Purpose: We examined the relationship between the urinary ATP level and the desire to void, voided urine volume, and urinary osmotic pressure. Materials and Methods: The subjects were 4 healthy volunteers (2 men and 2...Purpose: We examined the relationship between the urinary ATP level and the desire to void, voided urine volume, and urinary osmotic pressure. Materials and Methods: The subjects were 4 healthy volunteers (2 men and 2 women) without micturition disorders who were not taking any medications and had normal urinalysis findings. Over 2 - 3 days, they urinated into a clean cup a total of 20 times. The strength of the desire to void was classified (none, slight, moderate, or strong;scored from 1 to 4, respectively) and a voiding score was assigned at each urination, along with measurement of the voided volume, urinary ATP, urinary creatinine, and urinary osmotic pressure (one man). Results: Variation of the urinary ATP/creatinine ratio was large in both male and female subjects. The urinary ATP/creatinine ratio was lower in the 2 men compared with the 2 women. This ratio showed a significant negative correlation (R2 = 0.1577 and 0.1673, both p < 0.05) with the voided urine volume in the male subjects. However, there was no relationship between the urinary ATP/creatinine ratio and the voiding score or voided urine volume in the female subjects. Conclusions: The urinary ATP level may not be a clinically useful marker of bladder pathology. Both the present study and our previous studies identified a large sex difference in the urinary ATP/creatinine ratio, and this finding may be important when considering the causes of overactive bladder (OAB) in women. The mechanism underlying the increase in urinary ATP in women should be investigated to develop new therapies for OAB.展开更多
It has been well recognized that sand particles significantly affect the mechanical properties of reconstituted sandy clays,including the hosted clay and sand particles.However,interrelation between the permeability a...It has been well recognized that sand particles significantly affect the mechanical properties of reconstituted sandy clays,including the hosted clay and sand particles.However,interrelation between the permeability and compressibility of reconstituted sandy clays by considering the structural effects of sand particles is still rarely reported.For this,a series of consolidation-permeability coefficient tests were conducted on reconstituted sandy clays with different sand fractions(ψ_(ss)),initial void ratio of hosted clays(e_(c0))and void ratio at liquid limit of hosted clays(e_(cL)).The roles of ψ_(ss) in both the relationships of permeability coefficient of hosted clay(k_(v-hosted clay))versus effective vertical stress(σ'_(v))and void ratio of hosted clay(e_(c-hosted clay))versus σ'_(v) were analyzed.The results show that the permeability coefficient of reconstituted sandy clays(k_(v))is dominated by hosted clay(k_(v)=k_(v-hosted clay)).Both ψ_(ss) and σ'_(v) affect the k_(v) of sandy clays by changing the e_(c-hosted clay) at any given σ'_(v).Due to the partial contacts and densified clay bridges between the sand particles(i.e.structure effects),the e_(c-hosted clay) in sandy clays is higher than that in clays at the same σ'_(v)v.The k_(v)-e_(c-hosted clay) relationship of sandy clays is independent of σ'_(v) and ψ_(ss)but is a function of e_(cL).The types of hosted clays affect the k_(v) of sandy clays by changing the e_(cL).Based on the relationship between permeability coefficient and void ratio for the reconstituted clays,an empirical method for determining the k_(v) is proposed and validated for sandy clays.The predicted values are almost consistent with the measured values with k_(v-predicted)=k_(v-measured)=0.6-2.5.展开更多
High-entropy alloys(HEAs)exhibit the excellent elevated-temperature performance and irradiation resistance due to the important core effect of serious lattice distortion for impeding dislocation motion,as candidate ma...High-entropy alloys(HEAs)exhibit the excellent elevated-temperature performance and irradiation resistance due to the important core effect of serious lattice distortion for impeding dislocation motion,as candidate materials for nuclear applications.Despite the growth of the nuclear power sector,the effects of high-temperature and high-dose irradiation-induced voids on the mechanical properties of HEA in higher power nuclear reactors remain insufficiently researched,hindering its industrial application.In this study,we establish a consistent parameterization crystal plastic constitutive model for the hardening and creep behaviors of HEA,incorporating the spatial distribution of void size and shape effects,in contrast to traditional creep models that rely on temperature-related fitting parameters of the phenomenological power law equation.The model matches well with experimental data at different temperatures and irradiation doses,demonstrating its robustness.The effects of irradiation dose,temperature,and degree of lattice distortion on irradiation hardening and creep behavior of void-containing HEA are investigated.The results indicate that HEA with high lattice distortion exhibits better creep resistance under higher stress loads.The yield stress of irradiated HEA increases with increasing irradiation dose and temperature.The creep resistance increases with increasing irradiation dose and decreases with increasing irradiation temperature.The increase in irradiation dose causes a specific morphological transformation from spherical to cubic voids.The modeling and results could provide an effective theoretical way for tuning the yield strength and alloy design in advanced HEAs to meet irradiation properties.展开更多
Objective To determine the prevalence,distribution,and associated clinical factors of chronic neuropathic cancer pain(CNCP)among outpatients with chronic cancer pain(CCP)and to inform improved recognition and manageme...Objective To determine the prevalence,distribution,and associated clinical factors of chronic neuropathic cancer pain(CNCP)among outpatients with chronic cancer pain(CCP)and to inform improved recognition and management.Methods In this cross-sectional study,consecutive outpatients with CCP diagnosed according to the International Association for the Study of Pain(IASP)criteria were recruited from the pain clinic at Peking Union Medical College Hospital between June and October 2025.CNCP was diagnosed based on the Neuropathic Pain Special Interest Group(NeuPSIG)criteria.Patients were classified into the CNCP group if they met at least one of the four NeuPSIG criteria,regardless of coexisting visceral or bone pain.Demographic,oncologic,and pain-related data were collected through standardized interviews.Between-group differences in baseline characteristics were assessed using absolute standardized differences and Chi-square or t-tests.Logistic regression analyses were conducted to identify clinical factors associated with CNCP.Results Of 138 eligible patients with CCP,85(61.6%)were classified into the CNCP group and 53(38.4%)into the non-CNCP group.Multivariable logistic regression analysis revealed that bone metastasis(adjusted OR=2.316,95%CI:1.074-5.178,P=0.032),radiotherapy(adjusted OR=2.489,95%CI:1.119-5.803,P=0.025),and voiding dysfunction(adjusted OR=5.470,95%CI:2.150-16.396,P<0.001)were independently associated with CNCP.Pancreatic cancer was inversely associated with CNCP(OR=0.371,P=0.031).Only 5(3.6%)patients in the CNCP group received neuropathic pain-specific interventions,indicating a predominant reliance on single-modality pain management.Conclusions CNCP was present in nearly two-thirds of outpatients with CCP.The identified associations with bone metastasis,radiotherapy,and voiding dysfunction may aid in the early recognition of neuropathic pain components and support the adoption of mechanism-based multimodal pain management strategies.展开更多
A ground girder is laid on the preprocessed subgrade by gravity compaction and integrally uniformly supported by subgrade in maglev transit.The settlement of the maglev subgrade inevitably affects the vibration state ...A ground girder is laid on the preprocessed subgrade by gravity compaction and integrally uniformly supported by subgrade in maglev transit.The settlement of the maglev subgrade inevitably affects the vibration state of the medium and low speed maglev coupled system by the additional deformation of the maglev track.This study investigated the dynamic properties of the coupled vibration system affected by the subgrade settlement.First,a theoretical coupled vibration model of a maglev train-track-ground girder system with uneven subgrade settlement was proposed and verified.Then,the effect mechanism of the coupled system caused by the uneven subgrade settlement was explored.Finally,settlement types and subgrade support voiding were examined.The analysis showed that the uneven subgrade settlement considerably increased the dynamic responses of the levitation control system and maglev vehicle while having a minor influence on those of the track-ground girder.The influence of a single ground girder settling was the strongest,and adjacent sides’settling of two ground girders was the weakest for the vibration of a maglev train.An extremely large uneven settlement exceeding 6 mm led to active levitation control system instability.The subgrade support voiding enlarged the vehicle-induced vibration of the track ground girder.展开更多
