The seismic data of the Laoshan Uplift in the South Yellow Sea Basin reveal a low signal-tonoise ratio and low refl ection signal energy in the deep Mesozoic–Paleozoic strata.The main reason is that the Mesozoic-Pale...The seismic data of the Laoshan Uplift in the South Yellow Sea Basin reveal a low signal-tonoise ratio and low refl ection signal energy in the deep Mesozoic–Paleozoic strata.The main reason is that the Mesozoic-Paleozoic marine carbonate rock strata are directly covered by the Cenozoic terrestrial clastic rock strata,which form a strong shielding layer.To obtain the reflection signals of the strata below the strong shielding layer,a one-way wave equation bidirectional illumination analysis of the main observation system parameters was conducted by analyzing the mechanism of the strong shielding layer.Low-frequency seismic sources are assumed to have a high illumination intensity on the reflection layer below the strong shielding layer.Accordingly,optimized acquisition parameter suggestions were proposed,and reacquisition was performed at the existing survey line locations in the Laoshan Uplift area.The imaging of the newly acquired data in the middle and deep layers was drastically improved.It revealed the unconformity between the Sinian and Cambrian under the strong shielding layer.The study yielded new insights into the tectonic and sedimentary evolution of the Lower Paleozoic in the South Yellow Sea.展开更多
Purpose–To investigate the influence of vehicle operation speed,curve geometry parameters and rail profile parameters on wheel–rail creepage in high-speed railway curves and propose a multi-parameter coordinated opt...Purpose–To investigate the influence of vehicle operation speed,curve geometry parameters and rail profile parameters on wheel–rail creepage in high-speed railway curves and propose a multi-parameter coordinated optimization strategy to reduce wheel–rail contact fatigue damage.Design/methodology/approach–Taking a small-radius curve of a high-speed railway as the research object,field measurements were conducted to obtain track parameters and wheel–rail profiles.A coupled vehicle-track dynamics model was established.Multiple numerical experiments were designed using the Latin Hypercube Sampling method to extract wheel-rail creepage indicators and construct a parameter-creepage response surface model.Findings–Key service parameters affecting wheel–rail creepage were identified,including the matching relationship between curve geometry and vehicle speed and rail profile parameters.The influence patterns of various parameters on wheel–rail creepage were revealed through response surface analysis,leading to the establishment of parameter optimization criteria.Originality/value–This study presents the systematic investigation of wheel–rail creepage characteristics under multi-parameter coupling in high-speed railway curves.A response surface-based parameter-creepage relationship model was established,and a multi-parameter coordinated optimization strategy was proposed.The research findings provide theoretical guidance for controlling wheel–rail contact fatigue damage and optimizing wheel–rail profiles in high-speed railway curves.展开更多
In this study,an improved integrated radial basis function with nonuniform shape parameter is introduced.The proposed shape parameter varies in each support domain and is defined byθ=1/d_(max),where d_(max)is the max...In this study,an improved integrated radial basis function with nonuniform shape parameter is introduced.The proposed shape parameter varies in each support domain and is defined byθ=1/d_(max),where d_(max)is the maximum distance of any pair of nodes in the support domain.The proposed method is verified and shows good performance.The results are stable and accurate with any number of nodes and an arbitrary nodal distribution.Notably,the support domain should be large enough to obtain accurate results.This method is then applied for transient analysis of curved shell structures made from functionally graded materials with complex geometries.Through several numerical examples,the accuracy of the proposed approach is demonstrated and discussed.Additionally,the influence of various factors on the dynamic behavior of the structures,including the power-law index,different materials,loading conditions,and geometrical parameters of the structures,was investigated.展开更多
A novel porous shock absorption layer is put forward in this study, and the shock absorption performance of the porous shock absorption layer is evaluated based on three-dimensional pseudo-static analysis. The modifie...A novel porous shock absorption layer is put forward in this study, and the shock absorption performance of the porous shock absorption layer is evaluated based on three-dimensional pseudo-static analysis. The modified reaction acceleration method is adopted and validated in the three-dimensional model. Seven ground motions are selected and the peak ground acceleration is adjusted to 0.2 g, 0.4 g and 0.6 g. The impact of the void ratio and thickness of the porous shock absorption layer is studied, while the surrounding rock grade and tunnel depth are also investigated. The numerical results show that the porous shock absorption layer has good shock absorption performance and can effectively reduce the maximum internal force of the secondary lining, but it cannot reduce the maximum horizontal relative displacement of the secondary lining. The circumferential rubber strip in the porous shock absorption layer will reduce shock absorption performance. The results of parameter analysis indicate that the shock absorption performance of the porous shock absorption layer increases with the increase of the void ratio and thickness, and it has good shock absorption performance under different surrounding rock grades and tunnel depths.展开更多
BACKGROUND Sagittal spinopelvic alignment(SSA)is essential for preserving a stable and effective upright posture and locomotion.Although alterations in the SSA are recognised to induce compensatory modifications in th...BACKGROUND Sagittal spinopelvic alignment(SSA)is essential for preserving a stable and effective upright posture and locomotion.Although alterations in the SSA are recognised to induce compensatory modifications in the pelvis,hips,and knees,the inverse relationship concerning knee pathology undergoing total knee arthroplasty(TKA)has been examined by a limited number of studies,yielding inconclusive results.AIM To generate evidence of the effect of TKA on the SSA from existing literature.METHODS Databases like PubMed,EMBASE,and Scopus were used to identify articles related to the“knee spine syndrome”phenomenon using a combination of subject terms and keywords such as“spinopelvic parameters”,“sagittal spinal balance”,and“total knee arthroplasty”were used with appropriate Boolean operators.Studies measuring the SSA following TKA were included,and research was conducted as per preferred reporting items for systematic review and metaanalysis guidelines.RESULTS A total of 475 participants had undergone TKA,and six studies measuring SSA were analysed.Following TKA,pelvic tilt was the only parameter that showed significant changes,while lumbar lordosis(LL),pelvic incidence,and sacral slope were non-significant,as evident from the forest plots.CONCLUSION The body's sagittal alignment is a complex balance between pelvic,spine,and lower extremity parameters.TKA,while having the potential to correct the flexion contracture,can also correct it.Still,the primary SSA for spinal pathology,i.e.,LL,may not be corrected in patients with co-existent spinal degenerative disease.展开更多
Investigating the correlation between micronucleus formation and male infertility has the potential to improve clinical diagnosis and deepen our understanding of pathological progression. Our study enrolled 2252 male ...Investigating the correlation between micronucleus formation and male infertility has the potential to improve clinical diagnosis and deepen our understanding of pathological progression. Our study enrolled 2252 male patients whose semen was analyzed from March 2023 to July 2023. Their clinical data, including semen parameters and age, were also collected. Genetic analysis was used to determine whether the sex chromosome involved in male infertility was abnormal (including the increase, deletion, and translocation of the X and Y chromosomes), and subsequent semen analysis was conducted for clinical grouping purposes. The participants were categorized into five groups: normozoospermia, asthenozoospermia, oligozoospermia, oligoasthenozoospermia, and azoospermia. Patients were randomly selected for further study;41 patients with normozoospermia were included in the control group and 117 patients with non-normozoospermia were included in the study group according to the proportions of all enrolled patients. Cytokinesis-block micronucleus (CBMN) screening was conducted through peripheral blood. Statistical analysis was used to determine the differences in micronuclei (MNi) among the groups and the relationships between MNi and clinical data. There was a significant increase in MNi in infertile men, including those with azoospermia, compared with normozoospermic patients, but there was no significant difference between the genetic and nongenetic groups in azoospermic men. The presence of MNi was associated with sperm concentration, progressive sperm motility, immotile spermatozoa, malformed spermatozoa, total sperm count, and total sperm motility. This study underscores the potential utility of MNi as a diagnostic tool and highlights the need for further research to elucidate the underlying mechanisms of male infertility.展开更多
