Dynamic fracture behaviour of crack curving in bent beams has been investigated. In order to understand the propagation mechanism of such cracks under impact, an experimental method is used that combines dynamic photo...Dynamic fracture behaviour of crack curving in bent beams has been investigated. In order to understand the propagation mechanism of such cracks under impact, an experimental method is used that combines dynamic photoelasticity with dynamic caustics to study the interaction of the flexural waves and the crack. From the state change of the transient stresses in polymer specimen, the curving fracture in the impulsively loaded beams is analyzed. The dynamic responses of crack tips are evaluated by the stress intensity factors for the cracks running in varying curvature paths under bending stress wave.展开更多
To study the curving performance of trains, 1D and 3D dynamic models of trains were built using nu- merical methods. The 1D model was composed of 210 simple wagons, each allowed only longitudinal motion; whereas the 3...To study the curving performance of trains, 1D and 3D dynamic models of trains were built using nu- merical methods. The 1D model was composed of 210 simple wagons, each allowed only longitudinal motion; whereas the 3D model included three complicated wagons for which longitudinal, lateral, and vertical degrees of freedom were considered. Combined with the calculated results from the 1D model under braking conditions, the behavior of draft gears and brake shoes were added to the 3D model. The assessment of the curving performance of trains was focused on making comparisons between idling and braking conditions. The results indicated the following： when a train brakes on a curved track, the wheel-rail lateral force and derailment factor are greater than under idling conditions. Because the yawing movement of the wheelset is limited by brake shoes, the zone of wheel contact along the wheel tread is wider than under idling conditions. Furthermore, as the curvature becomes tighter, the traction ratio shows a nonlinear increasing trend, whether under idling or braking conditions. By increasing the brake shoe pressure, train steering becomes more difficult.展开更多
By using tilting carbodies, train can negotiate at a higher speed withoutreducing the passenger's ride quality. This is a good method to allow a significant increase inspeed at existing track to improve the railwa...By using tilting carbodies, train can negotiate at a higher speed withoutreducing the passenger's ride quality. This is a good method to allow a significant increase inspeed at existing track to improve the railway transportation capability, and to enhance thecompetition ability of railways with other transportation systems. With the increase of the curvenegotiation speed, the wheel-rail lateral forces and wheel-rail wear of the tilting train willincrease. The self-steering radial bogie is an effective way to solve the problem. The dynamic modelof the tilting passenger car with self-steering bogies is established in detail, and the curvingperformance of the car is investigated.展开更多
By means of ink trace visualization of the flows in conventional straight, positively curved and negatively curved cascades with tip clearance, and measurement of the aerodynamic parameters in the transverse section, ...By means of ink trace visualization of the flows in conventional straight, positively curved and negatively curved cascades with tip clearance, and measurement of the aerodynamic parameters in the transverse section, and by appling topology theory, the structures on both endwalls and blade surfaces were analyzed. Compared with conventional straight cascade, blade positive curving eliminates the separation line of the upper passage vortex and leads the secondary vortex to change from close separation to open separation, while blade negative curving effects merely the positions of singular points and the intensities and scales of vortex.展开更多
By means of ink trace visualization of the flows in conventional straight, positively curved and negatively curved cascades with tip clearance, and measurement of the aerodynamic parameters in transverse section, and...By means of ink trace visualization of the flows in conventional straight, positively curved and negatively curved cascades with tip clearance, and measurement of the aerodynamic parameters in transverse section, and by appling topology theory, the topological structures and vortex structure in the transverse section of a blade cascade were analyzed. Compared with conventional straight cascade, blade positive curving eliminates the separation line of the upper passage vortex, and leads the secondary vortex to change from close separation to open separation, while blade negative curving effects merely the positions of singular points and the intensities and scales of vortex.展开更多
Based on the theory of vehicle-track coupling dynamics,the coupling dynamic model of the freight car mounted with the sub-frame bogies and the numerical model of curved track were established,utilizing the fast numeri...Based on the theory of vehicle-track coupling dynamics,the coupling dynamic model of the freight car mounted with the sub-frame bogies and the numerical model of curved track were established,utilizing the fast numerical integration method,the curving performance of the vehicle was simulated to study the influence of the curve geometric parameters such as curve radius,transition curve length and superelevation of outer rail on the wheel-rail dynamic interaction.The simulation results indicate that:(1)Increasing the curve radius can decrease the wheel-rail wear,but the effect will weaken while the curve radius is greater than 800m.(2)If the transition curve length is less than 30m,vibrations will appear at the transition-circle connecting point,and the smaller the transition length,the bigger the vibrations,the worse the wheel-rail wear,but when the length is bigger than 50m,its further variation has very little effect on wheel-rail wear.(3)The superelevation of outer rail can affect the distribution and difference of the inner and outer wheel-rail forces,and too large deficient or excessive superelevation will worsen the wheel-rail wear either.However,an appropriate deficient superelevation of outer rail(e.g.<20mm)is helpful to reduce the wheel-rail wear,which is consistent with the engineering practice of settling a certain deficient superelevation value.展开更多
Pores among particles provide the main space for the storage and migration of deep underground fluids(such as oil,gas,groundwater,and unconventional natural gas).The pores form a pore structure with complex morphology...Pores among particles provide the main space for the storage and migration of deep underground fluids(such as oil,gas,groundwater,and unconventional natural gas).The pores form a pore structure with complex morphology which is mainly dominated by the shape and distribution of particles.Therefore,the reconstruction of the pore structure or granular porous media and the evaluation of particle roundness have become an important foundation for the study of fluid flow through deep underground rock mass.This research proposes a novel approach for the multi-scale model with angular vertexes.The fractal topology theory and Voronoi space segmentation technology are combinedly used for the reconstruction of fractal granular porous media.The angular shapes are smoothed by using a modified B-spline technique and the particles with varying degrees of roundness are generated.To validate the superiority of our approach,the roundness based on the Wadell roundness calculation method is calculated and compared with the roundness obtained from particles smoothed using the vertex rounding substitution method.Results show that the roundness of particles smoothed with the modified B-spline technique closely aligns with the corresponding set rounded level(a nondimensional variable).Conversely,the vertex rounding substitution method is limited to a single dimensionally rounded radius.This innovative approach can offer a new method for the construction of granular porous media for the fluid flow study in deep underground rock mass.展开更多
