessed through swelling test and Fourier-transform infrared spectroscopy(FTIR).The soil sample from Turan,located within Nazarbayev University,was analyzed using a bimodal equation to determine the best fit.Results revealed that the swelling value and structural integrity of the polymer significantly affect soil suction capacity,with the findings being deemed temperature-independent,thereby obviating the need for calibration.Two potential factors hindering suction increase were identified:cavitation within the polymer or a reduction in the osmotic gradient due to polymer transformation into hydrogel formation.Overall,the novel polymer shows promise as an alternate material for SWCC measurement considering its simple method and being more sustainable compared to the other polymers,although further investigation is required to enhance the suction potential.
基金support for this work was provided by the National Natural Science Foundation of China(No.52206060)the National Science and Technology Major Project of China(Nos.J2019-Ⅱ-0021-0042 and J2019-Ⅱ-0002-0022).
文摘The design of high-lift Low-Pressure Turbines(LPTs)causes the separation of the boundary layer on the suction side of the blade and leads to a strong secondary flow.This present study aims to minimize secondary losses through endwall slot suction and incoming wakes in a front-loaded high-lift LPT cascade with Zweifel of 1.58 under low Reynolds number of 25000.Two slotted schemes for the boundary layer of the endwall were designed(Plan A and Plan B),and the effects of suction mass flow on secondary flow were studied.The underlying physics of the endwall boundary layer of the suction and secondary flow under unsteady wakes was discussed.The results show that slot suction at the endwall boundary layer can significantly suppress the secondary flow by removing low-momentum fluids.Plans A and B significantly reduced the secondary kinetic energy by 44.2%and 36.9%,respectively,compared with the baseline cascade at the suction mass flow ratios of 1%.With an increase in the mass flow ratio of suction,the secondary flow was gradually reduced in both Plans A and B.It is more beneficial to control the secondary flow to destroy the intersection of the pressure side and suction side of the horseshoe vortex before it develops into a passage vortex.Under unsteady wakes,the combined effects of incoming wakes and endwall boundary layer suction can further suppress the secondary flow at the suction mass flow ratios of 2%for Plan A,because the positive and negative vorticity inside upstream wakes accelerated the mixing of the main flow and secondary flow and thus increased the energy of secondary vortices.
基金National Natural Science Foundation of China under Grant Nos.52208345,52008124,52268054the Opening Fund of State Key Laboratory of Geohazard Prevention and Geoenvironment Protection under Grant No.SKLGP2022K002+1 种基金the Natural Science Foundation of Jiangsu Province under Grant No.BK20210479the Fundamental Research Funds for the Central Universities under Grant No.JUSRP121055。
文摘Earthquake-induced slope failures are common occurrences in engineering practice and pre-stressed anchor cables are an effective technique in maintaining slope stability,especially in areas that are prone to earthquakes.Furthermore,the soil at typical engineering sites also exhibit unsaturated features.Explicit considerations of these factors in slope stability estimations are crucial in producing accurate results.In this study,the seismic responses of expansive soil slopes stabilized by anchor cables is studied in the realm of kinematic limit analysis.A modified horizontal slice method is proposed to semi-analytically formulate the energy balance equation.An illustrative slope is studied to demonstrate the influences of suction,seismic excitations and anchor cables on the slope stability.The results indicate that the stabilizing effect of soil suction relates strongly to the seismic excitation and presents a sine shape as the seismic wave propagates.In higher and steeper slopes,the stabilizing effect of suction is more evident.The critical slip surface tends to be much more shallow as the seismic wave approaches the peak and vice versa.
