期刊文献+
共找到1,282篇文章
< 1 2 65 >
每页显示 20 50 100
Age-and gender-specific dynamics and next-generation reference intervals for pepsinogen in northern China
1
作者 Miao-Miao Zhang Dong Zhu +1 位作者 Hai-Bin Zhao Xiu-Ying Zhao 《World Journal of Gastroenterology》 2025年第31期63-74,共12页
BACKGROUND Pepsinogen(PG)and the PG I/II ratio(PGR)are critical indicators for diagnosing Helicobacter pylori infection and chronic atrophic gastritis,and assessing gastric cancer risk.Existing reference intervals(RIs... BACKGROUND Pepsinogen(PG)and the PG I/II ratio(PGR)are critical indicators for diagnosing Helicobacter pylori infection and chronic atrophic gastritis,and assessing gastric cancer risk.Existing reference intervals(RIs)often overlook age,sex,and demographic variations.Partitioned RIs,while considering these factors,fail to capture the gradual age-related physiological changes.Next-generation RIs offer a solution to this limitation.AIM To investigate age-and sex-specific dynamics of PG and establish next-generation RIs for adults and the elderly in northern China.METHODS After screening,708 healthy individuals were included in this observational study.Serum PG was measured using chemiluminescence immunoassay.Age-and sex-related effects on PG were analyzed with a two-way analysis of variance.RI partitioning was determined by the standard deviation ratio(SDR).Traditional RIs were established using a non-parametric approach.Generalized Additive Models for Location,Scale,and Shape(GAMLSS)modeled age-related trends and continuous reference percentiles for PG I and PG II.Reference limit flagging rates for both RI types were compared.RESULTS PG I and PG II levels were influenced by age(P<0.001)and sex(P<0.001),while PGR remained stable.Age-specific RIs were required for PG I(SDR=0.366)and PG II(SDR=0.424).Partitioned RIs were established for PG I and PG II,with a single RI for PGR.GAMLSS modeling revealed distinct age-dependent trajectories:PG I increased from a median of 39.75μg/L at age 20 years to 49.75μg/L at age 60 years,a 25.16%increase,after which it plateaued through age 80 years.In contrast,PG II showed a continuous rise throughout the age range,with the median value increasing from 5.07μg/L at age 20 years to 8.36μg/L at age 80 years,corresponding to a 64.89%increase.Continuous reference percentiles intuitively reflected these trends and were detailed in this study.Next-generation RIs demonstrated superior accuracy compared to partitioned RIs when applied to specific age subgroups.CONCLUSION This study elucidates the age-and sex-specific dynamics of PG and,to our knowledge,is the first to establish next-generation RIs for PG,supporting more individualized interpretation in laboratory medicine. 展开更多
关键词 PEPSINOGEN Reference intervals Next-generation reference intervals Age dynamics Gastric biomarkers Personalized medicine
暂未订购
A systematic data-driven modelling framework for nonlinear distillation processes incorporating data intervals clustering and new integrated learning algorithm
2
作者 Zhe Wang Renchu He Jian Long 《Chinese Journal of Chemical Engineering》 2025年第5期182-199,共18页
The distillation process is an important chemical process,and the application of data-driven modelling approach has the potential to reduce model complexity compared to mechanistic modelling,thus improving the efficie... The distillation process is an important chemical process,and the application of data-driven modelling approach has the potential to reduce model complexity compared to mechanistic modelling,thus improving the efficiency of process optimization or monitoring studies.However,the distillation process is highly nonlinear and has multiple uncertainty perturbation intervals,which brings challenges to accurate data-driven modelling of distillation processes.This paper proposes a systematic data-driven modelling framework to solve these problems.Firstly,data segment variance was introduced into the K-means algorithm to form K-means data interval(KMDI)clustering in order to cluster the data into perturbed and steady state intervals for steady-state data extraction.Secondly,maximal information coefficient(MIC)was employed to calculate the nonlinear correlation between variables for removing redundant features.Finally,extreme gradient boosting(XGBoost)was integrated as the basic learner into adaptive boosting(AdaBoost)with the error threshold(ET)set to improve weights update strategy to construct the new integrated learning algorithm,XGBoost-AdaBoost-ET.The superiority of the proposed framework is verified by applying this data-driven modelling framework to a real industrial process of propylene distillation. 展开更多