Kinesin-8 motors can move with a high processivity on microtubule lattices toward the plus end.After reaching the plus end,the kinesin-8 motors can pause for a long time and promote the microtubule depolymerization.He...Kinesin-8 motors can move with a high processivity on microtubule lattices toward the plus end.After reaching the plus end,the kinesin-8 motors can pause for a long time and promote the microtubule depolymerization.Here,using atomistic molecular dynamics simulations we studied the structural changes of the kinesin-8 head in different nucleotide states bound to the straight and curved tubulins and the corresponding interactions between them.We found that the kinesin-8 head in ATP and/or ADP–Pi state has the similar strong affinity while in ADP state has the similar weak affinity to both the straight and curved tubulins,which is strongly implicated in the mechanism of the long but very different residence times of the kinesin-8 motor on the microtubule lattice and at the end.Moreover,we found that loop-2 of the kinesin-8 head bound strongly to the curved tubulin in the stable state has a large interference with its neck linker pulled in the minusended orientation.This is contrary to the case of the head bound strongly to the straight tubulin,where loop-2 has little interference with its neck linker pulled in the minus-ended orientation.The large interference can induce a larger internal force between the two heads and thus can induce the two curved tubulins bound strongly by the two heads to be more curved relative to each other.This is strongly implicated in the mechanism of the depolymerase activity of the kinesin-8motors and explains the origin of loop-2 playing a facilitating role in the depolymerase activity.展开更多
Elliptic curve(EC)based cryptosystems gained more attention due to enhanced security than the existing public key cryptosystems.A substitution box(S-box)plays a vital role in securing modern symmetric key cryptosystem...Elliptic curve(EC)based cryptosystems gained more attention due to enhanced security than the existing public key cryptosystems.A substitution box(S-box)plays a vital role in securing modern symmetric key cryptosystems.However,the recently developed EC based algorithms usually trade off between computational efficiency and security,necessitating the design of a new algorithm with the desired cryptographic strength.To address these shortcomings,this paper proposes a new scheme based onMordell elliptic curve(MEC)over the complex field for generating distinct,dynamic,and highly uncorrelated S-boxes.Furthermore,we count the exact number of the obtained S-boxes,and demonstrate that the permuted version of the presented S-box is statistically optimal.The nonsingularity of the presented algorithm and the injectivity of the resultant output are explored.Rigorous theoretical analysis and experimental results demonstrate that the proposedmethod is highly effective in generating a large number of dynamic S-boxes with adequate cryptographic properties,surpassing current state-of-the-art S-box generation algorithms in terms of security.Apart fromthis,the generated S-box is benchmarked using side-channel attacks,and its performance is compared with highly nonlinear S-boxes,demonstrating comparable results.In addition,we present an application of our proposed S-box generator by incorporating it into an image encryption technique.The encrypted and decrypted images are tested by employing extensive standard security metrics,including the Number of Pixel Change Rate,the Unified Average Changing Intensity,information entropy,correlation coefficient,and histogram analysis.Moreover,the analysis is extended beyond conventional metrics to validate the new method using advanced tests,such as the NIST statistical test suite,robustness analysis,and noise and cropping attacks.Experimental outcomes show that the presented algorithm strengthens the existing encryption scheme against various well-known cryptographic attacks.展开更多
This study explores the thin-layer convective solar drying of Marrubium vulgare L.leaves under conditions typical of sun-rich semi-arid climates.Drying experiments were conducted at three inlet-air temperatures(40℃,5...This study explores the thin-layer convective solar drying of Marrubium vulgare L.leaves under conditions typical of sun-rich semi-arid climates.Drying experiments were conducted at three inlet-air temperatures(40℃,50℃,60℃)and two air velocities(1.5 and 2.5 m·s^(-1))using an indirect solar dryer with auxiliary temperature control.Moisture-ratio data were fitted with eight widely used thin-layer models and evaluated using correlation coefficient(r),root-mean-square error(RMSE),and Akaike information criterion(AIC).A complementary heattransfer analysis based on Reynolds and Prandtl numbers with appropriate Nusselt correlations was used to relate flow regime to drying performance,and an energy balance quantified the relative contributions of solar and auxiliary heat.The logarithmic model consistently achieved the lowest RMSE/AIC with r>0.99 across all conditions.Higher temperature and air velocity significantly reduced drying time during the decreasing-rate period,with no constantrate stage observed.On average,solar input supplied the large majority of the thermal demand,while the auxiliary heater compensated short irradiance drops to maintain setpoints.These findings provide a reproducible dataset and a modelling benchmark for M.vulgare leaves,and they support energy-aware design of hybrid solar dryers formedicinal plants in sun-rich regions.展开更多
Suffusion refers to the loss of fineparticles within the soil matrix without any associated volume change,induced by hydrodynamic forces.This study investigated the suffusion of sand-clay mixtures through one-dimensio...Suffusion refers to the loss of fineparticles within the soil matrix without any associated volume change,induced by hydrodynamic forces.This study investigated the suffusion of sand-clay mixtures through one-dimensional soil column experiments under a stepwise increase in hydraulic gradient(i),aiming to evaluate the critical hydraulic gradient(icrit)as a function of the size ratio between sand and clay,clay type,and ionic concentration.It was found that icrit was less than 0.1 for all sand-clay mixtures examined in this study.In addition,the lower peak concentrations of filtrated clay observed in sand-illite mixtures,compared to those of sand-kaolinite mixtures at the same level of i,suggest that illite particles are more susceptible to suffusion.Overall,the observed breakthrough curves,mass fraction of filtrated clay,volume of outflow,and total injection time presented in this study highlight the importance of considering clay type,sand-to-clay size ratio,and ionic concentration when assessing the suffusion behavior of clay-containing soils under a stepwise increase in hydraulic gradient.展开更多