Flip-chip technology is widely used in integrated circuit(IC)packaging.Molded underfill transfer molding is the most common process for these products,as the chip and solder bumps must be protected by the encapsulatin...Flip-chip technology is widely used in integrated circuit(IC)packaging.Molded underfill transfer molding is the most common process for these products,as the chip and solder bumps must be protected by the encapsulating material to ensure good reliability.Flow-front merging usually occurs during the molding process,and air is then trapped under the chip,which can form voids in the molded product.The void under the chip may cause stability and reliability problems.However,the flow process is unobservable during the transfer molding process.The engineer can only check for voids in the molded product after the process is complete.Previous studies have used fluid visualization experiments and developed computational fluid dynamics simulation tools to investigate this issue.However,a critical gap remains in establishing a comprehensive three-dimensional model that integrates two-phase flow,accurate venting settings,and fluid surface tension for molded underfill void evaluation—validated by experimental fluid visualization.This study aims to address this gap in the existing literature.In this study,a fluid visualization experiment was designed to simulate the transfer molding process,allowing for the observation of flow-front merging and void formation behaviors.For comparison,a three-dimensional mold flow analysis was also performed.It was found that the numerical simulation of the trapped air compression process under the chip was more accurate when considering the capillary force.The effect of design factors is evaluated in this paper.The results show that the most important factors for void size are fluid viscosity,the gap height under the chip,transfer time,contact angle between the fluid and the contact surfaces,and transfer pressure.Specifically,a smaller gap height beneath the chip aggravates void formation,while lower viscosity,extended transfer time,reduced contact angle,and increased transfer pressure are effective in minimizing void size.The overall results of this study will be useful for product and process design in selecting appropriate solutions for IC packaging,particularly in the development of void-free molded-underfill flip-chip packages.These findings support the optimization of industrial packaging processes in semiconductor manufacturing by guiding material selection and process parameters,ultimately enhancing package reliability and yield.展开更多
Renewable energy storage technologies are critical for transitioning to sustainable energy systems,with salt caverns playing a significant role in large-scale solutions.In water-soluble mining of low-grade salt format...Renewable energy storage technologies are critical for transitioning to sustainable energy systems,with salt caverns playing a significant role in large-scale solutions.In water-soluble mining of low-grade salt formations,insoluble impurities and interlayers detach during salt dissolution and accumulate as sediment at the cavern base,thereby reducing the storage capacity and economic viability of salt cavern gas storage(SCGS).This study investigates sediment formation mechanisms,void distribution,and voidage in the Huai'an low-grade salt mine,introducing a novel self-developed physical simulation device for two butted-well horizontal(TWH)caverns that replicates compressed air injection and brine discharge.Experiments comparing“one injection and one discharge”and“two injections and one discharge”modes revealed that(1)compressed air effectively displaces brine from sediment voids,(2)a 0.5 MPa injection pressure corresponds to a 10.3 MPa operational lower limit in practice,aligning with field data,and(3)sediment voidage is approximately 46%,validated via air-brine interface theory.The“two injections and one discharge”mode outperformed in both discharge volume and rate.Additionally,a mathematical model for brine displacement via compressed air was established.These results provide foundational insights for optimizing compressed air energy storage(CAES)in low-grade salt mines,advancing their role in renewable energy integration.展开更多
Nano-twinned copper(nt-Cu),with a preferred orientation,is highly promising as interconnect materials in high-density advanced packaging due to its considerable mechanical strength,excellent electrical conductivity,an...Nano-twinned copper(nt-Cu),with a preferred orientation,is highly promising as interconnect materials in high-density advanced packaging due to its considerable mechanical strength,excellent electrical conductivity,and resistance to thermal migration.However,its application is impeded by sulfur-containing byproducts from the electroplating process,exacerbating the formation of Kirkendall voids within solder joints during thermal aging.Herein,through the incorporation of Zinc(Zn)into the nt-Cu layer,we develop a nt-Cu/Zn composite structure.Our findings provide the first definitive confirmation of the mechanism by which sulfur atoms migrate to the Cu_(3)Sn/nt-Cu interface through interstitial diffusion,thereby reducing the activation energy for vacancy formation.We further demonstrate that Zn effectively an-choring sulfur atoms,forming ZnS within the nt-Cu layer during heat treatment,which increases the vacancy formation energy and inhibits the development of Kirkendall voids.Remarkably,no Kirkendall voids are observed in the modified interconnects even after prolonged aging at 150℃ for 1000 h.The nt-Cu/Zn composite metallization layers significantly decrease the growth rate of interfacial intermetallic compounds by 33.6% and enhance the shear strength of solder interconnections to 228.9%.This research underscores the potential of nt-Cu in advanced electronic packaging,offering new pathways for improving the power density and reliability of electronic devices.展开更多
Voids play an important role in the fatigue behaviour of polycrystal materials.In this paper,the effects of three factors affecting the stress concentration factors(SCFs)near voids,i.e.,size,depth,and applied load,are...Voids play an important role in the fatigue behaviour of polycrystal materials.In this paper,the effects of three factors affecting the stress concentration factors(SCFs)near voids,i.e.,size,depth,and applied load,are investigated by employing crystal plasticity constitutive models in polycrystal bulks.The results indicate that SCF is dominated by the void size,while void depth and stress level play secondary roles.The SCF fluctuates by the orientation differences among grains and increases with increasing the size of the void.Finally,based on sensitivity examination of orientations and configurations of grains sur-rounding the void,an empirical multivariable-coupled formula is proposed to assess SCF near voids considering anisotropy,and the presented model is in good agreement with the simulation results.展开更多
Compaction grouting is primarily applied based on empiricism,and it is challenging to quantify its densification effect.To address this issue,five sets of laboratory model tests on ideal compaction grouting were condu...Compaction grouting is primarily applied based on empiricism,and it is challenging to quantify its densification effect.To address this issue,five sets of laboratory model tests on ideal compaction grouting were conducted,with varying pressures from 400 kPa to 800 kPa,to quantitatively evaluate the densification effect in unsaturated soils.The response of surrounding soil during compaction grouting was monitored.The changes in dry density and void ratio induced by compaction grouting were obtained by monitoring volumetric water content to determine compaction efficiency.In addition,a model was developed and validated to predict the effective compaction range.The results show that soil dry density increased rapidly during compaction grouting before being stabilized at a consistent level.As expected,it is positively correlated with grouting pressures(GPs)and negatively correlated with the distance from the injection point.At higher GPs,the difference in densification effect around the injection point after compaction grouting was significant.Interestingly,variations in ultimate dry density and peak earth pressures perpendicular to the injection direction exhibited axisymmetric behavior around the injection point when comparing the dry density and earth pressure results.Furthermore,soil densification resulted in a decrease in suction.However,no significant effect of GP on suction at different soil positions was observed.Moreover,compaction efficiency decreased with increasing distance from the injection point,showing a strong linear relationship.In addition,the model results for the effective compaction range were basically consistent with the extrapolated values from the experimental results.展开更多