关键词 Integrated learning algorithm Data intervals clustering Feature selection Application of artificial intelligence in distillation industry Data-driven modelling
在线阅读 下载PDF
Role of Folic Acid Supplementation on Association between Short Inter-Pregnancy Intervals and Adverse Birth Outcomes:A Retrospective Cohort Study in Changsha,China
3
作者 Zhiqing Zhao Ling Chen +3 位作者 Wenbin Ouyang Jing Deng Xiaohui Chen Xin Huang 《Biomedical and Environmental Sciences》 2025年第6期751-756,共6页
Preterm birth and suboptimal fetal growth remain significant perinatal challenges worldwide.Recent data indicate that China's perinatal profile has improved due to reductions in preterm birth rates.However,the cou... Preterm birth and suboptimal fetal growth remain significant perinatal challenges worldwide.Recent data indicate that China's perinatal profile has improved due to reductions in preterm birth rates.However,the country has a 6.5%prevalence of small-for-gestational-age(SGA),ranking fifth globally in total SGA birth numbers^([1,2]). 展开更多
关键词 preterm birth short inter pregnancy intervals perinatal profile suboptimal fetal growth folic acid supplementation adverse birth outcomes perinatal challenges
暂未订购
Perceptions and recommendations of multiparas and health-related professionals on appropriate birth intervals:A descriptive qualitative study
4
作者 Hongyan Liu Xinli Zhu +5 位作者 Zhijing Xu Shuang Liang Ya Liu Xiaojiao Wang Xu Qian Chunyi Gu 《International Journal of Nursing Sciences》 2025年第5期469-476,I0003,共9页
Objectives:This study aimed to explore the perceptions and recommendations of multiparas and health-related professionals regarding appropriate birth intervals(Bis)and key determinants.Methods:In-depth semi-structured... Objectives:This study aimed to explore the perceptions and recommendations of multiparas and health-related professionals regarding appropriate birth intervals(Bis)and key determinants.Methods:In-depth semi-structured interviews were conducted between April 1 and June 30,2022.Nine multiparas and thirteen health-related professionals were purposefully sampled until data saturation was reached.A thematic analysis approach was applied to the interview transcripts,utilizing dual independent coding and consensus validation in NVivo 12.0.Results:The data generated two overarching categories:1)balanced decision-making on the appropriate birth intervals and 2)internal and external determinants integrated with health and societal considerations.Four key themes emerged following the two categories:1)consistency and discrepancy between the actual and recommended birth intervals of multiparas;2)health-and developmentoriented professional recommendations;3)internal determinants related to individual-level factors;and 4)external determinants related to child-related factors,family support,and social security.Weighing women's reproductive health and career development,multiparas and health-related professionals perceived a length between 18 and 36 months as the appropriate Bl.Conclusion:Multiparas and health-related professionals shaped their balanced recommendations on a relatively appropriate birth interval ranging from 18 to 36 months,which was influenced by women's individual-level factors,child-related factors,family support,and social security.Targeted social and healthcare services should be offered to women and their families during the Bls. 展开更多
关键词 Birth interval Health personnel MULTIPARA Perception Risk factor
暂未订购
Towards improved neonatal care:Developing reference intervals for biochemical parameters in umbilical cord blood:An Indian study
5
作者 Keyur Sabnis Swati Ghanghurde +2 位作者 Akash Shukla Dhriti Sukheja Mohit Vijay Rojekar 《World Journal of Clinical Pediatrics》 2025年第4期340-347,共8页