The accurate selection of operational parameters is critical for ensuring the safety,efficiency,and automation of Tunnel Boring Machine(TBM)operations.This study proposes a similarity-based framework integrating model...The accurate selection of operational parameters is critical for ensuring the safety,efficiency,and automation of Tunnel Boring Machine(TBM)operations.This study proposes a similarity-based framework integrating model-based boring indexes(derived from rock fragmentation mechanisms)and Euclidean distance analysis to achieve real-time recommendations of TBM operational parameters.Key performance indicators-thrust(F),torque(T),and penetration(p)-were used to calculate three model-based boring indexes(a,b,k),which quantify dynamic rock fragmentation behavior.A dataset of 359 candidate samples,reflecting diverse geological conditions from the Yin-Chao water conveyance project in Inner Mongolia,China,was utilized to validate the framework.The system dynamically recommends parameters by matching real-time data with historical cases through standardized Euclidean distance,achieving high accuracy.Specifically,the mean absolute error(MAE)for rotation speed(n)was 0.10 r/min,corresponding to a mean absolute percentage error(MAPE)of 1.09%.For advance rate(v),the MAE was 3.4 mm/min,with a MAPE of 4.50%.The predicted thrust(F)and torque(T)values exhibited strong agreement with field measurements,with MAEs of 270 kN and 178 kN∙m,respectively.Field applications demonstrated a 30%reduction in parameter adjustment time compared to empirical methods.This work provides a robust solution for real-time TBM control,advancing intelligent tunneling in complex geological environments.展开更多
AIM:To analyze the characteristics and correlation of phacoemulsification parameters and anterior segment parameters in cataract patients with different blood glucose levels.METHODS:A total of 45 type 2 diabetic catar...AIM:To analyze the characteristics and correlation of phacoemulsification parameters and anterior segment parameters in cataract patients with different blood glucose levels.METHODS:A total of 45 type 2 diabetic cataract patients(45 eyes)treated in our hospital from March 2023 to April 2024 were stratified into two groups based on glycosylated hemoglobin(HbA1c)levels:group A:HbA1c<7%(n=18)and group B:7%≤HbA1c<8.5%(n=27);a total of 94 age-matched age-related cataract patients(94 eyes)were enrolled as the control group(group C).All underwent phacoemulsification with intraocular lens implantation.Anterior segment parameters,including corneal,lens and anterior chamber measurements,were recorded.Correlations between phacoemulsification parameters and anterior segment parameters were analyzed,and differences among groups were compared.RESULTS:In groups A and B,effective phacoemulsification time(EPT)negatively correlated with corneal endothelial cell density(CECD)(r=-0.315,P=0.035).Average phacoemulsification time(APT)positively correlated with the anterior corneal surface radius of curvature(Rm;r=0.402,P=0.006)and negatively correlated with the flat axis meridian curvature(K 1),steep axis meridian curvature(K 2),mean curvature(Km)of the anterior corneal surface,and lens density at 6 mm zones(PDZ3;all P<0.05).Average phacoemulsification energy(AVE)positively correlated with mean lens density(LD-mean),lens density at 2 mm zones(PDZ1),lens density at 4 mm zones(PDZ2),and PDZ3(all P<0.05),and negatively with pupil diameter(r=-0.385,P=0.009).In the group C,EPT showed a positive correlation with Pentacam nucleus staging(PNS)density grade,PDZ1,PDZ2,and PDZ3(all P<0.05).A positive correlation was observed between AVE and PNS classification(r=0.246,P=0.018).Conversely,AVE exhibited a negative correlation with CECD(r=-0.245,P=0.018).EPT in groups A and B was higher than that in the group C(P<0.05).Both EPT and APT in the group B were higher than those in the group A(P<0.05).In diabetic cataract patients,CECD,corneal density(CD),and posterior corneal surface height positively correlated with diabetes duration(P<0.05).Posterior corneal surface K 1 and Rm positively correlated with 7%≤HbA1c<8.5%(P<0.05).Total corneal astigmatism negatively correlated with HbA1c,2-hour post-breakfast blood glucose(2hPBG),and fasting insulin(FINS;P<0.05).CD and lens thickness(LT)positively correlated with FINS(P<0.05).CONCLUSION:Phacoemulsification parameters and blood glucose-related indices exhibited varying degrees of correlation with anterior segment parameters in cataract patients with different blood glucose levels.EPT in diabetic cataract patients was higher than that in age-related cataract patients,while EPT and APT in diabetic cataract patients with poor glycemic control were higher than those with good glycemic control.展开更多
The impact of different global and local variables in urban development processes requires a systematic study to fully comprehend the underlying complexities in them.The interplay between such variables is crucial for...The impact of different global and local variables in urban development processes requires a systematic study to fully comprehend the underlying complexities in them.The interplay between such variables is crucial for modelling urban growth to closely reflects reality.Despite extensive research,ambiguity remains about how variations in these input variables influence urban densification.In this study,we conduct a global sensitivity analysis(SA)using a multinomial logistic regression(MNL)model to assess the model’s explanatory and predictive power.We examine the influence of global variables,including spatial resolution,neighborhood size,and density classes,under different input combinations at a provincial scale to understand their impact on densification.Additionally,we perform a stepwise regression to identify the significant explanatory variables that are important for understanding densification in the Brussels Metropolitan Area(BMA).Our results indicate that a finer spatial resolution of 50 m and 100 m,smaller neighborhood size of 5×5 and 3×3,and specific density classes—namely 3(non-built-up,low and high built-up)and 4(non-built-up,low,medium and high built-up)—optimally explain and predict urban densification.In line with the same,the stepwise regression reveals that models with a coarser resolution of 300 m lack significant variables,reflecting a lower explanatory power for densification.This approach aids in identifying optimal and significant global variables with higher explanatory power for understanding and predicting urban densification.Furthermore,these findings are reproducible in a global urban context,offering valuable insights for planners,modelers and geographers in managing future urban growth and minimizing modelling.展开更多
Damage to electrical equipment in an earthquake can lead to power outage of power systems.Seismic fragility analysis is a common method to assess the seismic reliability of electrical equipment.To further guarantee th...Damage to electrical equipment in an earthquake can lead to power outage of power systems.Seismic fragility analysis is a common method to assess the seismic reliability of electrical equipment.To further guarantee the efficiency of analysis,multi-source uncertainties including the structure itself and seismic excitation need to be considered.A method for seismic fragility analysis that reflects structural and seismic parameter uncertainty was developed in this study.The proposed method used a random sampling method based on Latin hypercube sampling(LHS)to account for the structure parameter uncertainty and the group structure characteristics of electrical equipment.Then,logistic Lasso regression(LLR)was used to find the seismic fragility surface based on double ground motion intensity measures(IM).The seismic fragility based on the finite element model of an±1000 kV main transformer(UHVMT)was analyzed using the proposed method.The results show that the seismic fragility function obtained by this method can be used to construct the relationship between the uncertainty parameters and the failure probability.The seismic fragility surface did not only provide the probabilities of seismic damage states under different IMs,but also had better stability than the fragility curve.Furthermore,the sensitivity analysis of the structural parameters revealed that the elastic module of the bushing and the height of the high-voltage bushing may have a greater influence.展开更多
This research investigates the influence of indoor and outdoor factors on photovoltaic(PV)power generation at Utrecht University to accurately predict PV system performance by identifying critical impact factors and i...This research investigates the influence of indoor and outdoor factors on photovoltaic(PV)power generation at Utrecht University to accurately predict PV system performance by identifying critical impact factors and improving renewable energy efficiency.To predict plant efficiency,nineteen variables are analyzed,consisting of nine indoor photovoltaic panel characteristics(Open Circuit Voltage(Voc),Short Circuit Current(Isc),Maximum Power(Pmpp),Maximum Voltage(Umpp),Maximum Current(Impp),Filling Factor(FF),Parallel Resistance(Rp),Series Resistance(Rs),Module Temperature)and ten environmental factors(Air Temperature,Air Humidity,Dew Point,Air Pressure,Irradiation,Irradiation Propagation,Wind Speed,Wind Speed Propagation,Wind Direction,Wind Direction Propagation).This study provides a new perspective not previously addressed in the literature.In this study,different machine learning methods such as Multilayer Perceptron(MLP),Multivariate Adaptive Regression Spline(MARS),Multiple Linear Regression(MLR),and Random Forest(RF)models are used to predict power values using data from installed PVpanels.Panel values obtained under real field conditions were used to train the models,and the results were compared.The Multilayer Perceptron(MLP)model was achieved with the highest classification accuracy of 0.990%.The machine learning models used for solar energy forecasting show high performance and produce results close to actual values.Models like Multi-Layer Perceptron(MLP)and Random Forest(RF)can be used in diverse locations based on load demand.展开更多