Large-grain REBa_(2)Cu_(3)O_(7-δ)(REBCO,RE=rare earth)bulk superconductors offer promising magnetic field trapping capabilities due to their high critical current density,making them ideal for many important applicat...Large-grain REBa_(2)Cu_(3)O_(7-δ)(REBCO,RE=rare earth)bulk superconductors offer promising magnetic field trapping capabilities due to their high critical current density,making them ideal for many important applications such as trapped field magnets.However,for such large-grain superconductor bulks,there are lots of voids and cracks forming during the process of melting preparation,and some of them can be up to hundreds of microns or even millimeters in size.Consequently,these larger size voids/cracks pose a great threat to the strength of the bulks due to the inherent brittleness of superconductor REBCO materials.In order to ensure the operational safety of related superconducting devices with bulk superconductors,it is firstly important to accurately detect these voids/cracks in them.In this paper,we proposed a method for quantitatively evaluating multiple voids/cracks in bulk superconductors through the magnetic field and displacement response signals at superconductor bulk surface.The proposed method utilizes a damage index constructed from the magnetic field signals and displacement responses to identify the number and preliminary location of multiple defects.By dividing the detection area into subdomains and combining the magnetic field signals with displacement responses within each subdomain,a particle swarm algorithm was employed to evaluate the location and size parameters of the defects.In contrast to other evaluation methods using only magnetic field or displacement response signals,the combined evaluation method using both signals can identify the number of cracks effectively.Numerical studies demonstrate that the morphology of voids and cracks reconstructed using the proposed algorithm ideally matches real defects and is applicable to cases where voids and cracks coexist.This study provides a theoretical basis for the quantitative detection of voids/cracks in bulk superconductors.展开更多
This work investigates the dynamic response of a monocrystalline nickel-titanium(NiTi)alloy at the atomic scale.The results deduced from non-equilibrium molecular dynamics modeling demonstrate that no shear deformatio...This work investigates the dynamic response of a monocrystalline nickel-titanium(NiTi)alloy at the atomic scale.The results deduced from non-equilibrium molecular dynamics modeling demonstrate that no shear deformation band(SDB)appears in the sample at an impact velocity of less than 0.75 km/s.As this velocity increases,shear deformations become pronouncedly localized,and the average spacing between SDBs decreases until it stabilizes.Combining shear stress and particle velocity profiles,the survival of SDBs is found to be closely associated with plastic deformation.The dislocations clustering around SDBs predominantly exhibit 100 partial dislocations,whereas 1/2111 full dislocations are dominant in those regions without SDBs.Void nucleation always occurs on SDBs.Subsequently,void growth promotes a change in the SDB distribution characteristic.For the case without SDB,voids are randomly nucleated,and the void growth exhibits a non-uniform manner.Thus,there is an interaction between shear localization and void evolution in the NiTi alloy subjected to intensive loading.This study is expected to provide in-depth insights into the microscopic mechanism of NiTi dynamic damage.展开更多
Kirkendall voids(KVs)at the Cu/Sn interface are a typical failure in integrated circuits,leading to solder joint cracking and electrical disconnection.Although the formation of KVs has been attributed to the differenc...Kirkendall voids(KVs)at the Cu/Sn interface are a typical failure in integrated circuits,leading to solder joint cracking and electrical disconnection.Although the formation of KVs has been attributed to the difference in atomic diffusion rates at the Cu/Sn interface,the role of Cu intrinsic"quality"parameters(crystal defects)in this process remains unclear.This work systematically investigated the effects of Cu crystal defects on KVs:Cu substrates with different lattice defects and grain boundaries were prepared using proprietary electrodeposition additives,and the number of defects was quantitatively characterized by micro-strain,geometric dislocation density,and geometric phase analysis.The thermal aging experiments further showed that the formation of intermetallic compounds and KVs was related to crystal defect energy.When the grain boundary energy was higher than the lattice energy,the additional driving force resulted in short-circuit diffusion,causing local Cu depletion and voids.The lowcrystal-defect samples maintained the local Cu/Sn interdiffusion equilibrium,resulting in fewer voids after 1000 h.This study emphasizes that regulating the crystal defects can reduce KVs and provides a new insight for improving the integrated solder joint's reliability.展开更多
With the ever-increasing energy density requirements for sulfide-based all-solid-state batteries,lithium metal is regarded as an ideal candidate for anode materials.However,the dynamic degradation of solidsolid contac...With the ever-increasing energy density requirements for sulfide-based all-solid-state batteries,lithium metal is regarded as an ideal candidate for anode materials.However,the dynamic degradation of solidsolid contact between lithium anode and solid electrolyte remains a major challenge for the application of all-solid-state lithium metal batteries(ASSLMBs).The poor solid-solid contact problem is caused by the continuous accumulation of lithium voids,which results from the limited diffusion rate of lithium in the bulk phase.In this study,we design a three-dimensional(3D)lithiophilic graphitized carbon nanotubebased(LNT)interlayer to address interfacial issues.The interlayers effectively regulate lithium stripping and suppress the growth of lithium voids via improved lithium diffusion,leading to a conformal interface during continuous cycling.The lithium metal anode with the interlayer delivers an areal capacity of 12.96 mA h cm^(-2),and when paired with a LiNi_(0.9)Co_(0.05)Mn_(0.05)O_(2)(NCM9)cathode,the battery retains over 91%capacity retention after 100 cycles at room temperature.This work provides an effective strategy for interface stabilization in high-capacity and long-life ASSLMBs.展开更多
Nickel-based alloys are the primary structural materials in steam generators of high-temperature gas reactors.To understand the irradiation effect of nickel-based alloys,it is necessary to examine dislocation movement...Nickel-based alloys are the primary structural materials in steam generators of high-temperature gas reactors.To understand the irradiation effect of nickel-based alloys,it is necessary to examine dislocation movement and its interaction with irradiation defects at the microscale.Hardening due to voids and Ni_(3)Al precipitates may significantly impact irradiation damage in nickel-based alloys.This paper employs the molecular dynamics method to analyze the interaction between edge dislocations and irradiation defects(void and Ni_(3)Al precipitates)in face-centered cubic nickel.The effects of temperature and defect size on the interaction are also explored.The results show that the interaction process of the edge dislocation and irradiation defects can be divided into four stages:dislocation free slip,dislocation attracted,dislocation pinned,and dislocation unpinned.Interaction modes include the formation of stair-rod dislocations and the climbing of extended dislocation bundles for voids,as well as the generation of stair-rod dislocation and dislocation shear for precipitates.Besides,the interactions of edge dislocations with voids and Ni_(3)Al precipitates are strongly influenced by temperature and defect size.展开更多