Objectives:Uretero-enteric strictures are feared complications following cystectomy.Despite surgical advancements,particularly the rise of robot-assisted approaches,the risk factors associated with these strictures re...Objectives:Uretero-enteric strictures are feared complications following cystectomy.Despite surgical advancements,particularly the rise of robot-assisted approaches,the risk factors associated with these strictures remain poorly defined.This study aimed to identify the risk factors associated with uretero-enteric anastomotic strictures after cystectomy,according to the surgical approach and type of urinary diversion(extracorporeal vs.intracorporeal).Methods:We conducted a single-center retrospective study including 340 patients who underwent cystectomy between 2016 and 2024 at Tours University Hospital.Clinical,biological,perioperative,and postoperative data were analyzed.The occurrence of a uretero-ileal anastomotic stricture was defined radiologically by a uretero-hydronephrosis≥20 mm.We constructed and analyzed a learning curve for robotic surgery with intracorporeal urinary diversion.Results:Strictures occurred in 60 patients(17.6%).On multivariable analysis,reduced preoperative glomerular filtration rate(odds ratio[OR]=1.45 per 10 mL/min decrease,95%CI[1.12-1.87],p=0.004),elevated creatinine(OR=1.30 per 10μmol/L increase,95%CI[1.05-1.61],p=0.018),prior myocardial infarction(OR=2.25,95%CI[1.10-4.62],p=0.027),and postoperative urinary tract infection(OR=3.10,95%CI[1.65-5.82],p<0.001)were independent predictors.Most strictures were left-sided.Intracorporeal robotic diversion had a higher,though non-significant,stricture rate(21.5%vs.15.2%,OR=1.52,p=0.12).Stricture rates fell markedly after 20 robotic cases per surgeon(23.8%vs.12.1%).Conclusion:Uretero-enteric strictures are multifactorial,strongly influenced by baseline renal function,cardiovascular comorbidity,and postoperative infection.Robotic intracorporeal diversion shows a learning curve effect,underlining the importance of surgical expertise and infection prevention in reducing risk.展开更多
In this paper,we study the nonlinear Riemann boundary value problem with square roots that is represented by a Cauchy-type integral with kernel density in variable exponent Lebesgue spaces.We discuss the odd-order zer...In this paper,we study the nonlinear Riemann boundary value problem with square roots that is represented by a Cauchy-type integral with kernel density in variable exponent Lebesgue spaces.We discuss the odd-order zero-points distribution of the solutions and separate the single valued analytic branch of the solutions with square roots,then convert the problem to a Riemann boundary value problem in variable exponent Lebesgue spaces and discuss the singularity of solutions at individual zeros belonging to curve.We consider two types of cases those where the coefficient is Hölder and those where it is piecewise Hölder.Then we solve the Hilbert boundary value problem with square roots in variable exponent Lebesgue spaces.By discussing the distribution of the odd-order zero-points for solutions and the method of symmetric extension,we convert the Hilbert problem to a Riemann boundary value problem.The equivalence of the transformation is discussed.Finally,we get the solvable conditions and the direct expressions of the solutions in variable exponent Lebesgue spaces.展开更多
The capillary pressure curve provides fundamental insights into the dynamics of fluid-fluid displacement and phase distributions.Capillary scaling is crucial for extrapolating capillary pressure-saturation data from l...The capillary pressure curve provides fundamental insights into the dynamics of fluid-fluid displacement and phase distributions.Capillary scaling is crucial for extrapolating capillary pressure-saturation data from laboratory tests to field applications.However,the classic scaling method fails to capture the effect of wettability as the pore surface approaches neutral wetting.Here,inspired by the role of pore-filling events in controlling fluid-fluid displacement,we perform a theoretical analysis of the burst events occurring during drainage processes.We find that the median threshold capillary pressure,which corresponds to the occurrence of burst events for the median pore throat,is closely correlated with the capillary pressure curve across various contact angles.Using this concept,we propose a new scaling method for capillary pressure curves under various wetting conditions.We conduct microfluidic experiments and pore-network modeling across different contact angles,porosities,and disorders to evaluate the new scaling methods,indicating that the new scaling method performs better than the Leverett J-function as the contact angle approaches 90°.We further perform geometry analysis on the critical radius of curvature for burst events in an ideal tetrahedral arrangement and extend the new scaling method to 3D(three-dimensional)porous media.Model evaluation shows that the 3D version of the scaling method also performs well but requires fewer parameters compared to the Leverett J-function.Our work enhances the prediction and interpretation of experimental data for capillary pressure curves under various wet conditions,and more importantly,establishes a methodology that relates Darcy-scale flow behavior to pore-scale fluid displacements.展开更多
The increasing production and release of synthetic organic chemicals,including pharmaceuticals,into our envi-ronment has allowed these substances to accumulate in our surface water systems.Current purification technol...The increasing production and release of synthetic organic chemicals,including pharmaceuticals,into our envi-ronment has allowed these substances to accumulate in our surface water systems.Current purification technolo-gies have been unable to eliminate these pollutants,resulting in their ongoing release into aquatic ecosystems.This study focuses on cloperastine(CPS),a cough suppressant and antihistamine medication.The environmental impact of CPS usage has become a concern,mainly due to its increased detection during the COVID-19 pandemic.CPS has been found in wastewater treatment facilities,effluents from senior living residences,river waters,and sewage sludge.However,the photosensitivity of CPS and its photodegradation profile remain largely unknown.This study investigates the photodegradation process of CPS under simulated tertiary treatment conditions using UV photolysis,a method commonly applied in some wastewater treatment plants.Several transformation prod-ucts were identified,evaluating their kinetic profiles using chemometric approaches(i.e.,curve fitting and the hard-soft multivariate curve resolution-alternating least squares(HS-MCR-ALS)algorithm)and calculating the reaction quantum yield.As a result,three different transformation products have been detected and correctly identified.In addition,a comprehensive description of the kinetic pathway involved in the photodegradation process of the CPS drug has been provided,including observed kinetic rate constants.展开更多