Serving as the initiating explosive devices between the propellant tank and the engines,metal-based rupture diaphragms are widely used in ramjet igniters owing to the advantages provided by their simple structure,smal...Serving as the initiating explosive devices between the propellant tank and the engines,metal-based rupture diaphragms are widely used in ramjet igniters owing to the advantages provided by their simple structure,small size,and low cost.However,the reliability of rupture pressure directly affects the success of engine ignition and rocket launch,which is mainly influenced by factors like material,structure,and residual thickness of the surface notch of the diaphragm.Among those,the geometry of the notch is easy to define and control when compared to the mechanical parameters of the ruptured diaphragm.Thus,to make the diaphragm rupture(1A30 Al)within the required pressure range(0.4 MPa±3.5%)with highly sensitive and reliability,we draw inspiration from the arthropod’s force-sensitive slit organ which encompasses curved microgrooves to design a Ω-shaped notch for the rupture diaphragm.Finite element analysis is used to study the relationship between the burst pressure and geometric dimension of theΩ-shaped and bioinspired microgroove.Based on that,metal-based rupture diaphragms are fabricated by femtosecond laser processing technology,followed by rupture tests.Experiment results demonstrate that the practical rupture pressure of the diaphragm is highly consistent with the finite element analysis results,which verifies the effectiveness of the bionic design.展开更多
Hydrogen(H_(2))is a promising renewable energy which finds wide applications as the world gears toward low-carbon economy.However,current H_(2) production via steam methane reforming of natural gas or gasification of ...Hydrogen(H_(2))is a promising renewable energy which finds wide applications as the world gears toward low-carbon economy.However,current H_(2) production via steam methane reforming of natural gas or gasification of coal are laden with high CO_(2) footprints.Recently,methane(CH_(4))pyrolysis has emerged as a potential technology to generate low-carbon H_(2) and solid carbon.In this review,the current state-of-art and recent progress of H_(2) production from CH_(4) pyrolysis are reviewed in detail.Aspects such as funda-mental mechanism and chemistry involved,effect of process parameters on the conversion efficiency and reaction kinetics for various reaction media and catalysts are elucidated and critically discussed.Temper-ature,among other factors,plays the most critical influence on the methane pyrolysis reaction.Molten metal/salt could lower the operating temperature of methane pyrolysis to<1000℃,whereas plasma technology usually operates in the regime of>1000℃.Based on the reaction kinetics,metal-based cata-lysts were more efficient in lowering the activation energy of the reaction to 29.5-88 kJ/mol from that of uncatalyzed reaction(147-420.7 kJ/mol).Besides,the current techno-economic performance of the pro-cess reveals that the levelized cost of H_(2) is directly influenced by the sales price of carbon(by-product)generated,which could offset the overall cost.Lastly,the main challenges of reactor design for efficient product separation and retrieval,as well as catalyst deactivation/poisoning need to be debottlenecked.展开更多
Dynamic analysis of the tethered satellite system(TSS)can provide a fundamental guideline to the evaluation of performance and robust design of the system examined.Uncertainties inherited with the parameters would ind...Dynamic analysis of the tethered satellite system(TSS)can provide a fundamental guideline to the evaluation of performance and robust design of the system examined.Uncertainties inherited with the parameters would induce unexpected variation of the response and deteriorate the reliability of the system.In this work,the effect of uncertain mass of the satellites on the deployment and retrieval dynamics of the TSS is investigated.First the interval mode is employed to take the variation of mass of satellite into account in the processes of deployment and retrieval.Then,the Chebyshev interval method is used to obtain the lower and upper response bounds of the TSS.To achieve a smooth and reliable implementation of deployment and retrieval,the nonlinear programming based on the Gauss pseudospectral method is adopted to obtain optimal trajectory of tether velocity.Numerical results show that the uncertainties of mass of the satellites have a distinct influence on the response of tether tension in the processes of deployment and retrieval.展开更多
In order to improve the performance and service life of the Leningrader seal of the Stirling engine piston rod,interference,pre-load and friction coefficient were taken as influencing factors,and the curved surface re...In order to improve the performance and service life of the Leningrader seal of the Stirling engine piston rod,interference,pre-load and friction coefficient were taken as influencing factors,and the curved surface response method was adopted to reduce the contact stress of sealing surface and von Mises stress of the sealing sleeve as the response index,with the optimization goal of reducing wear and extending life.The above three key parameters are analyzed and optimized,the influence of each parameter on the sealing performance and service life is obtained,and the best combination scheme of the three is determined.The results show that the interaction between pre-tightening force and interference fit has the greatest impact on contact stress.The interaction between interference fit and friction coeffi-cient has the most significant effect on von Mises stress.The optimized parameters can reduce the maximum contact stress and maximum von Mises stress of the sealing sleeve by 26.3%and 20.6%,respectively,under a media pressure of 5-9 MPa.Test bench verification shows that the leakage of the optimized sealing device in 12 h is reduced by 0.44 cc·min^(-1)(1 cc=1 cm^(3)).The wear rate of the sealing sleeve is 1.08%before optimization and 0.45%after optimization,indicating that the optimized parameters in this paper are effective.展开更多
Foot-and-mouth disease(FMD)is a viral disease that affects cloven-hoofed animals including cattle,pigs,and sheep,hence causing export bans among others,causing high economic losses due to reduced productivity.The glob...Foot-and-mouth disease(FMD)is a viral disease that affects cloven-hoofed animals including cattle,pigs,and sheep,hence causing export bans among others,causing high economic losses due to reduced productivity.The global effect of FMD is most felt where livestock rearing forms an important source of income.It is therefore important to understand the modes of transmission of FMD to control its spread and prevent its occurrence.This work intends to address these dynamics by including the efficacy of active migrant animals transporting the disease from one area to another in a fuzzy mathematical modeling framework.Historical models of epidemics are determinable with a set of deterministic parameters and this does not reflect on real-life scenarios as observed in FMD.Fuzzy theory is used in this model as it permits the inclusion of uncertainties in the model;this makes the model more of a reality regarding disease transmission.A time lag,in this case,denotes the incubation period and other time-related factors affecting the spread of FMD and,therefore,is added to the current model for FMD.To that purpose,the analysis of steady states and the basic reproduction number are performed and,in addition,the stability checks are conveyed in the fuzzy environment.For the numerical solution of the model,we derive the Forward Euler Method and the fuzzy delayed non-standard finite difference(FDNSFD)method.Analytical studies of the FDNSFD scheme are performed for convergence,non-negativity,boundedness,and consistency analysis of the numerical projection to guarantee that the numerical model is an accurate discretization of the continuous dynamics of FMD transmission over time.In the following simulation study,we show that the FDNSFD method preserves the characteristics of the constant model and still works if relatively large time steps are employed;this is a bonus over the normal finite difference technique.The study shows how valuable it is to adopt fuzzy theory and time delays when simulating the transmission of the epidemic,especially for such diseases as FMD where uncertainty and migration have a defining role in transmission.This approach gives more sound and flexible grounds for analyzing and controlling the outbreak of FMD in various situations.展开更多