The freeze-thaw(FT)behavior of porous materials(PMs)involves the coupling of the thermo-hydromechanical(THM)processes and is significantly influenced by the microstructure.However,modeling FT in unsaturated PMs remain...The freeze-thaw(FT)behavior of porous materials(PMs)involves the coupling of the thermo-hydromechanical(THM)processes and is significantly influenced by the microstructure.However,modeling FT in unsaturated PMs remains an open issue,and the influence of microstructure is not yet fully understood.To address these challenges,we propose a THM model for FT in PMs that considers microstructure and variable air content.In this work,a non-equilibrium thermodynamic approach is proposed to capture ice formation/melting,the microstructure is accounted for utilizing micromechanics,and the FT processes in air-entrained PMs are formulated within the proposed THM model.This model incorporates variable air void characteristics,e.g.air content,spacing factor,specific surface area,and supercooled water-filled regimes,and distinguishes the roles of air voids between freezing and thawing.The FT behaviors,including deformation,ice formation/melting,spacing factor,and pore water pressure evolutions,are focused.Comparisons with experimental results,confirm the capability of the present model.The results demonstrate the effects of variable air voids on the FT behavior of air-entrained PMs.The findings reveal that assuming fixed air void characteristics can lead to underestimation of pore pressure and deformation,particularly at low air content.Additionally,air voids act as cryo-pumps during freezing and when the cooling temperature stabilizes.During thawing,air voids supply gas to the melting sites(i.e.“gas escape”),preventing further significant deformation reduction.These results can provide novel insights for understanding the frost damage of PMs.展开更多
Dear Editor,Primary bladder neck obstruction(PBNO)affects approximately 28%–54%of men[1].Its etiology remains unclear.Symptoms of PBNO present as voiding(e.g.,decreased force of stream,hesitancy,intermittent stream,a...Dear Editor,Primary bladder neck obstruction(PBNO)affects approximately 28%–54%of men[1].Its etiology remains unclear.Symptoms of PBNO present as voiding(e.g.,decreased force of stream,hesitancy,intermittent stream,and incomplete emptying),storage(e.g.,frequency,urgency,urge incontinence,and nocturia),or a combination of both[2].Untreated PBNO can lead to bladder dysfunction,bladder diverticula,hydronephrosis,and impaired renal function[3].展开更多
Detecting internal defects,particularly voids behind linings,is critical for ensuring the structural integrity of aging high-speed rail(HSR)tunnel networks.While ground-penetrating radar(GPR)is widely employed,systema...Detecting internal defects,particularly voids behind linings,is critical for ensuring the structural integrity of aging high-speed rail(HSR)tunnel networks.While ground-penetrating radar(GPR)is widely employed,systematic quantification of performance boundaries for air-coupled(A-CGPR)and ground-coupled(G-CGPR)systems within the complex electromagnetic environment of multilayer reinforced HSR tunnels remains limited.This study establishes physics-based quantitative performance limits for A-CGPR and G-CGPR through rigorously validated GPRMax finite-difference time-domain(FDTD)simulations and comprehensive field validation over a 300 m operational HSR tunnel section.Key performance metrics were quantified as functions of:(a)detection distance(A-CGPR:2.0–4.5 m;G-CGPR:≤0.1 m),(b)antenna frequency(A-CGPR:300 MHz;G-CGPR:400/900 MHz),(c)reinforcement configuration(unreinforced,single-layer,multilayer rebar),and(d)void geometry(axial length:0.1–1.0 m;radial depth:0.1–0.5 m).Key findings demonstrate:a.A-CGPR(300 MHz):Reliably detects axial voids≥0.3 m at distances≤3 m in minimally reinforced(single-layer rebar)linings(field R2=0.89).Performance degrades significantly at distances>3 m(>60%signal attenuation at 4.5 m)or under multilayer rebar interference,causing 25%–40%accuracy loss for voids<0.3 m.Optimal distance:2.0–2.5 m.b.G-CGPR(900 MHz):Achieves<5%size measurement error for axial voids≥0.1 m and radial voids≥0.2 m in unreinforced linings.Resolution degrades under multilayer reinforcement due to severe signal attenuation,increasing axial void detection error to 10%–20%for voids≥0.3 m and constraining radial size measurement.c.Synergistic Framework:A hybrid inspection protocol is proposed,integrating A-CGPR(20 km/h)for rapid large-area screening and targeted G-CGPR(3 km/h)for high-resolution verification of identified anomalies.This framework enhances NDT efficiency while reducing estimated lifecycle inspection costs by 34%compared to G-CGPR alone.This research provides the first physics-derived quantitative detection thresholds for A-CGPR and G-CGPR in multi-rebar HSR tunnels,validated through field-correlated simulations.Future work will focus on multi-frequency antenna arrays and deep learning algorithms to mitigate reinforcement interference.The established performance boundaries and hybrid framework offer critical guidance for optimizing tunnel lining inspection strategies in extensive HSR networks.展开更多
Multilayered Ti-Al based intermetallic sheets were fabricated by sintering alternately layered titanium and aluminum foils.The microstructure and phase formation of the obtained sheets under different sintering condit...Multilayered Ti-Al based intermetallic sheets were fabricated by sintering alternately layered titanium and aluminum foils.The microstructure and phase formation of the obtained sheets under different sintering conditions were evaluated by various techniques.The results reveal that when the sintering temperature is above the melting point of aluminum,the self-propagating high-temperature synthesis reaction occurs between Ti and Al,and forms various phases of Ti-based solid solutions including α-Ti Ti3Al,TiAl,TiAl2 and α-Ti including TiAl3,etc.When the sintering time increased,Ti-based solid solution,TiAl2 and TiAl3 disappeared gradually,and the sheet containing Ti3Al and TiAl phases in a multilayered structure formed finally.A lot of voids were also observed in the sintered structures,which were caused by the melting Al,Kirkendall effect and the difference of molar volumes between reactants and products.The voids were eliminated and a dense sample was obtained by the following hot press.展开更多
The bonding interface characteristic and shear strength of diffusion bonded Ti-17 titanium alloy at different bonding time were investigated. The results show that the average size of voids decreases while the amount ...The bonding interface characteristic and shear strength of diffusion bonded Ti-17 titanium alloy at different bonding time were investigated. The results show that the average size of voids decreases while the amount of voids decreases after increasing to the maximum value with the increasing bonding time. The irregular void with a scraggly edge tends to an ellipse void with smooth surface and then changes to a tiny void with round shape. The grains across bonding interface occur at bonding time of 60 min. The shear strength of bond increases with increasing bonding time, and the highest shear strength of bond is 887.4 MPa at 60 min. The contribution of plastic deformation on the void closure and the increase of shear strength is significant even though the action time of plastic deformation is short.展开更多
文摘Purpose: We examined the relationship between the urinary ATP level and the desire to void, voided urine volume, and urinary osmotic pressure. Materials and Methods: The subjects were 4 healthy volunteers (2 men and 2 women) without micturition disorders who were not taking any medications and had normal urinalysis findings. Over 2 - 3 days, they urinated into a clean cup a total of 20 times. The strength of the desire to void was classified (none, slight, moderate, or strong;scored from 1 to 4, respectively) and a voiding score was assigned at each urination, along with measurement of the voided volume, urinary ATP, urinary creatinine, and urinary osmotic pressure (one man). Results: Variation of the urinary ATP/creatinine ratio was large in both male and female subjects. The urinary ATP/creatinine ratio was lower in the 2 men compared with the 2 women. This ratio showed a significant negative correlation (R2 = 0.1577 and 0.1673, both p < 0.05) with the voided urine volume in the male subjects. However, there was no relationship between the urinary ATP/creatinine ratio and the voiding score or voided urine volume in the female subjects. Conclusions: The urinary ATP level may not be a clinically useful marker of bladder pathology. Both the present study and our previous studies identified a large sex difference in the urinary ATP/creatinine ratio, and this finding may be important when considering the causes of overactive bladder (OAB) in women. The mechanism underlying the increase in urinary ATP in women should be investigated to develop new therapies for OAB.