BACKGROUND The reference ranges for biochemical parameters can fluctuate due to factors like altitude,age,gender,and socioeconomic conditions.These values are crucial for interpreting laboratory data and guide clinica... BACKGROUND The reference ranges for biochemical parameters can fluctuate due to factors like altitude,age,gender,and socioeconomic conditions.These values are crucial for interpreting laboratory data and guide clinical treatment decisions.Currently,there is no established set of reference intervals for cord blood biochemical parameters of newborns in India,particularly in Mumbai.AIM To create cord blood biochemical parameters reference intervals specifically for Mumbai,India.METHODS A cross-sectional study was conducted in an Indian tertiary care hospital.This study focused on healthy newborns with normal birth weight,born to pregnant mothers without health issues.Cord blood samples,approximately 2-3 mL in volume,were collected from 210 term neonates.These samples were divided into fluoride(glucose)and clot activator(serum)tubes and were subsequently analyzed in the institute's biochemical laboratory.The data obtained from the analysis was then subjected to statistical analysis.The result of the Shapiro-Wilk test suggested non-normality in the data distribution.Consequently,nonparametric statistics were utilized for analysis.The Mann-Whitney U test was utilized to compare parameter distributions among different factors,including the infant’s sex,delivery method,maternal age,and obstetric history.A significance level of P<0.05 was considered to indicate statistical significance.RESULTS The following represent the median figures and central 95 percentile reference intervals for biochemical parameters in umbilical cord blood of newborns:Serum direct bilirubin=(0.1-0.55)mg/dL,indirect bilirubin=(0.64-2.26)mg/dL,total bilirubin=(0.62-3.14)mg/dL,creatinine=(0.27-0.76)mg/dL,sodium=(128.19-143.26)mmol/L,chloride=(100.19-111.68)mmol/L,potassium=(1.62-9.98)mmol/L and plasma glucose=(24.75-94.23)mg/dL.Statistically significant differences were observed in serum sodium,potassium,and plasma glucose levels when comparing delivery modes.CONCLUSION This is the pioneering study in which first time,the biochemical reference intervals in cord blood for newborns are established in western India.The values are applicable for newborns from this area.Larger study throughout the country is required. 展开更多
关键词 Biochemical Parameters Reference interval Umbilical cord blood Peripheral venous blood NEONATES INDIA
暂未订购
Confidence Intervals for the Reliability of Dependent Systems:Integrating Frailty Models and Copula-Based Methods
6
作者 Osnamir E.Bru-Cordero Cecilia Castro +1 位作者 Victor Leiva Mario C.Jaramillo-Elorza 《Computer Modeling in Engineering & Sciences》 2025年第5期1401-1431,共31页
Most reliability studies assume large samples or independence among components,but these assump-tions often fail in practice,leading to imprecise inference.We address this issue by constructing confidence intervals(CI... Most reliability studies assume large samples or independence among components,but these assump-tions often fail in practice,leading to imprecise inference.We address this issue by constructing confidence intervals(CIs)for the reliability of two-component systems with Weibull distributed failure times under a copula-frailty framework.Our construction integrates gamma-distributed frailties to capture unobserved heterogeneity and a copula-based dependence structure for correlated failures.The main contribution of this work is to derive adjusted CIs that explicitly incorporate the copula parameter in the variance-covariance matrix,achieving near-nominal coverage probabilities even in small samples or highly dependent settings.Through simulation studies,we show that,although traditional methods may suffice with moderate dependence and large samples,the proposed CIs offer notable benefits when dependence is strong or data are sparse.We further illustrate our construction with a synthetic example illustrating how penalized estimation can mitigate the issue of a degenerate Hessian matrix under high dependence and limited observations,so enabling uncertainty quantification despite deviations from nominal assumptions.Overall,our results fill a gap in reliability modeling for systems prone to correlated failures,and contribute to more robust inference in engineering,industrial,and biomedical applications. 展开更多
关键词 Censored data copula methods dependent failure times interval estimation Weibull distribution
在线阅读 下载PDF
Multi-Timescale Optimization Scheduling of Distribution Networks Based on the Uncertainty Intervals in Source-Load Forecasting