文摘The tripod foundation(TF)is a prevalent foundation configuration in contemporary engineering practices.In comparison to a single pile,TF comprised interconnected individual piles,resulting in enhanced bearing capacity and stability.A physical model test was conducted within a sandy soil foundation,systematically varying the length-to-diameter ratio of the TF.The investigation aimed to comprehend the impact of altering the height of the central bucket on the historical horizontal bearing capacity of the foundation in saturated sand.Additionally,the study scrutinized the historical consequences of soil pressure and pore water pressure surrounding the bucket throughout the loading process.The historical findings revealed a significant enhancement in the horizontal bearing capacity of the TF under undrained conditions.When subjected to a historical horizontal loading angle of 0°for a single pile,the multi-bucket foundation exhibited superior historical bearing capacity compared to a single-pile foundation experiencing a historical loading angle of 180°under pulling conditions.With each historical increment in bucket height from 150 mm to 350 mm in 100 mm intervals,the historical horizontal bearing capacity of the TF exhibited an approximately 75%increase relative to the 150 mm bucket height,indicating a proportional relationship.Importantly,the historical internal pore water pressure within the bucket foundation remained unaffected by drainage conditions during loading.Conversely,undrained conditions led to a historical elevation in pore water pressure at the lower side of the pressure bucket.Consequently,in practical engineering applications,the optimization of the historical bearing efficacy of the TF necessitated the historical closure of the valve atop the foundation to sustain internal negative pressure within the bucket.This historical measure served to augment the historical horizontal bearing capacity.Simultaneously,historical external loads,such as wind,waves,and currents,were directed towards any individual bucket within the TF for optimal historical performance.
文摘Purpose-The experiments of this study investigated the effect of the subgrade degree of saturation on the value of the stresses generated on the surface and the middle(vertical and lateral stresses).The objectives of this study can be identified by studying the effect of subgrade layer degree of saturation variation,load amplitude and load frequency on the transmitted stresses through the ballast layer to the subgrade layer and the stress distribution inside it and investigating the excess pore water pressure development in the clay layer in the case of a fully saturated subgrade layer and the change in matric suction in the case of an unsaturated subgrade layer.Design/methodology/approach-Thirty-six laboratory experiments were conducted using approximately half-scale replicas of real railways,with an iron box measuring 1.5×1.031.0 m.Inside the box,a 0.5 m thick layer of clay soil representing the base layer was built.Above it is a 0.2 m thick ballast layer made of crushed stone,and on top of that is a 0.8 m long rail line supported by three 0.9 m(0.1×0.1 m)slipper beams.The subgrade layer has been built at the following various saturation levels:100,80,70 and 60%.Experiments were conducted with various frequencies of 1,2 and 4 Hz with load amplitudes of 15,25 and 35 kN.Findings-The results of the study demonstrated that as the subgrade degree of saturation decreased from 100 to 60%,the ratio of stress in the lateral direction to stress in the vertical direction generated in the middle of the subgrade layer decreased as well.On average,this ratio changed from approximately 0.75 to approximately 0.65.Originality/value-The study discovered that as the test proceeded and the number of cycles increased,the value of negative water pressure(matric suction)in the case of unsaturated subgrade soils declined.The frequency of loads had no bearing on the ratio of decline in matric suction values,which was greater under a larger load amplitude than a lower one.As the test progressed(as the number of cycles increased),the matric suction dropped.For larger load amplitudes,there is a greater shift in matric suction.The change in matric suction is greater at higher saturation levels than it is at lower saturation levels.Furthermore,it is seen that the load frequency value has no bearing on how the matric suction changes.For all load frequencies and subgrade layer saturation levels,the track panel settlement rises with the load amplitude.Higher load frequency and saturation levels have a greater impact.
基金LMP acknowledges financial support from ANID through Convocatoria Nacional Subvención a Instalación en la Academia Convocatoria Año 2021,Grant SA77210040。
文摘We report on the magnetohydrodynamic impact on the axisymmetric flow of Al_(2)O_(3)/Cu nanoparticles suspended in H_(2)O past a stretched/shrinked sheet.With the use of partial differential equations and the corresponding thermophysical characteristics of nanoparticles,the physical flow process is illustrated.The resultant nonlinear system of partial differential equations is converted into a system of ordinary differential equations using the suitable similarity transformations.The transformed differential equations are solved analytically.Impacts of the magnetic parameter,solid volume fraction and stretching/shrinking parameter on momentum and temperature distribution have been analyzed and interpreted graphically.The skin friction and Nusselt number were also evaluated.In addition,existence of dual solution was deduced for the shrinking sheet and unique solution for the stretching one.Further,Al_(2)O_(3)/H_(2)O nanofluid flow has better thermal conductivity on comparing with Cu/H_(2)O nanofluid.Furthermore,it was found that the first solutions of the stream are stable and physically realizable,whereas those of the second ones are unstable.