基金supported by the National Natural Science Foundation of China (Grant Nos.52278334 and 4197724)Fundamental Research Funds for the Central Universities (Grant No.2242024k30066).
文摘It has been well recognized that sand particles significantly affect the mechanical properties of reconstituted sandy clays,including the hosted clay and sand particles.However,interrelation between the permeability and compressibility of reconstituted sandy clays by considering the structural effects of sand particles is still rarely reported.For this,a series of consolidation-permeability coefficient tests were conducted on reconstituted sandy clays with different sand fractions(ψ_(ss)),initial void ratio of hosted clays(e_(c0))and void ratio at liquid limit of hosted clays(e_(cL)).The roles of ψ_(ss) in both the relationships of permeability coefficient of hosted clay(k_(v-hosted clay))versus effective vertical stress(σ'_(v))and void ratio of hosted clay(e_(c-hosted clay))versus σ'_(v) were analyzed.The results show that the permeability coefficient of reconstituted sandy clays(k_(v))is dominated by hosted clay(k_(v)=k_(v-hosted clay)).Both ψ_(ss) and σ'_(v) affect the k_(v) of sandy clays by changing the e_(c-hosted clay) at any given σ'_(v).Due to the partial contacts and densified clay bridges between the sand particles(i.e.structure effects),the e_(c-hosted clay) in sandy clays is higher than that in clays at the same σ'_(v)v.The k_(v)-e_(c-hosted clay) relationship of sandy clays is independent of σ'_(v) and ψ_(ss)but is a function of e_(cL).The types of hosted clays affect the k_(v) of sandy clays by changing the e_(cL).Based on the relationship between permeability coefficient and void ratio for the reconstituted clays,an empirical method for determining the k_(v) is proposed and validated for sandy clays.The predicted values are almost consistent with the measured values with k_(v-predicted)=k_(v-measured)=0.6-2.5.
基金support from the National Natural Science Foundation of China(Nos.12302083,U2267252,12372069,and 12172123)the China Postdoctoral Science Foundation(Nos.2023M731061 and BX20230109)+1 种基金the Natural Science Foundation of Hunan Province(No.2022JJ20001)the Hunan Provincial Innovation Foundation for Postgraduate(No.CX20230420).
文摘High-entropy alloys(HEAs)exhibit the excellent elevated-temperature performance and irradiation resistance due to the important core effect of serious lattice distortion for impeding dislocation motion,as candidate materials for nuclear applications.Despite the growth of the nuclear power sector,the effects of high-temperature and high-dose irradiation-induced voids on the mechanical properties of HEA in higher power nuclear reactors remain insufficiently researched,hindering its industrial application.In this study,we establish a consistent parameterization crystal plastic constitutive model for the hardening and creep behaviors of HEA,incorporating the spatial distribution of void size and shape effects,in contrast to traditional creep models that rely on temperature-related fitting parameters of the phenomenological power law equation.The model matches well with experimental data at different temperatures and irradiation doses,demonstrating its robustness.The effects of irradiation dose,temperature,and degree of lattice distortion on irradiation hardening and creep behavior of void-containing HEA are investigated.The results indicate that HEA with high lattice distortion exhibits better creep resistance under higher stress loads.The yield stress of irradiated HEA increases with increasing irradiation dose and temperature.The creep resistance increases with increasing irradiation dose and decreases with increasing irradiation temperature.The increase in irradiation dose causes a specific morphological transformation from spherical to cubic voids.The modeling and results could provide an effective theoretical way for tuning the yield strength and alloy design in advanced HEAs to meet irradiation properties.
文摘Objective To determine the prevalence,distribution,and associated clinical factors of chronic neuropathic cancer pain(CNCP)among outpatients with chronic cancer pain(CCP)and to inform improved recognition and management.Methods In this cross-sectional study,consecutive outpatients with CCP diagnosed according to the International Association for the Study of Pain(IASP)criteria were recruited from the pain clinic at Peking Union Medical College Hospital between June and October 2025.CNCP was diagnosed based on the Neuropathic Pain Special Interest Group(NeuPSIG)criteria.Patients were classified into the CNCP group if they met at least one of the four NeuPSIG criteria,regardless of coexisting visceral or bone pain.Demographic,oncologic,and pain-related data were collected through standardized interviews.Between-group differences in baseline characteristics were assessed using absolute standardized differences and Chi-square or t-tests.Logistic regression analyses were conducted to identify clinical factors associated with CNCP.Results Of 138 eligible patients with CCP,85(61.6%)were classified into the CNCP group and 53(38.4%)into the non-CNCP group.Multivariable logistic regression analysis revealed that bone metastasis(adjusted OR=2.316,95%CI:1.074-5.178,P=0.032),radiotherapy(adjusted OR=2.489,95%CI:1.119-5.803,P=0.025),and voiding dysfunction(adjusted OR=5.470,95%CI:2.150-16.396,P<0.001)were independently associated with CNCP.Pancreatic cancer was inversely associated with CNCP(OR=0.371,P=0.031).Only 5(3.6%)patients in the CNCP group received neuropathic pain-specific interventions,indicating a predominant reliance on single-modality pain management.Conclusions CNCP was present in nearly two-thirds of outpatients with CCP.The identified associations with bone metastasis,radiotherapy,and voiding dysfunction may aid in the early recognition of neuropathic pain components and support the adoption of mechanism-based multimodal pain management strategies.