7
作者 Huanan Yu Chunhe Ye +3 位作者 Shiqiang Li He Wang Jing Bian Jinling Li 《Energy Engineering》 2025年第6期2417-2448,共32页
With the increasing integration of large-scale distributed energy resources into the grid,traditional distribution network optimization and dispatch methods struggle to address the challenges posed by both generation ... With the increasing integration of large-scale distributed energy resources into the grid,traditional distribution network optimization and dispatch methods struggle to address the challenges posed by both generation and load.Accounting for these issues,this paper proposes a multi-timescale coordinated optimization dispatch method for distribution networks.First,the probability box theory was employed to determine the uncertainty intervals of generation and load forecasts,based on which,the requirements for flexibility dispatch and capacity constraints of the grid were calculated and analyzed.Subsequently,a multi-timescale optimization framework was constructed,incorporating the generation and load forecast uncertainties.This framework included optimization models for dayahead scheduling,intra-day optimization,and real-time adjustments,aiming to meet flexibility needs across different timescales and improve the economic efficiency of the grid.Furthermore,an improved soft actor-critic algorithm was introduced to enhance the uncertainty exploration capability.Utilizing a centralized training and decentralized execution framework,a multi-agent SAC network model was developed to improve the decision-making efficiency of the agents.Finally,the effectiveness and superiority of the proposed method were validated using a modified IEEE-33 bus test system. 展开更多
关键词 Renewable energy distribution networks source-load uncertainty interval flexible scheduling soft actor-critic algorithm optimization model
在线阅读 下载PDF
Gray relational analysis and SBOA-BP for predicting settlement intervals of high-speed railway subgrade
8
作者 Quanpeng He Shaoyuan Li 《Railway Sciences》 2025年第2期199-212,共14页
Purpose–The deformation of the roadbed is easily influenced by the external environment to improve the accuracy of high-speed railway subgrade settlement prediction.Design/methodology/approach–A high-speed railway s... Purpose–The deformation of the roadbed is easily influenced by the external environment to improve the accuracy of high-speed railway subgrade settlement prediction.Design/methodology/approach–A high-speed railway subgrade settlement interval prediction method using the secretary bird optimization(SBOA)algorithm to optimize the BP neural network under the premise of gray relational analysis is proposed.Findings–Using the SBOA algorithm to optimize the BP neural network,the optimal weights and thresholds are obtained,and the best parameter prediction model is combined.The data were collected from the sensors deployed through the subgrade settlement monitoring system,and the gray relational analysis is used to verify that all four influencing factors had a great correlation to the subgrade settlement,and the collected data are verified using the model.Originality/value–The experimental results show that the SBOA-BP model has higher prediction accuracy than the BP model,and the SBOA-BP model has a wider range of prediction intervals for a given confidence level,which can provide higher guiding value for practical engineering applications. 展开更多
关键词 Gray relational analysis Secretary bird optimization algorithm Backpropagation neural network Subgrade settlement Interval prediction
在线阅读 下载PDF
Vibrotactile pattern recognition:Influence of interstimulus intervals
9
作者 Nashmin YEGANEH Ivan MAKAROV +1 位作者 Arni KRISTJANSSON Runar UNNTHORSSON 《虚拟现实与智能硬件(中英文)》 2025年第5期483-500,共18页