Objectives:The movement towards personalization of cochlear implantation has continued to generate interest about variabilities in cochlear size.In a recent metaanalysis,Atalay et al.(2022)examined organ of corti leng...Objectives:The movement towards personalization of cochlear implantation has continued to generate interest about variabilities in cochlear size.In a recent metaanalysis,Atalay et al.(2022)examined organ of corti length,cochlear lateral wall,and“A”value and found that most covariates,other than congenital sensorineural hearing loss,did not impact cochlear size via these measurements.However,no meta-analysis exists on how patient-specific variables could impact other cochlear size measurements,such as cochlear height(CH),and“B”value(defined as the distance between opposite lateral walls and perpendicular to“A”value).The purpose of this systematic review and meta-analysis is to examine how patient-specific variables impact additional cochlear size measurements to assist clinical decisionmaking.Databases reviewed:A systematic review for cochlear size measurements using PRISMA methodology was performed using PubMed,CINAHL,and MEDLINE from database inception to October 1st,2022.Methods:Search terms used included English,cochlea,size,histology,anatomy,and human.Inclusion criteria were measurements for human cochlea,full-text articles,and articles in English.Primary measurements were“B”value and CH,as these measurements differ from the recent meta-analysis on this topic.Cochlear duct length(CDL)was also included.A random-effects continuous model for meta-analysis was performed.Measurements were stratified by gender(male/female)and disease type(sensorineural hearing loss(SNHL)/conductive hearing loss(CHL)).Results:A total of 7 articles met final inclusion criteria from a total of 674 articles received on initial search,resulting in 2263 total human cochleae.There was a statistical difference between male CDL(n=681 cochlea)compared to female CDL(n=657)from four articles(p<0.001;Cohen’s d effect size(ES):0.421;95%confidence intervals(CI):0.171,0.671).The frequency weighted mean for male CDL was 33.5 mm±1.8 mm and the frequency weighted mean for female CDL was 32.4 mm±1.5 mm with an unstandardized mean difference of 0.854 mm.There was no statistical difference between male“B”value(n=329)and female“B”value(n=349)for cochlea from two studies(p=0.184;Cohen’s d ES:0.410;95%CI:0.194,1.014).The frequency weighted mean for male“B”value was 6.5 mm±0.1 mm and the frequency weighted mean for female“B”value was 6.4 mm±0.1 mm with an unstandardized mean difference of 0.126 mm.There was no statistical difference between CH for SNHL(n=282)and CHL(n=275)from two studies(p=0.486;ES:0.085;95%CI:0.323,0.153,F ig.3).The frequency weighted mean for SNHL CH was 4.6 mm±0.8 mm and the frequency weighted mean for CHL CH was 4.3 mm±0.8 mm with an unstandardized mean difference of 0.032 mm.Conclusion:Male CDL is statistically larger than female CDL.There is no statistically significant association between gender or hearing loss type and“B”value or CH.The effect size for all comparisons is small,indicating little practical significance between any existing differences.The results of this study provide two additional cochlear metrics and indicate similar findings to the study by Atalay and colleagues as patient-specific characteristics appear to have no statistically significantly impact on cochlear size.展开更多
AIM:To develop a deep learning-based model for automatic retinal vascular segmentation,analyzing and comparing parameters under diverse glucose metabolic status(normal,prediabetes,diabetes)and to assess the potential ...AIM:To develop a deep learning-based model for automatic retinal vascular segmentation,analyzing and comparing parameters under diverse glucose metabolic status(normal,prediabetes,diabetes)and to assess the potential of artificial intelligence(AI)in image segmentation and retinal vascular parameters for predicting prediabetes and diabetes.METHODS:Retinal fundus photos from 200 normal individuals,200 prediabetic patients,and 200 diabetic patients(600 eyes in total)were used.The U-Net network served as the foundational architecture for retinal arteryvein segmentation.An automatic segmentation and evaluation system for retinal vascular parameters was trained,encompassing 26 parameters.RESULTS:Significant differences were found in retinal vascular parameters across normal,prediabetes,and diabetes groups,including artery diameter(P=0.008),fractal dimension(P=0.000),vein curvature(P=0.003),C-zone artery branching vessel count(P=0.049),C-zone vein branching vessel count(P=0.041),artery branching angle(P=0.005),vein branching angle(P=0.001),artery angle asymmetry degree(P=0.003),vessel length density(P=0.000),and vessel area density(P=0.000),totaling 10 parameters.CONCLUSION:The deep learning-based model facilitates retinal vascular parameter identification and quantification,revealing significant differences.These parameters exhibit potential as biomarkers for prediabetes and diabetes.展开更多
Large-scale Language Models(LLMs)have achieved significant breakthroughs in Natural Language Processing(NLP),driven by the pre-training and fine-tuning paradigm.While this approach allows models to specialize in speci...Large-scale Language Models(LLMs)have achieved significant breakthroughs in Natural Language Processing(NLP),driven by the pre-training and fine-tuning paradigm.While this approach allows models to specialize in specific tasks with reduced training costs,the substantial memory requirements during fine-tuning present a barrier to broader deployment.Parameter-Efficient Fine-Tuning(PEFT)techniques,such as Low-Rank Adaptation(LoRA),and parameter quantization methods have emerged as solutions to address these challenges by optimizing memory usage and computational efficiency.Among these,QLoRA,which combines PEFT and quantization,has demonstrated notable success in reducing memory footprints during fine-tuning,prompting the development of various QLoRA variants.Despite these advancements,the quantitative impact of key variables on the fine-tuning performance of quantized LLMs remains underexplored.This study presents a comprehensive analysis of these key variables,focusing on their influence across different layer types and depths within LLM architectures.Our investigation uncovers several critical findings:(1)Larger layers,such as MLP layers,can maintain performance despite reductions in adapter rank,while smaller layers,like self-attention layers,aremore sensitive to such changes;(2)The effectiveness of balancing factors depends more on specific values rather than layer type or depth;(3)In quantization-aware fine-tuning,larger layers can effectively utilize smaller adapters,whereas smaller layers struggle to do so.These insights suggest that layer type is a more significant determinant of fine-tuning success than layer depth when optimizing quantized LLMs.Moreover,for the same discount of trainable parameters,reducing the trainable parameters in a larger layer is more effective in preserving fine-tuning accuracy than in a smaller one.This study provides valuable guidance for more efficient fine-tuning strategies and opens avenues for further research into optimizing LLM fine-tuning in resource-constrained environments.展开更多
The rotor is the most important component of rotating machinery,and the vibration produced by its mass unbalance has a serious influence on the secure and steady operation of the machine,so an effective online suppres...The rotor is the most important component of rotating machinery,and the vibration produced by its mass unbalance has a serious influence on the secure and steady operation of the machine,so an effective online suppression technology is urgently needed.A new hydraulic unbalanced bionic self-recovery system is introduced,imitating the way of manually repairing faulty equipment.To accomplish the effect of actuator mass redistribution,the technology employs pressurized air to drive the quantitative transfer of liquid in the reservoir cavity at opposite positions.It can complete the online adjustment of the equipment's balancing state and suppress the unbalanced vibration of equipment in real time,which gives the equipment the ability to maintain an autonomous health state and improve equipment performance.The composition and working principle of the system are introduced in detail,and the key performance parameters,such as the minimum running speed and the balancing liquid transfer speed,are analyzed theoretically.The fluid-solid coupling model of the actuator was established,and the two-phase flow from inside the hydraulic unbalanced bionic self-recovery actuator was simulated under multiple working conditions and the performance parameters were quantitatively analyzed.A balancing simulation test bed was built,and its effectiveness was verified by performance parameter tests and unbalanced bionic self-recovery experiments.The experimental results show that the mass distribution adjustment of the balancing disk can be achieved using different viscosity balancing liquid,and the response of liquid viscosity 10 cSt is faster than that of liquid viscosity 100 cSt in the process of balancing liquid transfer,and the time is reduced by more than 75%;the system can reduce the simulated rotor amplitude from 18.3μm to 10.6μm online in real time,which provides technical support for the subsequent development of a new generation of bionic intelligent equipment.展开更多
基金“High precision prestack reverse time depth migration imaging of long array seismic data in the East China Sea Shelf Basin”of the National Natural Science Foundation of China(No.42106207)“Seismic acquisition technology for deep strata under strong shielding layers in the sea and rugged seabed”of Laoshan Laboratory Science and Technology Innovation Project(No.LSKJ202203404)“Research on the compensation methods of the middledeep weak seismic reflections in the South Yellow Sea based on multi-resolution HHT time-frequency analysis”of the National Natural Science Foundation of China(No.42106208).