基金National Natural Science Foundation of China under Grant Nos.52478467and 52108417Guangdong Basic and Applied Basic Research Foundation under Grant No.2024A1515012569the Natural Science Basic Research Program of Shaanxi under Grant No.2021JQ-101。
文摘A ground girder is laid on the preprocessed subgrade by gravity compaction and integrally uniformly supported by subgrade in maglev transit.The settlement of the maglev subgrade inevitably affects the vibration state of the medium and low speed maglev coupled system by the additional deformation of the maglev track.This study investigated the dynamic properties of the coupled vibration system affected by the subgrade settlement.First,a theoretical coupled vibration model of a maglev train-track-ground girder system with uneven subgrade settlement was proposed and verified.Then,the effect mechanism of the coupled system caused by the uneven subgrade settlement was explored.Finally,settlement types and subgrade support voiding were examined.The analysis showed that the uneven subgrade settlement considerably increased the dynamic responses of the levitation control system and maglev vehicle while having a minor influence on those of the track-ground girder.The influence of a single ground girder settling was the strongest,and adjacent sides’settling of two ground girders was the weakest for the vibration of a maglev train.An extremely large uneven settlement exceeding 6 mm led to active levitation control system instability.The subgrade support voiding enlarged the vehicle-induced vibration of the track ground girder.
文摘Flip-chip technology is widely used in integrated circuit(IC)packaging.Molded underfill transfer molding is the most common process for these products,as the chip and solder bumps must be protected by the encapsulating material to ensure good reliability.Flow-front merging usually occurs during the molding process,and air is then trapped under the chip,which can form voids in the molded product.The void under the chip may cause stability and reliability problems.However,the flow process is unobservable during the transfer molding process.The engineer can only check for voids in the molded product after the process is complete.Previous studies have used fluid visualization experiments and developed computational fluid dynamics simulation tools to investigate this issue.However,a critical gap remains in establishing a comprehensive three-dimensional model that integrates two-phase flow,accurate venting settings,and fluid surface tension for molded underfill void evaluation—validated by experimental fluid visualization.This study aims to address this gap in the existing literature.In this study,a fluid visualization experiment was designed to simulate the transfer molding process,allowing for the observation of flow-front merging and void formation behaviors.For comparison,a three-dimensional mold flow analysis was also performed.It was found that the numerical simulation of the trapped air compression process under the chip was more accurate when considering the capillary force.The effect of design factors is evaluated in this paper.The results show that the most important factors for void size are fluid viscosity,the gap height under the chip,transfer time,contact angle between the fluid and the contact surfaces,and transfer pressure.Specifically,a smaller gap height beneath the chip aggravates void formation,while lower viscosity,extended transfer time,reduced contact angle,and increased transfer pressure are effective in minimizing void size.The overall results of this study will be useful for product and process design in selecting appropriate solutions for IC packaging,particularly in the development of void-free molded-underfill flip-chip packages.These findings support the optimization of industrial packaging processes in semiconductor manufacturing by guiding material selection and process parameters,ultimately enhancing package reliability and yield.
基金financial support from the National Key Research and Development Program of China(No.2024YFB4007100)the Basic ForwardLooking Project of the Sinopec Science and Technology Department,“Research on the Long-Term Sealing Mechanism of Multi-layer Salt Cavern Hydrogen Storage”(No.P24197-4)。
文摘Renewable energy storage technologies are critical for transitioning to sustainable energy systems,with salt caverns playing a significant role in large-scale solutions.In water-soluble mining of low-grade salt formations,insoluble impurities and interlayers detach during salt dissolution and accumulate as sediment at the cavern base,thereby reducing the storage capacity and economic viability of salt cavern gas storage(SCGS).This study investigates sediment formation mechanisms,void distribution,and voidage in the Huai'an low-grade salt mine,introducing a novel self-developed physical simulation device for two butted-well horizontal(TWH)caverns that replicates compressed air injection and brine discharge.Experiments comparing“one injection and one discharge”and“two injections and one discharge”modes revealed that(1)compressed air effectively displaces brine from sediment voids,(2)a 0.5 MPa injection pressure corresponds to a 10.3 MPa operational lower limit in practice,aligning with field data,and(3)sediment voidage is approximately 46%,validated via air-brine interface theory.The“two injections and one discharge”mode outperformed in both discharge volume and rate.Additionally,a mathematical model for brine displacement via compressed air was established.These results provide foundational insights for optimizing compressed air energy storage(CAES)in low-grade salt mines,advancing their role in renewable energy integration.
基金financially supported by National Natural Science Foundation of China(No.U2241223)Pre-Research Foundation of China(No.909010203-202).
文摘Nano-twinned copper(nt-Cu),with a preferred orientation,is highly promising as interconnect materials in high-density advanced packaging due to its considerable mechanical strength,excellent electrical conductivity,and resistance to thermal migration.However,its application is impeded by sulfur-containing byproducts from the electroplating process,exacerbating the formation of Kirkendall voids within solder joints during thermal aging.Herein,through the incorporation of Zinc(Zn)into the nt-Cu layer,we develop a nt-Cu/Zn composite structure.Our findings provide the first definitive confirmation of the mechanism by which sulfur atoms migrate to the Cu_(3)Sn/nt-Cu interface through interstitial diffusion,thereby reducing the activation energy for vacancy formation.We further demonstrate that Zn effectively an-choring sulfur atoms,forming ZnS within the nt-Cu layer during heat treatment,which increases the vacancy formation energy and inhibits the development of Kirkendall voids.Remarkably,no Kirkendall voids are observed in the modified interconnects even after prolonged aging at 150℃ for 1000 h.The nt-Cu/Zn composite metallization layers significantly decrease the growth rate of interfacial intermetallic compounds by 33.6% and enhance the shear strength of solder interconnections to 228.9%.This research underscores the potential of nt-Cu in advanced electronic packaging,offering new pathways for improving the power density and reliability of electronic devices.
基金supported by the National Natural Science Foundation of China(Grant Nos.12022210 and 12032001)。
文摘Voids play an important role in the fatigue behaviour of polycrystal materials.In this paper,the effects of three factors affecting the stress concentration factors(SCFs)near voids,i.e.,size,depth,and applied load,are investigated by employing crystal plasticity constitutive models in polycrystal bulks.The results indicate that SCF is dominated by the void size,while void depth and stress level play secondary roles.The SCF fluctuates by the orientation differences among grains and increases with increasing the size of the void.Finally,based on sensitivity examination of orientations and configurations of grains sur-rounding the void,an empirical multivariable-coupled formula is proposed to assess SCF near voids considering anisotropy,and the presented model is in good agreement with the simulation results.
基金the National Natural Science Foundation of China(Grant Nos.42172298,42002289)the Shanghai Geological Star Program for their financial support.