Background Vibrotactile feedback systems are widely used in assistive technology,wearable devices,and virtual environments to deliver precise tactile information.The timing of interstimulus intervals(ISIs)plays a crit... Background Vibrotactile feedback systems are widely used in assistive technology,wearable devices,and virtual environments to deliver precise tactile information.The timing of interstimulus intervals(ISIs)plays a critical role in determining how accurately users perceive and interpret vibrotactile patterns.The optimal use of ISIs can increase the effectiveness of these systems,improve user interaction,and enable reliable,intuitive feedback in diverse applications.We examined how different interstimulus intervals ISIs impact the accuracy of vibrotactile pattern recognition.Methods Participants wore a forearm-mounted device with six voice coil actuators arranged in a 3×2 grid,delivering Braille-based vibrotactile patterns sequentially at ISIs ranging from 10 to 2500 ms.Eight participants performed identification tasks involving Icelandic Braille patterns categorized as either short(2-3 actuators)or long(4-5 actuators).A repeated measures ANOVA was conducted to assess the effects of ISI,pattern type,and practice(across two testing blocks)on pattern recognition accuracy.Results For short patterns,accuracy was highest(92%-98%)at ISIs of 50-700 ms,with peak performance at 300 ms.For long patterns,accuracy reached 86%-94%at ISIs of 100-500 ms,peaking at 400 ms.Participants were more accurate with short patterns,and performance improved significantly over time for both short and long patterns,highlighting the importance of training for vibrotactile pattern recognition.Conclusions These results underscore the importance of careful selection of ISIs in vibrotactile feedback systems for accurate pattern identification.The findings provide valuable insights for conveying tactile information using wearable devices,contributing to better tactile feedback and performance in applications requiring precise vibrotactile information delivery. 展开更多
关键词 Voice coil actuator Wearable vibrotactile device Vibratory stimulus Vibrotactile localization Vibrotactile frequency Vibrotactile discrimination Interstimulus Interval(ISI)
暂未订购
Positive Solutions of Second Order Discrete Problem on Infinite Intervals
10
作者 Haiyi WU Tianlan CHEN 《Journal of Mathematical Research with Applications》 CSCD 2024年第4期511-520,共10页
In this paper,by using the discrete Arzelá-Ascoli Lemma and the fixed-point theorem in cones,we discuss the existence of positive solutions of the following second order discrete Sturm-Liouville boundary value pr... In this paper,by using the discrete Arzelá-Ascoli Lemma and the fixed-point theorem in cones,we discuss the existence of positive solutions of the following second order discrete Sturm-Liouville boundary value problem on infinite intervals■where Δu(x)=u(x+1)-u(x)is the forward difference operator,■is continuous,a>0,B and C are nonnegative constants. 展开更多
关键词 positive solutions second order discrete problems infinite intervals fixed-point theorem in cones
原文传递
Low-Carbon Dispatch of an Integrated Energy System Considering Confidence Intervals for Renewable Energy Generation
11
作者 Yan Shi Wenjie Li +2 位作者 Gongbo Fan Luxi Zhang Fengjiu Yang 《Energy Engineering》 EI 2024年第2期461-482,共22页
Addressing the insufficiency in down-regulation leeway within integrated energy systems stemming from the erratic and volatile nature of wind and solar renewable energy generation,this study focuses on formulating a c... Addressing the insufficiency in down-regulation leeway within integrated energy systems stemming from the erratic and volatile nature of wind and solar renewable energy generation,this study focuses on formulating a coordinated strategy involving the carbon capture unit of the integrated energy system and the resources on the load storage side.A scheduling model is devised that takes into account the confidence interval associated with renewable energy generation,with the overarching goal of optimizing the system for low-carbon operation.To begin with,an in-depth analysis is conducted on the temporal energy-shifting attributes and the low-carbon modulation mechanisms exhibited by the source-side carbon capture power plant within the context of integrated and adaptable operational paradigms.Drawing from this analysis,a model is devised to represent the adjustable resources on the charge-storage side,predicated on the principles of electro-thermal coupling within the energy system.Subsequently,the dissimilarities in the confidence intervals of renewable energy generation are considered,leading to the proposition of a flexible upper threshold for the confidence interval.Building on this,a low-carbon dispatch model is established for the integrated energy system,factoring in the margin allowed by the adjustable resources.In the final phase,a simulation