文摘The seismic data of the Laoshan Uplift in the South Yellow Sea Basin reveal a low signal-tonoise ratio and low refl ection signal energy in the deep Mesozoic–Paleozoic strata.The main reason is that the Mesozoic-Paleozoic marine carbonate rock strata are directly covered by the Cenozoic terrestrial clastic rock strata,which form a strong shielding layer.To obtain the reflection signals of the strata below the strong shielding layer,a one-way wave equation bidirectional illumination analysis of the main observation system parameters was conducted by analyzing the mechanism of the strong shielding layer.Low-frequency seismic sources are assumed to have a high illumination intensity on the reflection layer below the strong shielding layer.Accordingly,optimized acquisition parameter suggestions were proposed,and reacquisition was performed at the existing survey line locations in the Laoshan Uplift area.The imaging of the newly acquired data in the middle and deep layers was drastically improved.It revealed the unconformity between the Sinian and Cambrian under the strong shielding layer.The study yielded new insights into the tectonic and sedimentary evolution of the Lower Paleozoic in the South Yellow Sea.
基金sponsored by the National Natural Science Foundation of China(Grant No.52405443)the Technology Research and Development Plan of China Railway(Grant No.N2023G063)the Fund of China Academy of Railway Sciences Corporation Limited(Grant No.2023YJ054).
文摘Purpose–To investigate the influence of vehicle operation speed,curve geometry parameters and rail profile parameters on wheel–rail creepage in high-speed railway curves and propose a multi-parameter coordinated optimization strategy to reduce wheel–rail contact fatigue damage.Design/methodology/approach–Taking a small-radius curve of a high-speed railway as the research object,field measurements were conducted to obtain track parameters and wheel–rail profiles.A coupled vehicle-track dynamics model was established.Multiple numerical experiments were designed using the Latin Hypercube Sampling method to extract wheel-rail creepage indicators and construct a parameter-creepage response surface model.Findings–Key service parameters affecting wheel–rail creepage were identified,including the matching relationship between curve geometry and vehicle speed and rail profile parameters.The influence patterns of various parameters on wheel–rail creepage were revealed through response surface analysis,leading to the establishment of parameter optimization criteria.Originality/value–This study presents the systematic investigation of wheel–rail creepage characteristics under multi-parameter coupling in high-speed railway curves.A response surface-based parameter-creepage relationship model was established,and a multi-parameter coordinated optimization strategy was proposed.The research findings provide theoretical guidance for controlling wheel–rail contact fatigue damage and optimizing wheel–rail profiles in high-speed railway curves.
基金Ho Chi Minh City University of Technology (HCMUT), VNU-HCM for supporting this study
文摘In this study,an improved integrated radial basis function with nonuniform shape parameter is introduced.The proposed shape parameter varies in each support domain and is defined byθ=1/d_(max),where d_(max)is the maximum distance of any pair of nodes in the support domain.The proposed method is verified and shows good performance.The results are stable and accurate with any number of nodes and an arbitrary nodal distribution.Notably,the support domain should be large enough to obtain accurate results.This method is then applied for transient analysis of curved shell structures made from functionally graded materials with complex geometries.Through several numerical examples,the accuracy of the proposed approach is demonstrated and discussed.Additionally,the influence of various factors on the dynamic behavior of the structures,including the power-law index,different materials,loading conditions,and geometrical parameters of the structures,was investigated.
基金Science and Technology Plan Project of Xizang Autonomous Region,China under Grant No.XZ202501YD0007。
文摘A novel porous shock absorption layer is put forward in this study, and the shock absorption performance of the porous shock absorption layer is evaluated based on three-dimensional pseudo-static analysis. The modified reaction acceleration method is adopted and validated in the three-dimensional model. Seven ground motions are selected and the peak ground acceleration is adjusted to 0.2 g, 0.4 g and 0.6 g. The impact of the void ratio and thickness of the porous shock absorption layer is studied, while the surrounding rock grade and tunnel depth are also investigated. The numerical results show that the porous shock absorption layer has good shock absorption performance and can effectively reduce the maximum internal force of the secondary lining, but it cannot reduce the maximum horizontal relative displacement of the secondary lining. The circumferential rubber strip in the porous shock absorption layer will reduce shock absorption performance. The results of parameter analysis indicate that the shock absorption performance of the porous shock absorption layer increases with the increase of the void ratio and thickness, and it has good shock absorption performance under different surrounding rock grades and tunnel depths.
文摘BACKGROUND Sagittal spinopelvic alignment(SSA)is essential for preserving a stable and effective upright posture and locomotion.Although alterations in the SSA are recognised to induce compensatory modifications in the pelvis,hips,and knees,the inverse relationship concerning knee pathology undergoing total knee arthroplasty(TKA)has been examined by a limited number of studies,yielding inconclusive results.AIM To generate evidence of the effect of TKA on the SSA from existing literature.METHODS Databases like PubMed,EMBASE,and Scopus were used to identify articles related to the“knee spine syndrome”phenomenon using a combination of subject terms and keywords such as“spinopelvic parameters”,“sagittal spinal balance”,and“total knee arthroplasty”were used with appropriate Boolean operators.Studies measuring the SSA following TKA were included,and research was conducted as per preferred reporting items for systematic review and metaanalysis guidelines.RESULTS A total of 475 participants had undergone TKA,and six studies measuring SSA were analysed.Following TKA,pelvic tilt was the only parameter that showed significant changes,while lumbar lordosis(LL),pelvic incidence,and sacral slope were non-significant,as evident from the forest plots.CONCLUSION The body's sagittal alignment is a complex balance between pelvic,spine,and lower extremity parameters.TKA,while having the potential to correct the flexion contracture,can also correct it.Still,the primary SSA for spinal pathology,i.e.,LL,may not be corrected in patients with co-existent spinal degenerative disease.
基金supported by the National Natural Science Foundation of China(No.32070582)the Joint Foundation of He Lin Academical Workstation of the Third Affiliated Hospital of Guangzhou Medical University(2023HLLH01)the Plan on enhancing scientific research in GMU(2024SRP125).