This study investigates the effect of Ce content on the hydrogen storage properties of Ti_(0.98)Zr_(0.02)Mn_(1.5)Cr_(0.05)V_(0.43)Fe_(0.09)Ce_(x)(x=0,0.02,0.04,and 0.06,at%)alloys.Microstructural analysis of these all...This study investigates the effect of Ce content on the hydrogen storage properties of Ti_(0.98)Zr_(0.02)Mn_(1.5)Cr_(0.05)V_(0.43)Fe_(0.09)Ce_(x)(x=0,0.02,0.04,and 0.06,at%)alloys.Microstructural analysis of these alloys revealed dendritic microstructures without the segregation of chemical elements,with the C14 Laves phase identified as the dominant phase.After two activation cycles at 4 MPa and 293 K,the alloys exhibited excellent hydrogen absorption properties.The addition of Ce significantly improved the kinetics of the alloys.At x=0.02,the hydrogen absorption capacity reached 90%of its maximum within 137 s at 293 K.Pressure-composition-temperature curves indicated that hydrogen absorption capacity initially increased first and then decreased with increasing Ce content,reaching a maximum value of 1.85wt%at x=0.04.Thermodynamic results demonstrated that the enthalpy and entropy of hydrogen absorption followed a similar trend,which was consistent with the variation in hydrogen storage capacity.Thus,the improvement in hydrogen absorption capacity due to the addition of Ce is attributed to the increase in enthalpy.The increase of the lattice constant in the C14 Laves phase and the deoxidization effect of Ce are expected to be beneficial for the improvement of hydrogen absorption kinetics.展开更多
The present study investigates the flow,heat,and mass transfer analysis in the bioconvection of nanofluid containing motile gyrotactic microorganisms through a semi-porous curved oscillatory channel with a magnetic fi...The present study investigates the flow,heat,and mass transfer analysis in the bioconvection of nanofluid containing motile gyrotactic microorganisms through a semi-porous curved oscillatory channel with a magnetic field.These microorganisms produce density gradients by swimming,which induces macroscopic convection flows in the fluid.This procedure improves the mass and heat transfer,illustrating the interaction between biological activity and fluid dynamics.Furthermore,instead of considering traditional Fourier's and Fick's law the energy and concentration equations are developed by incorporating Cattaneo-Christov double diffusion theory.Moreover,to examine the influence of thermophoresis and Brownian diffusions in the fluid we have adopted the Buongiorno nanofluid model.Due to the oscillation of the surface of the channel,the mathematical development of the considered flow problem is obtained in the form of partial differential equations via the curvilinear coordinate system.The convergent series solution of the governing flow equations is obtained after applying the homotopy analysis method(HAM).The effects of different pertinent flow parameters on velocity,motile microorganism density distribution,concentration,pressure,temperature,and skin friction coefficient are examined and discussed in detail with the help of graphs and tables.It is observed during the current study that the density of microorganisms is enhanced for higher values of Reynolds number,Peclet number,radius of curvature variable,and Lewis number.展开更多
The original online version of this article was revised:The layout update for Article 758 has impacted the page range in the published issue,but did not affect the scholarly content.To ensure consistency with the orig...The original online version of this article was revised:The layout update for Article 758 has impacted the page range in the published issue,but did not affect the scholarly content.To ensure consistency with the originally assigned pages(2595-2614),we will need to publish an erratum to correct the article and restore the original page range.The original article has been corrected.展开更多
BACKGROUND Living donor kidney transplantation is the optimal method of long-term renal replacement therapy.Minimally invasive donor nephrectomy techniques,such as robot-assisted(RALDN)and hand-assisted(HALDN)laparosc...BACKGROUND Living donor kidney transplantation is the optimal method of long-term renal replacement therapy.Minimally invasive donor nephrectomy techniques,such as robot-assisted(RALDN)and hand-assisted(HALDN)laparoscopic procedures,are well-established in high-income countries and are being increasingly adopted worldwide.Nevertheless,no studies have reported surgical outcomes of RALDN donor nephrectomy from a United Kingdom center to date.AIM To compare surgical outcomes between RALDN and HALDN laparoscopic donor nephrectomy in a United Kingdom high-volume living kidney donor transplant program.METHODS A case-control matching analysis was performed based on the following parameters:Sex,age,body mass index,procedure laterality,number of renal arteries,and previous abdominal surgeries.Key surgical outcomes,including primary warm ischemia time,operative duration,and post-operative recovery,were evaluated.RESULTS In this cohort of 140 living donors(70 RALDN vs 70 HALDN),donor and recipient outcomes were equivalent across key metrics:Pain scores,overall complication rates,readmissions,reoperations,and creatinine levels at 30 days and 1 year.Recipient long-term renal function did not differ between groups.Operative time for RALDN decreased significantly over the study period,indicating progressive improvement along the learning curve.Although RALDN was associated with a modestly longer mean warm ischaemia time(3.53 minutes vs 2.76 minutes,P<0.001)and extended hospital stay(4.21 days vs 3.17 days,P<0.001),these did not translate into any disadvantage in clinical outcomes.CONCLUSION In this first United Kingdom comparative cohort,RALDN demonstrated excellent safety and efficacy,even in the early phase of our programme,matching the outcomes of the well-established,gold-standard HALDN approach.Moreover,the pronounced learning-curve trajectory suggests considerable potential for further improvements in robotic surgical outcomes as the programme matures.展开更多
Floquet engineering provides a powerful and flexible method for modifying the band structures of quantum materials.While circularly polarized light has been shown to convert curved nodal lines in three-dimensional sem...Floquet engineering provides a powerful and flexible method for modifying the band structures of quantum materials.While circularly polarized light has been shown to convert curved nodal lines in three-dimensional semimetals into Weyl points,such a transformation is forbidden for an isolated straight nodal line.In this work,we uncover a dramatic shift in this paradigm when multiple straight nodal lines intersect.We observe that circularly polarized light not only gaps them into Weyl points but also induces unprecedented surface-state Fermi arcs that extend across the entire surface Brillouin zone and form a linked topological structure.These findings advance our fundamental understanding of light-driven transitions in topological semimetals and unveil a unique Weyl semimetal phase defined by linked Fermi arcs.We discuss potential exotic phenomena arising from this phase,applications of our predictions to spin-split antiferromagnets,and the extension of this Weyl semimetal phase to classical systems.展开更多
基金The project supported by the National Natural Science Foundation of Chinathe Scientific Commussion of Yunnan Province of China
文摘Dynamic fracture behaviour of crack curving in bent beams has been investigated. In order to understand the propagation mechanism of such cracks under impact, an experimental method is used that combines dynamic photoelasticity with dynamic caustics to study the interaction of the flexural waves and the crack. From the state change of the transient stresses in polymer specimen, the curving fracture in the impulsively loaded beams is analyzed. The dynamic responses of crack tips are evaluated by the stress intensity factors for the cracks running in varying curvature paths under bending stress wave.