is performed on a regional electric heating integrated energy system.This simulation seeks to assess the impact of source-load-storage coordination on the system’s low-carbon operation across various scenarios of reduction margin reserves.The findings underscore that the proactive scheduling model incorporating confidence interval considerations for reduction margin reserves effectively mitigates the uncertainties tied to renewable energy generation.Through harmonized orchestration of source,load,and storage elements,it expands the utilization scope for renewable energy,safeguards the economic efficiency of system operations under low-carbon emission conditions,and empirically validates the soundness and efficacy of the proposed approach. 展开更多
关键词 Integrated energy system carbon capture power plant confidence interval optimized scheduling
在线阅读 下载PDF
Short-term oxidation behavior of powder metallurgy Al_(0.8)Co_(0.5)Cr_(1.5)CuFeNi HEA in high-temperature solid and semi-solid intervals
12
作者 Minjie Huang Jufu Jiang +3 位作者 Ying Wang Yingze Liu Ying Zhang Jian Dong 《Journal of Materials Science & Technology》 CSCD 2024年第26期116-131,共16页
In this work,possible short-term thermal exposure oxidation in hot processing including semi-solid processing is focused.We aim to investigate the short-term oxidation behavior of a novel powder metallurgy Al_(0.8)Co_... In this work,possible short-term thermal exposure oxidation in hot processing including semi-solid processing is focused.We aim to investigate the short-term oxidation behavior of a novel powder metallurgy Al_(0.8)Co_(0.5)Cr_(1.5)CuFeNi high entropy alloy(HEA)in high-temperature solid(1000-1100℃)and semi-solid(1125-1225℃)intervals.From 1000 to 1225℃,mass gain increases from 0.31 to 0.45 mg cm^(-2)after 60 min oxidation,presenting superior oxidation resistance in the semi-solid state compared with other semi-solid alloys.Equiaxedα-Al_(2)O_(3)grains are the predominant component of oxide scales and no obvious internal oxidation layer occurs in both solid and semi-solid intervals.Al_(2)O_(3)scale growth is predominantly determined by outward Al^(3+)diffusion.For solid oxidation,different scale formation kinetics occur on various phases and the BCC(B2)phase has faster scale formation kinetics.This is attributed to outward Al^(3+)diffusion rate differences in various component systems.During semi-solid oxidation,the increased degree of chaos and number of vacancies in the liquid phase provide a diffusion channel,leading to rapid Al_(2)O_(3)formation.Oxidation resistance in the semi-solid state is attributed to dense Al_(2)O_(3)scales formed through selective oxidation of Al. 展开更多
关键词 High entropy alloy Short-term oxidation Semi-solid interval Oxidation behavior Oxidation resistance
原文传递
Analysis of petrophysical cutoffs of reservoir intervals with production capacity and with accumulation capacity in clastic reservoirs 被引量:4
13
作者 Wang Yanzhong Cao Yingchang +3 位作者 Song Guoqi Song Ling Yang Tian Zhang Shaomin 《Petroleum Science》 SCIE CAS CSCD 2014年第2期211-219,共9页
Methodologies have been developed for calculating cutoffs of reservoir intervals with production capacity (RIPC) and reservoir intervals with accumulation capacity (RIAC) according to the types of pore throat stru... Methodologies have been developed for calculating cutoffs of reservoir intervals with production capacity (RIPC) and reservoir intervals with accumulation capacity (RIAC) according to the types of pore throat structures and dynamic force by using data from petrophysical analysis, production tests and mercury injection. The data are from clastic reservoirs in the third member (Es3) and the fourth member (Es4) of the Shahejie Formation in the Shengtuo area on the North Slope of the Dongying Sag, Jiyang Depression, China. The method of calculating cutoffs of RIPC is summarized as follows: 1) determination of permeability cutoffs of RIPC; 2) classification of types of pore-throat structures according to mercury injection data and then relating porosity to permeability and determining the relationship between porosity and permeability according to each type of pore-throat structure; and 3) calculating porosity cutoffs of RIPC using established correlation between porosity and permeability according to the type of pore throat structure. The method of calculating cutoffs of RIAC