文摘Investigating the correlation between micronucleus formation and male infertility has the potential to improve clinical diagnosis and deepen our understanding of pathological progression. Our study enrolled 2252 male patients whose semen was analyzed from March 2023 to July 2023. Their clinical data, including semen parameters and age, were also collected. Genetic analysis was used to determine whether the sex chromosome involved in male infertility was abnormal (including the increase, deletion, and translocation of the X and Y chromosomes), and subsequent semen analysis was conducted for clinical grouping purposes. The participants were categorized into five groups: normozoospermia, asthenozoospermia, oligozoospermia, oligoasthenozoospermia, and azoospermia. Patients were randomly selected for further study;41 patients with normozoospermia were included in the control group and 117 patients with non-normozoospermia were included in the study group according to the proportions of all enrolled patients. Cytokinesis-block micronucleus (CBMN) screening was conducted through peripheral blood. Statistical analysis was used to determine the differences in micronuclei (MNi) among the groups and the relationships between MNi and clinical data. There was a significant increase in MNi in infertile men, including those with azoospermia, compared with normozoospermic patients, but there was no significant difference between the genetic and nongenetic groups in azoospermic men. The presence of MNi was associated with sperm concentration, progressive sperm motility, immotile spermatozoa, malformed spermatozoa, total sperm count, and total sperm motility. This study underscores the potential utility of MNi as a diagnostic tool and highlights the need for further research to elucidate the underlying mechanisms of male infertility.
基金supported by the National Key R&D Program of China(2022YFE0200400).
文摘The accurate selection of operational parameters is critical for ensuring the safety,efficiency,and automation of Tunnel Boring Machine(TBM)operations.This study proposes a similarity-based framework integrating model-based boring indexes(derived from rock fragmentation mechanisms)and Euclidean distance analysis to achieve real-time recommendations of TBM operational parameters.Key performance indicators-thrust(F),torque(T),and penetration(p)-were used to calculate three model-based boring indexes(a,b,k),which quantify dynamic rock fragmentation behavior.A dataset of 359 candidate samples,reflecting diverse geological conditions from the Yin-Chao water conveyance project in Inner Mongolia,China,was utilized to validate the framework.The system dynamically recommends parameters by matching real-time data with historical cases through standardized Euclidean distance,achieving high accuracy.Specifically,the mean absolute error(MAE)for rotation speed(n)was 0.10 r/min,corresponding to a mean absolute percentage error(MAPE)of 1.09%.For advance rate(v),the MAE was 3.4 mm/min,with a MAPE of 4.50%.The predicted thrust(F)and torque(T)values exhibited strong agreement with field measurements,with MAEs of 270 kN and 178 kN∙m,respectively.Field applications demonstrated a 30%reduction in parameter adjustment time compared to empirical methods.This work provides a robust solution for real-time TBM control,advancing intelligent tunneling in complex geological environments.
文摘AIM:To analyze the characteristics and correlation of phacoemulsification parameters and anterior segment parameters in cataract patients with different blood glucose levels.METHODS:A total of 45 type 2 diabetic cataract patients(45 eyes)treated in our hospital from March 2023 to April 2024 were stratified into two groups based on glycosylated hemoglobin(HbA1c)levels:group A:HbA1c<7%(n=18)and group B:7%≤HbA1c<8.5%(n=27);a total of 94 age-matched age-related cataract patients(94 eyes)were enrolled as the control group(group C).All underwent phacoemulsification with intraocular lens implantation.Anterior segment parameters,including corneal,lens and anterior chamber measurements,were recorded.Correlations between phacoemulsification parameters and anterior segment parameters were analyzed,and differences among groups were compared.RESULTS:In groups A and B,effective phacoemulsification time(EPT)negatively correlated with corneal endothelial cell density(CECD)(r=-0.315,P=0.035).Average phacoemulsification time(APT)positively correlated with the anterior corneal surface radius of curvature(Rm;r=0.402,P=0.006)and negatively correlated with the flat axis meridian curvature(K 1),steep axis meridian curvature(K 2),mean curvature(Km)of the anterior corneal surface,and lens density at 6 mm zones(PDZ3;all P<0.05).Average phacoemulsification energy(AVE)positively correlated with mean lens density(LD-mean),lens density at 2 mm zones(PDZ1),lens density at 4 mm zones(PDZ2),and PDZ3(all P<0.05),and negatively with pupil diameter(r=-0.385,P=0.009).In the group C,EPT showed a positive correlation with Pentacam nucleus staging(PNS)density grade,PDZ1,PDZ2,and PDZ3(all P<0.05).A positive correlation was observed between AVE and PNS classification(r=0.246,P=0.018).Conversely,AVE exhibited a negative correlation with CECD(r=-0.245,P=0.018).EPT in groups A and B was higher than that in the group C(P<0.05).Both EPT and APT in the group B were higher than those in the group A(P<0.05).In diabetic cataract patients,CECD,corneal density(CD),and posterior corneal surface height positively correlated with diabetes duration(P<0.05).Posterior corneal surface K 1 and Rm positively correlated with 7%≤HbA1c<8.5%(P<0.05).Total corneal astigmatism negatively correlated with HbA1c,2-hour post-breakfast blood glucose(2hPBG),and fasting insulin(FINS;P<0.05).CD and lens thickness(LT)positively correlated with FINS(P<0.05).CONCLUSION:Phacoemulsification parameters and blood glucose-related indices exhibited varying degrees of correlation with anterior segment parameters in cataract patients with different blood glucose levels.EPT in diabetic cataract patients was higher than that in age-related cataract patients,while EPT and APT in diabetic cataract patients with poor glycemic control were higher than those with good glycemic control.
基金funded by the INTER program and cofunded by the Fond National de la Recherche,Luxembourg(FNR)and the Fund for Scientific Research-FNRS,Belgium(F.R.S-FNRS),T.0233.20-‘Sustainable Residential Densification’project(SusDens,2020–2024).
文摘The impact of different global and local variables in urban development processes requires a systematic study to fully comprehend the underlying complexities in them.The interplay between such variables is crucial for modelling urban growth to closely reflects reality.Despite extensive research,ambiguity remains about how variations in these input variables influence urban densification.In this study,we conduct a global sensitivity analysis(SA)using a multinomial logistic regression(MNL)model to assess the model’s explanatory and predictive power.We examine the influence of global variables,including spatial resolution,neighborhood size,and density classes,under different input combinations at a provincial scale to understand their impact on densification.Additionally,we perform a stepwise regression to identify the significant explanatory variables that are important for understanding densification in the Brussels Metropolitan Area(BMA).Our results indicate that a finer spatial resolution of 50 m and 100 m,smaller neighborhood size of 5×5 and 3×3,and specific density classes—namely 3(non-built-up,low and high built-up)and 4(non-built-up,low,medium and high built-up)—optimally explain and predict urban densification.In line with the same,the stepwise regression reveals that models with a coarser resolution of 300 m lack significant variables,reflecting a lower explanatory power for densification.This approach aids in identifying optimal and significant global variables with higher explanatory power for understanding and predicting urban densification.Furthermore,these findings are reproducible in a global urban context,offering valuable insights for planners,modelers and geographers in managing future urban growth and minimizing modelling.
基金National Key R&D Program of China under Grant Nos.2018YFC1504504 and 2018YFC0809404。
文摘Damage to electrical equipment in an earthquake can lead to power outage of power systems.Seismic fragility analysis is a common method to assess the seismic reliability of electrical equipment.To further guarantee the efficiency of analysis,multi-source uncertainties including the structure itself and seismic excitation need to be considered.A method for seismic fragility analysis that reflects structural and seismic parameter uncertainty was developed in this study.The proposed method used a random sampling method based on Latin hypercube sampling(LHS)to account for the structure parameter uncertainty and the group structure characteristics of electrical equipment.Then,logistic Lasso regression(LLR)was used to find the seismic fragility surface based on double ground motion intensity measures(IM).The seismic fragility based on the finite element model of an±1000 kV main transformer(UHVMT)was analyzed using the proposed method.The results show that the seismic fragility function obtained by this method can be used to construct the relationship between the uncertainty parameters and the failure probability.The seismic fragility surface did not only provide the probabilities of seismic damage states under different IMs,but also had better stability than the fragility curve.Furthermore,the sensitivity analysis of the structural parameters revealed that the elastic module of the bushing and the height of the high-voltage bushing may have a greater influence.