文摘Compaction grouting is primarily applied based on empiricism,and it is challenging to quantify its densification effect.To address this issue,five sets of laboratory model tests on ideal compaction grouting were conducted,with varying pressures from 400 kPa to 800 kPa,to quantitatively evaluate the densification effect in unsaturated soils.The response of surrounding soil during compaction grouting was monitored.The changes in dry density and void ratio induced by compaction grouting were obtained by monitoring volumetric water content to determine compaction efficiency.In addition,a model was developed and validated to predict the effective compaction range.The results show that soil dry density increased rapidly during compaction grouting before being stabilized at a consistent level.As expected,it is positively correlated with grouting pressures(GPs)and negatively correlated with the distance from the injection point.At higher GPs,the difference in densification effect around the injection point after compaction grouting was significant.Interestingly,variations in ultimate dry density and peak earth pressures perpendicular to the injection direction exhibited axisymmetric behavior around the injection point when comparing the dry density and earth pressure results.Furthermore,soil densification resulted in a decrease in suction.However,no significant effect of GP on suction at different soil positions was observed.Moreover,compaction efficiency decreased with increasing distance from the injection point,showing a strong linear relationship.In addition,the model results for the effective compaction range were basically consistent with the extrapolated values from the experimental results.
基金supported by the National Natural Science Foundation of China(Grant Nos.12232005 and 12072101).
文摘Large-grain REBa_(2)Cu_(3)O_(7-δ)(REBCO,RE=rare earth)bulk superconductors offer promising magnetic field trapping capabilities due to their high critical current density,making them ideal for many important applications such as trapped field magnets.However,for such large-grain superconductor bulks,there are lots of voids and cracks forming during the process of melting preparation,and some of them can be up to hundreds of microns or even millimeters in size.Consequently,these larger size voids/cracks pose a great threat to the strength of the bulks due to the inherent brittleness of superconductor REBCO materials.In order to ensure the operational safety of related superconducting devices with bulk superconductors,it is firstly important to accurately detect these voids/cracks in them.In this paper,we proposed a method for quantitatively evaluating multiple voids/cracks in bulk superconductors through the magnetic field and displacement response signals at superconductor bulk surface.The proposed method utilizes a damage index constructed from the magnetic field signals and displacement responses to identify the number and preliminary location of multiple defects.By dividing the detection area into subdomains and combining the magnetic field signals with displacement responses within each subdomain,a particle swarm algorithm was employed to evaluate the location and size parameters of the defects.In contrast to other evaluation methods using only magnetic field or displacement response signals,the combined evaluation method using both signals can identify the number of cracks effectively.Numerical studies demonstrate that the morphology of voids and cracks reconstructed using the proposed algorithm ideally matches real defects and is applicable to cases where voids and cracks coexist.This study provides a theoretical basis for the quantitative detection of voids/cracks in bulk superconductors.
基金supported by the National Natural Science Foundation of China(Grant No.12372367)the Special Foundation of the Institute of Fluid Physics of China Academy of Engineering Physics(Grant No.2022-YCHT-0641).
文摘This work investigates the dynamic response of a monocrystalline nickel-titanium(NiTi)alloy at the atomic scale.The results deduced from non-equilibrium molecular dynamics modeling demonstrate that no shear deformation band(SDB)appears in the sample at an impact velocity of less than 0.75 km/s.As this velocity increases,shear deformations become pronouncedly localized,and the average spacing between SDBs decreases until it stabilizes.Combining shear stress and particle velocity profiles,the survival of SDBs is found to be closely associated with plastic deformation.The dislocations clustering around SDBs predominantly exhibit 100 partial dislocations,whereas 1/2111 full dislocations are dominant in those regions without SDBs.Void nucleation always occurs on SDBs.Subsequently,void growth promotes a change in the SDB distribution characteristic.For the case without SDB,voids are randomly nucleated,and the void growth exhibits a non-uniform manner.Thus,there is an interaction between shear localization and void evolution in the NiTi alloy subjected to intensive loading.This study is expected to provide in-depth insights into the microscopic mechanism of NiTi dynamic damage.
基金financially supported by the National Natural Science Foundation of China(Nos.62274172 and 62304143)High-level Talent Innovation and Entrepreneurship Plan of Shenzhen Key Technology Research and Development Team Funding Application(No.JSGGKQTD20221101115650008)+2 种基金Shenzhen-Hong Kong-Macao Science and Technology Plan Project(Category C)(No.SGDX20220530111004028)Macao Science and Technology Development Fund(FDCT)for funding(No.0013/2024/RIB1)the Multi-Year Research Grant(MYRG)from University of Macao(Nos.MYRG-GRG2023-00140-IAPME-UMDF and MYRG-GRG2024-00206-IAPME)
文摘Kirkendall voids(KVs)at the Cu/Sn interface are a typical failure in integrated circuits,leading to solder joint cracking and electrical disconnection.Although the formation of KVs has been attributed to the difference in atomic diffusion rates at the Cu/Sn interface,the role of Cu intrinsic"quality"parameters(crystal defects)in this process remains unclear.This work systematically investigated the effects of Cu crystal defects on KVs:Cu substrates with different lattice defects and grain boundaries were prepared using proprietary electrodeposition additives,and the number of defects was quantitatively characterized by micro-strain,geometric dislocation density,and geometric phase analysis.The thermal aging experiments further showed that the formation of intermetallic compounds and KVs was related to crystal defect energy.When the grain boundary energy was higher than the lattice energy,the additional driving force resulted in short-circuit diffusion,causing local Cu depletion and voids.The lowcrystal-defect samples maintained the local Cu/Sn interdiffusion equilibrium,resulting in fewer voids after 1000 h.This study emphasizes that regulating the crystal defects can reduce KVs and provides a new insight for improving the integrated solder joint's reliability.
基金the Shanxi Province Science Foundation(20210302123150)the National Key Research and Development Program(2021YFB2500300)+3 种基金the National Natural Science Foundation of China(223B1012,22409114)the Beijing Natural Science Foundation(L243019)the Anhui Science and Technology Innovation Tackling Key Problems Plan Project(202423h08050005)the China Postdoctoral Science Foundation(2023M731920)。
文摘With the ever-increasing energy density requirements for sulfide-based all-solid-state batteries,lithium metal is regarded as an ideal candidate for anode materials.However,the dynamic degradation of solidsolid contact between lithium anode and solid electrolyte remains a major challenge for the application of all-solid-state lithium metal batteries(ASSLMBs).The poor solid-solid contact problem is caused by the continuous accumulation of lithium voids,which results from the limited diffusion rate of lithium in the bulk phase.In this study,we design a three-dimensional(3D)lithiophilic graphitized carbon nanotubebased(LNT)interlayer to address interfacial issues.The interlayers effectively regulate lithium stripping and suppress the growth of lithium voids via improved lithium diffusion,leading to a conformal interface during continuous cycling.The lithium metal anode with the interlayer delivers an areal capacity of 12.96 mA h cm^(-2),and when paired with a LiNi_(0.9)Co_(0.05)Mn_(0.05)O_(2)(NCM9)cathode,the battery retains over 91%capacity retention after 100 cycles at room temperature.This work provides an effective strategy for interface stabilization in high-capacity and long-life ASSLMBs.
基金supported by the Ministry of Industry and Information Technology of China(grant number TC220A04W-7,203)CNNC Youth Elite Scientific Research Project,the National Key R&D Plan of China(grant number 2020YFB1901600)the National Science Technology Major Project of China(grant numbers 2017ZX06902012 and 2017ZX06901024).