文摘To study the curving performance of trains, 1D and 3D dynamic models of trains were built using nu- merical methods. The 1D model was composed of 210 simple wagons, each allowed only longitudinal motion; whereas the 3D model included three complicated wagons for which longitudinal, lateral, and vertical degrees of freedom were considered. Combined with the calculated results from the 1D model under braking conditions, the behavior of draft gears and brake shoes were added to the 3D model. The assessment of the curving performance of trains was focused on making comparisons between idling and braking conditions. The results indicated the following： when a train brakes on a curved track, the wheel-rail lateral force and derailment factor are greater than under idling conditions. Because the yawing movement of the wheelset is limited by brake shoes, the zone of wheel contact along the wheel tread is wider than under idling conditions. Furthermore, as the curvature becomes tighter, the traction ratio shows a nonlinear increasing trend, whether under idling or braking conditions. By increasing the brake shoe pressure, train steering becomes more difficult.
基金This project is supported by Research Foundation of Ministry of Railways of China (No.99J45-B) and National Excellent Doctor Degree Dissertation Foundation of Universities (No.200048).
文摘By using tilting carbodies, train can negotiate at a higher speed withoutreducing the passenger's ride quality. This is a good method to allow a significant increase inspeed at existing track to improve the railway transportation capability, and to enhance thecompetition ability of railways with other transportation systems. With the increase of the curvenegotiation speed, the wheel-rail lateral forces and wheel-rail wear of the tilting train willincrease. The self-steering radial bogie is an effective way to solve the problem. The dynamic modelof the tilting passenger car with self-steering bogies is established in detail, and the curvingperformance of the car is investigated.
文摘By means of ink trace visualization of the flows in conventional straight, positively curved and negatively curved cascades with tip clearance, and measurement of the aerodynamic parameters in the transverse section, and by appling topology theory, the structures on both endwalls and blade surfaces were analyzed. Compared with conventional straight cascade, blade positive curving eliminates the separation line of the upper passage vortex and leads the secondary vortex to change from close separation to open separation, while blade negative curving effects merely the positions of singular points and the intensities and scales of vortex.
文摘By means of ink trace visualization of the flows in conventional straight, positively curved and negatively curved cascades with tip clearance, and measurement of the aerodynamic parameters in transverse section, and by appling topology theory, the topological structures and vortex structure in the transverse section of a blade cascade were analyzed. Compared with conventional straight cascade, blade positive curving eliminates the separation line of the upper passage vortex, and leads the secondary vortex to change from close separation to open separation, while blade negative curving effects merely the positions of singular points and the intensities and scales of vortex.
基金the National Natural Science Foundation of China(No.51965016)the National Key Research & Development Funded Project (No. 2016YFB1200501)the Doctoral Research Start-up Funded Project (No. MY2015B009).
文摘Based on the theory of vehicle-track coupling dynamics,the coupling dynamic model of the freight car mounted with the sub-frame bogies and the numerical model of curved track were established,utilizing the fast numerical integration method,the curving performance of the vehicle was simulated to study the influence of the curve geometric parameters such as curve radius,transition curve length and superelevation of outer rail on the wheel-rail dynamic interaction.The simulation results indicate that:(1)Increasing the curve radius can decrease the wheel-rail wear,but the effect will weaken while the curve radius is greater than 800m.(2)If the transition curve length is less than 30m,vibrations will appear at the transition-circle connecting point,and the smaller the transition length,the bigger the vibrations,the worse the wheel-rail wear,but when the length is bigger than 50m,its further variation has very little effect on wheel-rail wear.(3)The superelevation of outer rail can affect the distribution and difference of the inner and outer wheel-rail forces,and too large deficient or excessive superelevation will worsen the wheel-rail wear either.However,an appropriate deficient superelevation of outer rail(e.g.<20mm)is helpful to reduce the wheel-rail wear,which is consistent with the engineering practice of settling a certain deficient superelevation value.
基金Natural Science Foundation of Henan Province of China,Grant/Award Number:232300420438Fundamental Research Funds for the Universities of Henan Province,Grant/Award Numbers:NSFRF220427,NSFRF220204+2 种基金National Natural Science foundation of China,Grant/Award Number:41972175Excellent Youth Foundation of Henan Scientific Committee,Grant/Award Number:232300421025Doctoral Foundation of Henan Polytechnic University,Grant/Award Number:B2021-78。
文摘Pores among particles provide the main space for the storage and migration of deep underground fluids(such as oil,gas,groundwater,and unconventional natural gas).The pores form a pore structure with complex morphology which is mainly dominated by the shape and distribution of particles.Therefore,the reconstruction of the pore structure or granular porous media and the evaluation of particle roundness have become an important foundation for the study of fluid flow through deep underground rock mass.This research proposes a novel approach for the multi-scale model with angular vertexes.The fractal topology theory and Voronoi space segmentation technology are combinedly used for the reconstruction of fractal granular porous media.The angular shapes are smoothed by using a modified B-spline technique and the particles with varying degrees of roundness are generated.To validate the superiority of our approach,the roundness based on the Wadell roundness calculation method is calculated and compared with the roundness obtained from particles smoothed using the vertex rounding substitution method.Results show that the roundness of particles smoothed with the modified B-spline technique closely aligns with the corresponding set rounded level(a nondimensional variable).Conversely,the vertex rounding substitution method is limited to a single dimensionally rounded radius.This innovative approach can offer a new method for the construction of granular porous media for the fluid flow study in deep underground rock mass.