文摘This research investigates the influence of indoor and outdoor factors on photovoltaic(PV)power generation at Utrecht University to accurately predict PV system performance by identifying critical impact factors and improving renewable energy efficiency.To predict plant efficiency,nineteen variables are analyzed,consisting of nine indoor photovoltaic panel characteristics(Open Circuit Voltage(Voc),Short Circuit Current(Isc),Maximum Power(Pmpp),Maximum Voltage(Umpp),Maximum Current(Impp),Filling Factor(FF),Parallel Resistance(Rp),Series Resistance(Rs),Module Temperature)and ten environmental factors(Air Temperature,Air Humidity,Dew Point,Air Pressure,Irradiation,Irradiation Propagation,Wind Speed,Wind Speed Propagation,Wind Direction,Wind Direction Propagation).This study provides a new perspective not previously addressed in the literature.In this study,different machine learning methods such as Multilayer Perceptron(MLP),Multivariate Adaptive Regression Spline(MARS),Multiple Linear Regression(MLR),and Random Forest(RF)models are used to predict power values using data from installed PVpanels.Panel values obtained under real field conditions were used to train the models,and the results were compared.The Multilayer Perceptron(MLP)model was achieved with the highest classification accuracy of 0.990%.The machine learning models used for solar energy forecasting show high performance and produce results close to actual values.Models like Multi-Layer Perceptron(MLP)and Random Forest(RF)can be used in diverse locations based on load demand.
基金supported by the National Key R&D Program of China(Grant No.2022YFB4601700).
文摘Serving as the initiating explosive devices between the propellant tank and the engines,metal-based rupture diaphragms are widely used in ramjet igniters owing to the advantages provided by their simple structure,small size,and low cost.However,the reliability of rupture pressure directly affects the success of engine ignition and rocket launch,which is mainly influenced by factors like material,structure,and residual thickness of the surface notch of the diaphragm.Among those,the geometry of the notch is easy to define and control when compared to the mechanical parameters of the ruptured diaphragm.Thus,to make the diaphragm rupture(1A30 Al)within the required pressure range(0.4 MPa±3.5%)with highly sensitive and reliability,we draw inspiration from the arthropod’s force-sensitive slit organ which encompasses curved microgrooves to design a Ω-shaped notch for the rupture diaphragm.Finite element analysis is used to study the relationship between the burst pressure and geometric dimension of theΩ-shaped and bioinspired microgroove.Based on that,metal-based rupture diaphragms are fabricated by femtosecond laser processing technology,followed by rupture tests.Experiment results demonstrate that the practical rupture pressure of the diaphragm is highly consistent with the finite element analysis results,which verifies the effectiveness of the bionic design.
基金support by the Education University of Hong Kong to perform this project under International Grant(UMT/International Grant/2020/53376).
文摘Hydrogen(H_(2))is a promising renewable energy which finds wide applications as the world gears toward low-carbon economy.However,current H_(2) production via steam methane reforming of natural gas or gasification of coal are laden with high CO_(2) footprints.Recently,methane(CH_(4))pyrolysis has emerged as a potential technology to generate low-carbon H_(2) and solid carbon.In this review,the current state-of-art and recent progress of H_(2) production from CH_(4) pyrolysis are reviewed in detail.Aspects such as funda-mental mechanism and chemistry involved,effect of process parameters on the conversion efficiency and reaction kinetics for various reaction media and catalysts are elucidated and critically discussed.Temper-ature,among other factors,plays the most critical influence on the methane pyrolysis reaction.Molten metal/salt could lower the operating temperature of methane pyrolysis to<1000℃,whereas plasma technology usually operates in the regime of>1000℃.Based on the reaction kinetics,metal-based cata-lysts were more efficient in lowering the activation energy of the reaction to 29.5-88 kJ/mol from that of uncatalyzed reaction(147-420.7 kJ/mol).Besides,the current techno-economic performance of the pro-cess reveals that the levelized cost of H_(2) is directly influenced by the sales price of carbon(by-product)generated,which could offset the overall cost.Lastly,the main challenges of reactor design for efficient product separation and retrieval,as well as catalyst deactivation/poisoning need to be debottlenecked.
基金supported by the National Natural Science Foundation of China(Grant No.U21B2075)。
文摘Dynamic analysis of the tethered satellite system(TSS)can provide a fundamental guideline to the evaluation of performance and robust design of the system examined.Uncertainties inherited with the parameters would induce unexpected variation of the response and deteriorate the reliability of the system.In this work,the effect of uncertain mass of the satellites on the deployment and retrieval dynamics of the TSS is investigated.First the interval mode is employed to take the variation of mass of satellite into account in the processes of deployment and retrieval.Then,the Chebyshev interval method is used to obtain the lower and upper response bounds of the TSS.To achieve a smooth and reliable implementation of deployment and retrieval,the nonlinear programming based on the Gauss pseudospectral method is adopted to obtain optimal trajectory of tether velocity.Numerical results show that the uncertainties of mass of the satellites have a distinct influence on the response of tether tension in the processes of deployment and retrieval.
基金Supported by the National Natural Science Foundation of China (51675509)Wenzhou Public Welfare Industrial Technology Project (G20170026).
文摘In order to improve the performance and service life of the Leningrader seal of the Stirling engine piston rod,interference,pre-load and friction coefficient were taken as influencing factors,and the curved surface response method was adopted to reduce the contact stress of sealing surface and von Mises stress of the sealing sleeve as the response index,with the optimization goal of reducing wear and extending life.The above three key parameters are analyzed and optimized,the influence of each parameter on the sealing performance and service life is obtained,and the best combination scheme of the three is determined.The results show that the interaction between pre-tightening force and interference fit has the greatest impact on contact stress.The interaction between interference fit and friction coeffi-cient has the most significant effect on von Mises stress.The optimized parameters can reduce the maximum contact stress and maximum von Mises stress of the sealing sleeve by 26.3%and 20.6%,respectively,under a media pressure of 5-9 MPa.Test bench verification shows that the leakage of the optimized sealing device in 12 h is reduced by 0.44 cc·min^(-1)(1 cc=1 cm^(3)).The wear rate of the sealing sleeve is 1.08%before optimization and 0.45%after optimization,indicating that the optimized parameters in this paper are effective.
文摘Foot-and-mouth disease(FMD)is a viral disease that affects cloven-hoofed animals including cattle,pigs,and sheep,hence causing export bans among others,causing high economic losses due to reduced productivity.The global effect of FMD is most felt where livestock rearing forms an important source of income.It is therefore important to understand the modes of transmission of FMD to control its spread and prevent its occurrence.This work intends to address these dynamics by including the efficacy of active migrant animals transporting the disease from one area to another in a fuzzy mathematical modeling framework.Historical models of epidemics are determinable with a set of deterministic parameters and this does not reflect on real-life scenarios as observed in FMD.Fuzzy theory is used in this model as it permits the inclusion of uncertainties in the model;this makes the model more of a reality regarding disease transmission.A time lag,in this case,denotes the incubation period and other time-related factors affecting the spread of FMD and,therefore,is added to the current model for FMD.To that purpose,the analysis of steady states and the basic reproduction number are performed and,in addition,the stability checks are conveyed in the fuzzy environment.For the numerical solution of the model,we derive the Forward Euler Method and the fuzzy delayed non-standard finite difference(FDNSFD)method.Analytical studies of the FDNSFD scheme are performed for convergence,non-negativity,boundedness,and consistency analysis of the numerical projection to guarantee that the numerical model is an accurate discretization of the continuous dynamics of FMD transmission over time.In the following simulation study,we show that the FDNSFD method preserves the characteristics of the constant model and still works if relatively large time steps are employed;this is a bonus over the normal finite difference technique.The study shows how valuable it is to adopt fuzzy theory and time delays when simulating the transmission of the epidemic,especially for such diseases as FMD where uncertainty and migration have a defining role in transmission.This approach gives more sound and flexible grounds for analyzing and controlling the outbreak of FMD in various situations.