文摘Nickel-based alloys are the primary structural materials in steam generators of high-temperature gas reactors.To understand the irradiation effect of nickel-based alloys,it is necessary to examine dislocation movement and its interaction with irradiation defects at the microscale.Hardening due to voids and Ni_(3)Al precipitates may significantly impact irradiation damage in nickel-based alloys.This paper employs the molecular dynamics method to analyze the interaction between edge dislocations and irradiation defects(void and Ni_(3)Al precipitates)in face-centered cubic nickel.The effects of temperature and defect size on the interaction are also explored.The results show that the interaction process of the edge dislocation and irradiation defects can be divided into four stages:dislocation free slip,dislocation attracted,dislocation pinned,and dislocation unpinned.Interaction modes include the formation of stair-rod dislocations and the climbing of extended dislocation bundles for voids,as well as the generation of stair-rod dislocation and dislocation shear for precipitates.Besides,the interactions of edge dislocations with voids and Ni_(3)Al precipitates are strongly influenced by temperature and defect size.
基金the funding support from the National Natural Science Foundation of China(Grant Nos.52350004 and 51925903).
文摘The freeze-thaw(FT)behavior of porous materials(PMs)involves the coupling of the thermo-hydromechanical(THM)processes and is significantly influenced by the microstructure.However,modeling FT in unsaturated PMs remains an open issue,and the influence of microstructure is not yet fully understood.To address these challenges,we propose a THM model for FT in PMs that considers microstructure and variable air content.In this work,a non-equilibrium thermodynamic approach is proposed to capture ice formation/melting,the microstructure is accounted for utilizing micromechanics,and the FT processes in air-entrained PMs are formulated within the proposed THM model.This model incorporates variable air void characteristics,e.g.air content,spacing factor,specific surface area,and supercooled water-filled regimes,and distinguishes the roles of air voids between freezing and thawing.The FT behaviors,including deformation,ice formation/melting,spacing factor,and pore water pressure evolutions,are focused.Comparisons with experimental results,confirm the capability of the present model.The results demonstrate the effects of variable air voids on the FT behavior of air-entrained PMs.The findings reveal that assuming fixed air void characteristics can lead to underestimation of pore pressure and deformation,particularly at low air content.Additionally,air voids act as cryo-pumps during freezing and when the cooling temperature stabilizes.During thawing,air voids supply gas to the melting sites(i.e.“gas escape”),preventing further significant deformation reduction.These results can provide novel insights for understanding the frost damage of PMs.
文摘Dear Editor,Primary bladder neck obstruction(PBNO)affects approximately 28%–54%of men[1].Its etiology remains unclear.Symptoms of PBNO present as voiding(e.g.,decreased force of stream,hesitancy,intermittent stream,and incomplete emptying),storage(e.g.,frequency,urgency,urge incontinence,and nocturia),or a combination of both[2].Untreated PBNO can lead to bladder dysfunction,bladder diverticula,hydronephrosis,and impaired renal function[3].
基金funded by the Key Project of Science&Technology Research ofChina Academy of Railway Sciences,grant number 2023YJ022.
文摘Detecting internal defects,particularly voids behind linings,is critical for ensuring the structural integrity of aging high-speed rail(HSR)tunnel networks.While ground-penetrating radar(GPR)is widely employed,systematic quantification of performance boundaries for air-coupled(A-CGPR)and ground-coupled(G-CGPR)systems within the complex electromagnetic environment of multilayer reinforced HSR tunnels remains limited.This study establishes physics-based quantitative performance limits for A-CGPR and G-CGPR through rigorously validated GPRMax finite-difference time-domain(FDTD)simulations and comprehensive field validation over a 300 m operational HSR tunnel section.Key performance metrics were quantified as functions of:(a)detection distance(A-CGPR:2.0–4.5 m;G-CGPR:≤0.1 m),(b)antenna frequency(A-CGPR:300 MHz;G-CGPR:400/900 MHz),(c)reinforcement configuration(unreinforced,single-layer,multilayer rebar),and(d)void geometry(axial length:0.1–1.0 m;radial depth:0.1–0.5 m).Key findings demonstrate:a.A-CGPR(300 MHz):Reliably detects axial voids≥0.3 m at distances≤3 m in minimally reinforced(single-layer rebar)linings(field R2=0.89).Performance degrades significantly at distances>3 m(>60%signal attenuation at 4.5 m)or under multilayer rebar interference,causing 25%–40%accuracy loss for voids<0.3 m.Optimal distance:2.0–2.5 m.b.G-CGPR(900 MHz):Achieves<5%size measurement error for axial voids≥0.1 m and radial voids≥0.2 m in unreinforced linings.Resolution degrades under multilayer reinforcement due to severe signal attenuation,increasing axial void detection error to 10%–20%for voids≥0.3 m and constraining radial size measurement.c.Synergistic Framework:A hybrid inspection protocol is proposed,integrating A-CGPR(20 km/h)for rapid large-area screening and targeted G-CGPR(3 km/h)for high-resolution verification of identified anomalies.This framework enhances NDT efficiency while reducing estimated lifecycle inspection costs by 34%compared to G-CGPR alone.This research provides the first physics-derived quantitative detection thresholds for A-CGPR and G-CGPR in multi-rebar HSR tunnels,validated through field-correlated simulations.Future work will focus on multi-frequency antenna arrays and deep learning algorithms to mitigate reinforcement interference.The established performance boundaries and hybrid framework offer critical guidance for optimizing tunnel lining inspection strategies in extensive HSR networks.
基金Project (2010DFA51650) supported by the Ministry of Science and Technology of China
文摘Multilayered Ti-Al based intermetallic sheets were fabricated by sintering alternately layered titanium and aluminum foils.The microstructure and phase formation of the obtained sheets under different sintering conditions were evaluated by various techniques.The results reveal that when the sintering temperature is above the melting point of aluminum,the self-propagating high-temperature synthesis reaction occurs between Ti and Al,and forms various phases of Ti-based solid solutions including α-Ti Ti3Al,TiAl,TiAl2 and α-Ti including TiAl3,etc.When the sintering time increased,Ti-based solid solution,TiAl2 and TiAl3 disappeared gradually,and the sheet containing Ti3Al and TiAl phases in a multilayered structure formed finally.A lot of voids were also observed in the sintered structures,which were caused by the melting Al,Kirkendall effect and the difference of molar volumes between reactants and products.The voids were eliminated and a dense sample was obtained by the following hot press.
基金Project(51275416)supported by the National Natural Science Foundation of China
文摘The bonding interface characteristic and shear strength of diffusion bonded Ti-17 titanium alloy at different bonding time were investigated. The results show that the average size of voids decreases while the amount of voids decreases after increasing to the maximum value with the increasing bonding time. The irregular void with a scraggly edge tends to an ellipse void with smooth surface and then changes to a tiny void with round shape. The grains across bonding interface occur at bonding time of 60 min. The shear strength of bond increases with increasing bonding time, and the highest shear strength of bond is 887.4 MPa at 60 min. The contribution of plastic deformation on the void closure and the increase of shear strength is significant even though the action time of plastic deformation is short.