includes: 1) establishing a functional relationship between oil-water interracial tension and formation temperature; 2) calculating limiting values of maximum connected pore-throat radii according to formation temperature and dynamic forces of each reservoir interval; 3) correlating permeability with maximum connected pore-throat radius and then obtaining permeability cutoffs of RIAC; and 4) calculating porosity cutoffs on the basis of permeability cutoffs according to specific correlations, suitable for the type of porethroat structure. The results of this study show that porosity and permeability cutoffs of clastic reservoirs decrease with depth. For a fixed permeability cutoff, the porosity cutoff of R1PC varies because the type of pore throat is different. At a fixed temperature, porosity and permeability cutoffs of RIAC decrease as dynamic force increases. For a fixed permeability cutoff of effective hydrocarbon accumulation, the porosity cutoff also varies with different types of pore throat. 展开更多
关键词 Effective reservoir petrophysical cutoff of reservoir intervals with production capacity(RIPC) petrophysical cutoff of reservoir intervals with accumulation capacity (RIAC) clastic rocks
原文传递
Optimizing the microstructures and mechanical properties of Al-Cu-based alloys with large solidification intervals by coupling travelling magnetic fields with sequential solidification 被引量:3
14
作者 Lei Luo Liangshun Luo +6 位作者 Robert O.Ritchie Yanqing Su Binbin Wang Liang Wang Ruirun Chen Jingjie Guo Hengzhi Fu 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2021年第2期100-113,共14页
Alloys with large solidification intervals are prone to issues from the disordered growth and defect formation;accordingly, finding ways to effectively optimize the microstructure, further to improve the mechanical pr... Alloys with large solidification intervals are prone to issues from the disordered growth and defect formation;accordingly, finding ways to effectively optimize the microstructure, further to improve the mechanical properties is of great importance. To this end, we couple travelling magnetic fields with sequential solidification to continuously regulate the mushy zones of Al-Cu-based alloys with large solidification intervals. Moreover, we combine experiments with simulations to comprehensively analyze the mechanisms on the optimization of microstructure and properties. Our results indicate that only downward travelling magnetic fields coupled with sequential solidification can obtain the refined and uniform microstructure, and promote the growth of matrix phase -Al along the direction of temperature gradient.Additionally, the secondary dendrites and precipitates are reduced, while the solute partition coefficient and solute solid-solubility are raised. Ultimately, downward travelling magnetic fields can increase the ultimate tensile strength, yield strength, elongation and hardness from 196.2 MPa, 101.2 MPa, 14.5 % and85.1 kg mm-2 without travelling magnetic fields to 224.1 MPa, 114.5 MPa, 17.1 % and 102.1 kg mm-2,and improve the ductility of alloys. However, upward travelling magnetic fields have the adverse effects on microstructural evolution, and lead to a reduction in the performance and ductility. Our findings demonstrate that long-range directional circular flows generated by travelling magnetic fields directionally alter the transformation and redistribution of solutes and temperature, which finally influences the solidification behavior and performance. Overall, our research present not only an innovative method to optimize the microstructures and mechanical properties for alloys with large solidification intervals,but also a detailed mechanism of travelling magnetic fields on this optimization during the sequential solidification. 展开更多
关键词 Large solidification intervals Travelling magnetic fields Sequential solidification Mushy zones Al-Cu-based alloys
原文传递
Assessment of Impacts of Public Health Interventions on the SARS Epidemic in Beijing in Terms of the Intervals Between Its Symptom Onset, Hospital Admission, and Notification 被引量:3
15
作者 WAN-NIANLIANG MINLIU +3 位作者 ZE-JUNLIU XIONGHE YUEPAN XUE-QINXIE 《Biomedical and Environmental Sciences》 SCIE CAS CSCD 2005年第3期153-158,共6页