文摘Objectives:The movement towards personalization of cochlear implantation has continued to generate interest about variabilities in cochlear size.In a recent metaanalysis,Atalay et al.(2022)examined organ of corti length,cochlear lateral wall,and“A”value and found that most covariates,other than congenital sensorineural hearing loss,did not impact cochlear size via these measurements.However,no meta-analysis exists on how patient-specific variables could impact other cochlear size measurements,such as cochlear height(CH),and“B”value(defined as the distance between opposite lateral walls and perpendicular to“A”value).The purpose of this systematic review and meta-analysis is to examine how patient-specific variables impact additional cochlear size measurements to assist clinical decisionmaking.Databases reviewed:A systematic review for cochlear size measurements using PRISMA methodology was performed using PubMed,CINAHL,and MEDLINE from database inception to October 1st,2022.Methods:Search terms used included English,cochlea,size,histology,anatomy,and human.Inclusion criteria were measurements for human cochlea,full-text articles,and articles in English.Primary measurements were“B”value and CH,as these measurements differ from the recent meta-analysis on this topic.Cochlear duct length(CDL)was also included.A random-effects continuous model for meta-analysis was performed.Measurements were stratified by gender(male/female)and disease type(sensorineural hearing loss(SNHL)/conductive hearing loss(CHL)).Results:A total of 7 articles met final inclusion criteria from a total of 674 articles received on initial search,resulting in 2263 total human cochleae.There was a statistical difference between male CDL(n=681 cochlea)compared to female CDL(n=657)from four articles(p<0.001;Cohen’s d effect size(ES):0.421;95%confidence intervals(CI):0.171,0.671).The frequency weighted mean for male CDL was 33.5 mm±1.8 mm and the frequency weighted mean for female CDL was 32.4 mm±1.5 mm with an unstandardized mean difference of 0.854 mm.There was no statistical difference between male“B”value(n=329)and female“B”value(n=349)for cochlea from two studies(p=0.184;Cohen’s d ES:0.410;95%CI:0.194,1.014).The frequency weighted mean for male“B”value was 6.5 mm±0.1 mm and the frequency weighted mean for female“B”value was 6.4 mm±0.1 mm with an unstandardized mean difference of 0.126 mm.There was no statistical difference between CH for SNHL(n=282)and CHL(n=275)from two studies(p=0.486;ES:0.085;95%CI:0.323,0.153,F ig.3).The frequency weighted mean for SNHL CH was 4.6 mm±0.8 mm and the frequency weighted mean for CHL CH was 4.3 mm±0.8 mm with an unstandardized mean difference of 0.032 mm.Conclusion:Male CDL is statistically larger than female CDL.There is no statistically significant association between gender or hearing loss type and“B”value or CH.The effect size for all comparisons is small,indicating little practical significance between any existing differences.The results of this study provide two additional cochlear metrics and indicate similar findings to the study by Atalay and colleagues as patient-specific characteristics appear to have no statistically significantly impact on cochlear size.
基金Supported by Shenzhen Science and Technology Program(No.JCYJ20220530153604010).
文摘AIM:To develop a deep learning-based model for automatic retinal vascular segmentation,analyzing and comparing parameters under diverse glucose metabolic status(normal,prediabetes,diabetes)and to assess the potential of artificial intelligence(AI)in image segmentation and retinal vascular parameters for predicting prediabetes and diabetes.METHODS:Retinal fundus photos from 200 normal individuals,200 prediabetic patients,and 200 diabetic patients(600 eyes in total)were used.The U-Net network served as the foundational architecture for retinal arteryvein segmentation.An automatic segmentation and evaluation system for retinal vascular parameters was trained,encompassing 26 parameters.RESULTS:Significant differences were found in retinal vascular parameters across normal,prediabetes,and diabetes groups,including artery diameter(P=0.008),fractal dimension(P=0.000),vein curvature(P=0.003),C-zone artery branching vessel count(P=0.049),C-zone vein branching vessel count(P=0.041),artery branching angle(P=0.005),vein branching angle(P=0.001),artery angle asymmetry degree(P=0.003),vessel length density(P=0.000),and vessel area density(P=0.000),totaling 10 parameters.CONCLUSION:The deep learning-based model facilitates retinal vascular parameter identification and quantification,revealing significant differences.These parameters exhibit potential as biomarkers for prediabetes and diabetes.
基金supported by the National Key R&D Program of China(No.2021YFB0301200)National Natural Science Foundation of China(No.62025208).
文摘Large-scale Language Models(LLMs)have achieved significant breakthroughs in Natural Language Processing(NLP),driven by the pre-training and fine-tuning paradigm.While this approach allows models to specialize in specific tasks with reduced training costs,the substantial memory requirements during fine-tuning present a barrier to broader deployment.Parameter-Efficient Fine-Tuning(PEFT)techniques,such as Low-Rank Adaptation(LoRA),and parameter quantization methods have emerged as solutions to address these challenges by optimizing memory usage and computational efficiency.Among these,QLoRA,which combines PEFT and quantization,has demonstrated notable success in reducing memory footprints during fine-tuning,prompting the development of various QLoRA variants.Despite these advancements,the quantitative impact of key variables on the fine-tuning performance of quantized LLMs remains underexplored.This study presents a comprehensive analysis of these key variables,focusing on their influence across different layer types and depths within LLM architectures.Our investigation uncovers several critical findings:(1)Larger layers,such as MLP layers,can maintain performance despite reductions in adapter rank,while smaller layers,like self-attention layers,aremore sensitive to such changes;(2)The effectiveness of balancing factors depends more on specific values rather than layer type or depth;(3)In quantization-aware fine-tuning,larger layers can effectively utilize smaller adapters,whereas smaller layers struggle to do so.These insights suggest that layer type is a more significant determinant of fine-tuning success than layer depth when optimizing quantized LLMs.Moreover,for the same discount of trainable parameters,reducing the trainable parameters in a larger layer is more effective in preserving fine-tuning accuracy than in a smaller one.This study provides valuable guidance for more efficient fine-tuning strategies and opens avenues for further research into optimizing LLM fine-tuning in resource-constrained environments.
基金the financial support through Beijing Natural Science Foundation(Grant No.3212010)National Natural Science Foundation of China(Grant No.51875031).
文摘The rotor is the most important component of rotating machinery,and the vibration produced by its mass unbalance has a serious influence on the secure and steady operation of the machine,so an effective online suppression technology is urgently needed.A new hydraulic unbalanced bionic self-recovery system is introduced,imitating the way of manually repairing faulty equipment.To accomplish the effect of actuator mass redistribution,the technology employs pressurized air to drive the quantitative transfer of liquid in the reservoir cavity at opposite positions.It can complete the online adjustment of the equipment's balancing state and suppress the unbalanced vibration of equipment in real time,which gives the equipment the ability to maintain an autonomous health state and improve equipment performance.The composition and working principle of the system are introduced in detail,and the key performance parameters,such as the minimum running speed and the balancing liquid transfer speed,are analyzed theoretically.The fluid-solid coupling model of the actuator was established,and the two-phase flow from inside the hydraulic unbalanced bionic self-recovery actuator was simulated under multiple working conditions and the performance parameters were quantitatively analyzed.A balancing simulation test bed was built,and its effectiveness was verified by performance parameter tests and unbalanced bionic self-recovery experiments.The experimental results show that the mass distribution adjustment of the balancing disk can be achieved using different viscosity balancing liquid,and the response of liquid viscosity 10 cSt is faster than that of liquid viscosity 100 cSt in the process of balancing liquid transfer,and the time is reduced by more than 75%;the system can reduce the simulated rotor amplitude from 18.3μm to 10.6μm online in real time,which provides technical support for the subsequent development of a new generation of bionic intelligent equipment.