基金Project supported by the Science and Technology Research Program of Chongqing Municipal Education Commission(Grant No.KJQN202504529)the General Program of Chongqing Natural Science Foundation(Grant No.CSTB2025NSCQ-GPX0833)。
文摘Kinesin-8 motors can move with a high processivity on microtubule lattices toward the plus end.After reaching the plus end,the kinesin-8 motors can pause for a long time and promote the microtubule depolymerization.Here,using atomistic molecular dynamics simulations we studied the structural changes of the kinesin-8 head in different nucleotide states bound to the straight and curved tubulins and the corresponding interactions between them.We found that the kinesin-8 head in ATP and/or ADP–Pi state has the similar strong affinity while in ADP state has the similar weak affinity to both the straight and curved tubulins,which is strongly implicated in the mechanism of the long but very different residence times of the kinesin-8 motor on the microtubule lattice and at the end.Moreover,we found that loop-2 of the kinesin-8 head bound strongly to the curved tubulin in the stable state has a large interference with its neck linker pulled in the minusended orientation.This is contrary to the case of the head bound strongly to the straight tubulin,where loop-2 has little interference with its neck linker pulled in the minus-ended orientation.The large interference can induce a larger internal force between the two heads and thus can induce the two curved tubulins bound strongly by the two heads to be more curved relative to each other.This is strongly implicated in the mechanism of the depolymerase activity of the kinesin-8motors and explains the origin of loop-2 playing a facilitating role in the depolymerase activity.
文摘Elliptic curve(EC)based cryptosystems gained more attention due to enhanced security than the existing public key cryptosystems.A substitution box(S-box)plays a vital role in securing modern symmetric key cryptosystems.However,the recently developed EC based algorithms usually trade off between computational efficiency and security,necessitating the design of a new algorithm with the desired cryptographic strength.To address these shortcomings,this paper proposes a new scheme based onMordell elliptic curve(MEC)over the complex field for generating distinct,dynamic,and highly uncorrelated S-boxes.Furthermore,we count the exact number of the obtained S-boxes,and demonstrate that the permuted version of the presented S-box is statistically optimal.The nonsingularity of the presented algorithm and the injectivity of the resultant output are explored.Rigorous theoretical analysis and experimental results demonstrate that the proposedmethod is highly effective in generating a large number of dynamic S-boxes with adequate cryptographic properties,surpassing current state-of-the-art S-box generation algorithms in terms of security.Apart fromthis,the generated S-box is benchmarked using side-channel attacks,and its performance is compared with highly nonlinear S-boxes,demonstrating comparable results.In addition,we present an application of our proposed S-box generator by incorporating it into an image encryption technique.The encrypted and decrypted images are tested by employing extensive standard security metrics,including the Number of Pixel Change Rate,the Unified Average Changing Intensity,information entropy,correlation coefficient,and histogram analysis.Moreover,the analysis is extended beyond conventional metrics to validate the new method using advanced tests,such as the NIST statistical test suite,robustness analysis,and noise and cropping attacks.Experimental outcomes show that the presented algorithm strengthens the existing encryption scheme against various well-known cryptographic attacks.
文摘This study explores the thin-layer convective solar drying of Marrubium vulgare L.leaves under conditions typical of sun-rich semi-arid climates.Drying experiments were conducted at three inlet-air temperatures(40℃,50℃,60℃)and two air velocities(1.5 and 2.5 m·s^(-1))using an indirect solar dryer with auxiliary temperature control.Moisture-ratio data were fitted with eight widely used thin-layer models and evaluated using correlation coefficient(r),root-mean-square error(RMSE),and Akaike information criterion(AIC).A complementary heattransfer analysis based on Reynolds and Prandtl numbers with appropriate Nusselt correlations was used to relate flow regime to drying performance,and an energy balance quantified the relative contributions of solar and auxiliary heat.The logarithmic model consistently achieved the lowest RMSE/AIC with r>0.99 across all conditions.Higher temperature and air velocity significantly reduced drying time during the decreasing-rate period,with no constantrate stage observed.On average,solar input supplied the large majority of the thermal demand,while the auxiliary heater compensated short irradiance drops to maintain setpoints.These findings provide a reproducible dataset and a modelling benchmark for M.vulgare leaves,and they support energy-aware design of hybrid solar dryers formedicinal plants in sun-rich regions.
基金supported by the National Research Foundation of Korea(NRF)grants(Grant Nos.RS-2020-NR049594 and RS-2022-NR071877)the Korea Agency for Infrastructure Technology Advancement under the Ministry of Land,Infrastructure and Transport(Grant No.RS-2024-00410248).
文摘Suffusion refers to the loss of fineparticles within the soil matrix without any associated volume change,induced by hydrodynamic forces.This study investigated the suffusion of sand-clay mixtures through one-dimensional soil column experiments under a stepwise increase in hydraulic gradient(i),aiming to evaluate the critical hydraulic gradient(icrit)as a function of the size ratio between sand and clay,clay type,and ionic concentration.It was found that icrit was less than 0.1 for all sand-clay mixtures examined in this study.In addition,the lower peak concentrations of filtrated clay observed in sand-illite mixtures,compared to those of sand-kaolinite mixtures at the same level of i,suggest that illite particles are more susceptible to suffusion.Overall,the observed breakthrough curves,mass fraction of filtrated clay,volume of outflow,and total injection time presented in this study highlight the importance of considering clay type,sand-to-clay size ratio,and ionic concentration when assessing the suffusion behavior of clay-containing soils under a stepwise increase in hydraulic gradient.
文摘Objectives:Uretero-enteric strictures are feared complications following cystectomy.Despite surgical advancements,particularly the rise of robot-assisted approaches,the risk factors associated with these strictures remain poorly defined.This study aimed to identify the risk factors associated with uretero-enteric anastomotic strictures after cystectomy,according to the surgical approach and type of urinary diversion(extracorporeal vs.intracorporeal).Methods:We conducted a single-center retrospective study including 340 patients who underwent cystectomy between 2016 and 2024 at Tours University Hospital.Clinical,biological,perioperative,and postoperative data were analyzed.The occurrence of a uretero-ileal anastomotic stricture was defined radiologically by a uretero-hydronephrosis≥20 mm.We constructed and analyzed a learning curve for robotic surgery with intracorporeal urinary diversion.Results:Strictures occurred in 60 patients(17.6%).On multivariable analysis,reduced preoperative glomerular filtration rate(odds ratio[OR]=1.45 per 10 mL/min decrease,95%CI[1.12-1.87],p=0.004),elevated creatinine(OR=1.30 per 10μmol/L increase,95%CI[1.05-1.61],p=0.018),prior myocardial infarction(OR=2.25,95%CI[1.10-4.62],p=0.027),and postoperative urinary tract infection(OR=3.10,95%CI[1.65-5.82],p<0.001)were independent predictors.Most strictures were left-sided.Intracorporeal robotic diversion had a higher,though non-significant,stricture rate(21.5%vs.15.2%,OR=1.52,p=0.12).Stricture rates fell markedly after 20 robotic cases per surgeon(23.8%vs.12.1%).Conclusion:Uretero-enteric strictures are multifactorial,strongly influenced by baseline renal function,cardiovascular comorbidity,and postoperative infection.Robotic intracorporeal diversion shows a learning curve effect,underlining the importance of surgical expertise and infection prevention in reducing risk.
基金supported by the National Natural Science Foundation of China(11601525)the Natural Science Foundation of Hunan Province(2024JJ5412),the Changsha Municipal Natural Science Foundation(kq2402193).
文摘In this paper,we study the nonlinear Riemann boundary value problem with square roots that is represented by a Cauchy-type integral with kernel density in variable exponent Lebesgue spaces.We discuss the odd-order zero-points distribution of the solutions and separate the single valued analytic branch of the solutions with square roots,then convert the problem to a Riemann boundary value problem in variable exponent Lebesgue spaces and discuss the singularity of solutions at individual zeros belonging to curve.We consider two types of cases those where the coefficient is Hölder and those where it is piecewise Hölder.Then we solve the Hilbert boundary value problem with square roots in variable exponent Lebesgue spaces.By discussing the distribution of the odd-order zero-points for solutions and the method of symmetric extension,we convert the Hilbert problem to a Riemann boundary value problem.The equivalence of the transformation is discussed.Finally,we get the solvable conditions and the direct expressions of the solutions in variable exponent Lebesgue spaces.
基金supported by the National Natural Science Foundation of China(Grant Nos.52379107 and 52309141).
文摘The capillary pressure curve provides fundamental insights into the dynamics of fluid-fluid displacement and phase distributions.Capillary scaling is crucial for extrapolating capillary pressure-saturation data from laboratory tests to field applications.However,the classic scaling method fails to capture the effect of wettability as the pore surface approaches neutral wetting.Here,inspired by the role of pore-filling events in controlling fluid-fluid displacement,we perform a theoretical analysis of the burst events occurring during drainage processes.We find that the median threshold capillary pressure,which corresponds to the occurrence of burst events for the median pore throat,is closely correlated with the capillary pressure curve across various contact angles.Using this concept,we propose a new scaling method for capillary pressure curves under various wetting conditions.We conduct microfluidic experiments and pore-network modeling across different contact angles,porosities,and disorders to evaluate the new scaling methods,indicating that the new scaling method performs better than the Leverett J-function as the contact angle approaches 90°.We further perform geometry analysis on the critical radius of curvature for burst events in an ideal tetrahedral arrangement and extend the new scaling method to 3D(three-dimensional)porous media.Model evaluation shows that the 3D version of the scaling method also performs well but requires fewer parameters compared to the Leverett J-function.Our work enhances the prediction and interpretation of experimental data for capillary pressure curves under various wet conditions,and more importantly,establishes a methodology that relates Darcy-scale flow behavior to pore-scale fluid displacements.
基金supported by the grants PID2020-113371RA-C22 and TED2021-130845A-C32,funded by MCIN/AEI/10.13039/501100011033.M.Marín-García,R.González-OlmosC.Gómez-Canela are members of the GESPA group(Grup d’Enginyeria i Simulacióde Processos Ambientals)at IQS-URL,which has been acknowledged as a Consolidated Research Group by the Government of Catalonia(No.2021-SGR-00321)+1 种基金In addition,M.Marín-García has been awarded a public grant for the Investigo Programme,aimed at hiring young job seekers to undertake research and innovation projects under the Recovery,Transformation,and Resilience Plan(PRTR),European Union Next Generation,for the year 2022,through the Government of Catalonia and the Spanish Ministry for Work and Social Economy(No.100045ID16)Ana Belén Cuenca for her support and expertise,which helped to confirm the proposed reaction mechanism involved in the UV photolysis of cloperastine.
文摘The increasing production and release of synthetic organic chemicals,including pharmaceuticals,into our envi-ronment has allowed these substances to accumulate in our surface water systems.Current purification technolo-gies have been unable to eliminate these pollutants,resulting in their ongoing release into aquatic ecosystems.This study focuses on cloperastine(CPS),a cough suppressant and antihistamine medication.The environmental impact of CPS usage has become a concern,mainly due to its increased detection during the COVID-19 pandemic.CPS has been found in wastewater treatment facilities,effluents from senior living residences,river waters,and sewage sludge.However,the photosensitivity of CPS and its photodegradation profile remain largely unknown.This study investigates the photodegradation process of CPS under simulated tertiary treatment conditions using UV photolysis,a method commonly applied in some wastewater treatment plants.Several transformation prod-ucts were identified,evaluating their kinetic profiles using chemometric approaches(i.e.,curve fitting and the hard-soft multivariate curve resolution-alternating least squares(HS-MCR-ALS)algorithm)and calculating the reaction quantum yield.As a result,three different transformation products have been detected and correctly identified.In addition,a comprehensive description of the kinetic pathway involved in the photodegradation process of the CPS drug has been provided,including observed kinetic rate constants.
基金financially supported by the National Key Research and Development Program of China (Nos.2023YFB3710401 and 2023YFB3710403)the State KeyLaboratory for Advanced Metals and Materials.
文摘This study investigates the effect of Ce content on the hydrogen storage properties of Ti_(0.98)Zr_(0.02)Mn_(1.5)Cr_(0.05)V_(0.43)Fe_(0.09)Ce_(x)(x=0,0.02,0.04,and 0.06,at%)alloys.Microstructural analysis of these alloys revealed dendritic microstructures without the segregation of chemical elements,with the C14 Laves phase identified as the dominant phase.After two activation cycles at 4 MPa and 293 K,the alloys exhibited excellent hydrogen absorption properties.The addition of Ce significantly improved the kinetics of the alloys.At x=0.02,the hydrogen absorption capacity reached 90%of its maximum within 137 s at 293 K.Pressure-composition-temperature curves indicated that hydrogen absorption capacity initially increased first and then decreased with increasing Ce content,reaching a maximum value of 1.85wt%at x=0.04.Thermodynamic results demonstrated that the enthalpy and entropy of hydrogen absorption followed a similar trend,which was consistent with the variation in hydrogen storage capacity.Thus,the improvement in hydrogen absorption capacity due to the addition of Ce is attributed to the increase in enthalpy.The increase of the lattice constant in the C14 Laves phase and the deoxidization effect of Ce are expected to be beneficial for the improvement of hydrogen absorption kinetics.
文摘The present study investigates the flow,heat,and mass transfer analysis in the bioconvection of nanofluid containing motile gyrotactic microorganisms through a semi-porous curved oscillatory channel with a magnetic field.These microorganisms produce density gradients by swimming,which induces macroscopic convection flows in the fluid.This procedure improves the mass and heat transfer,illustrating the interaction between biological activity and fluid dynamics.Furthermore,instead of considering traditional Fourier's and Fick's law the energy and concentration equations are developed by incorporating Cattaneo-Christov double diffusion theory.Moreover,to examine the influence of thermophoresis and Brownian diffusions in the fluid we have adopted the Buongiorno nanofluid model.Due to the oscillation of the surface of the channel,the mathematical development of the considered flow problem is obtained in the form of partial differential equations via the curvilinear coordinate system.The convergent series solution of the governing flow equations is obtained after applying the homotopy analysis method(HAM).The effects of different pertinent flow parameters on velocity,motile microorganism density distribution,concentration,pressure,temperature,and skin friction coefficient are examined and discussed in detail with the help of graphs and tables.It is observed during the current study that the density of microorganisms is enhanced for higher values of Reynolds number,Peclet number,radius of curvature variable,and Lewis number.
文摘The original online version of this article was revised:The layout update for Article 758 has impacted the page range in the published issue,but did not affect the scholarly content.To ensure consistency with the originally assigned pages(2595-2614),we will need to publish an erratum to correct the article and restore the original page range.The original article has been corrected.
文摘BACKGROUND Living donor kidney transplantation is the optimal method of long-term renal replacement therapy.Minimally invasive donor nephrectomy techniques,such as robot-assisted(RALDN)and hand-assisted(HALDN)laparoscopic procedures,are well-established in high-income countries and are being increasingly adopted worldwide.Nevertheless,no studies have reported surgical outcomes of RALDN donor nephrectomy from a United Kingdom center to date.AIM To compare surgical outcomes between RALDN and HALDN laparoscopic donor nephrectomy in a United Kingdom high-volume living kidney donor transplant program.METHODS A case-control matching analysis was performed based on the following parameters:Sex,age,body mass index,procedure laterality,number of renal arteries,and previous abdominal surgeries.Key surgical outcomes,including primary warm ischemia time,operative duration,and post-operative recovery,were evaluated.RESULTS In this cohort of 140 living donors(70 RALDN vs 70 HALDN),donor and recipient outcomes were equivalent across key metrics:Pain scores,overall complication rates,readmissions,reoperations,and creatinine levels at 30 days and 1 year.Recipient long-term renal function did not differ between groups.Operative time for RALDN decreased significantly over the study period,indicating progressive improvement along the learning curve.Although RALDN was associated with a modestly longer mean warm ischaemia time(3.53 minutes vs 2.76 minutes,P<0.001)and extended hospital stay(4.21 days vs 3.17 days,P<0.001),these did not translate into any disadvantage in clinical outcomes.CONCLUSION In this first United Kingdom comparative cohort,RALDN demonstrated excellent safety and efficacy,even in the early phase of our programme,matching the outcomes of the well-established,gold-standard HALDN approach.Moreover,the pronounced learning-curve trajectory suggests considerable potential for further improvements in robotic surgical outcomes as the programme matures.
基金supported by the National Natural Science Foundation of China (Grant No.12174455)Guangdong Basic and Applied Basic Research Foundation (Grant No.2023B1515040023)。
文摘Floquet engineering provides a powerful and flexible method for modifying the band structures of quantum materials.While circularly polarized light has been shown to convert curved nodal lines in three-dimensional semimetals into Weyl points,such a transformation is forbidden for an isolated straight nodal line.In this work,we uncover a dramatic shift in this paradigm when multiple straight nodal lines intersect.We observe that circularly polarized light not only gaps them into Weyl points but also induces unprecedented surface-state Fermi arcs that extend across the entire surface Brillouin zone and form a linked topological structure.These findings advance our fundamental understanding of light-driven transitions in topological semimetals and unveil a unique Weyl semimetal phase defined by linked Fermi arcs.We discuss potential exotic phenomena arising from this phase,applications of our predictions to spin-split antiferromagnets,and the extension of this Weyl semimetal phase to classical systems.