Objectives To assess the impacts of public health interventions on the outbreak of SARS in Beijing by analyzing the intervals between symptom onset, hospital admission and notification of its cases. Methods Data of SA... Objectives To assess the impacts of public health interventions on the outbreak of SARS in Beijing by analyzing the intervals between symptom onset, hospital admission and notification of its cases. Methods Data of SARS cases reported from the Beijing Municipal Centers for Disease Prevention and Control (BCDC) were collected and analyzed by descriptive epidemiology. Results In the early epidemic period, the intervals between the disease onset and the hospital admission seemed irregular, so was the intervals between the hospital admission and the notification. After the middle ten days of April, the intervals turned out to be more regular, and the disordered situation in terms of the hospital admission and the case notification was gradually brought under control. Conclusions Public health interventions against SARS has revealed positive impacts on SARS control program in Beijing. The timing and sensitivity of epidemic information reporting systems has been greatly improved in Beijing as a result of successful fight against this disease. 展开更多
关键词 SARS intervals Interventions IMPACTS
暂未订购
Reducing porosity and optimizing performance for Al-Cu-based alloys with large solidification intervals by coupling travelling magnetic fields with sequential solidification 被引量:2
16
作者 Lei Luo Liangshun Luo +5 位作者 Yanqing Su Lin Su Liang Wang Ruirun Chen Jingjie Guo Hengzhi Fu 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2021年第20期1-14,共14页
Porosity is a major casting defect in alloys with large solidification intervals due to the disordered microstructure and broad mushy zones,which decreases badly the mechanical performance.Hence,finding ways to effect... Porosity is a major casting defect in alloys with large solidification intervals due to the disordered microstructure and broad mushy zones,which decreases badly the mechanical performance.Hence,finding ways to effectively reduce the porosity,further to optimize microstructure and mechanical performance is of great significance.In this regard,the Al-Cu-based alloys with large solidification intervals are continuously processed by coupling the travelling magnetic fields(TMF)with sequential solidification.Additionally,experiments combined with simulations are utilized to comprehensively analyze the mechanism of TMF on the reduction in porosity,including shrinkage porosity and gas porosity,from different perspectives.Current findings determine that downward TMF can effectually optimize together the porosity,microstructure and performance,by inducing the strong long-range directional melt flows,stabilizing the mushy zones,and optimizing the feeding channels and exhaust paths,as well as increasing the driving force of degassing process.Eventually,downward TMF can increase the ultimate tensile strength,yield strength,elongation and hardness from 175.2 MPa,87.5 MPa,13.3%and 80.2 kg mm^(-2) without TMF to 218.6 MPa,109.3 MPa,15.6%and 95.5 kg mm^(-2),while reduce the total porosity from0.95%to 0.18%.However,Up-TMF exerts negative effects on the optimization of porosity,microstructure and performance due to the opposite strong directional magnetic force and melt flows.Overall,our study provides an effective way to optimize together the porosity,microstructure and mechanical performance,and reveals their relationship,as well as details the relevant mechanisms of TMF on the porosity reduction from different perspectives. 展开更多
关键词 POROSITY Large solidification intervals Travelling magnetic fields Sequential solidification Al-Cu-based alloys
原文传递
Variational Inference Based Kernel Dynamic Bayesian Networks for Construction of Prediction Intervals for Industrial Time Series With Incomplete Input 被引量:2
17
作者 Long Chen Linqing Wang +2 位作者 Zhongyang Han Jun Zhao Wei Wang 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2020年第5期1437-1445,共9页
Prediction intervals(PIs)for industrial time series can provide useful guidance for workers.Given that the failure of industrial sensors may cause the missing point in inputs,the existing kernel dynamic Bayesian netwo... Prediction intervals(PIs)for industrial time series can provide useful guidance for workers.Given that the failure of industrial sensors may cause the missing point in inputs,the existing kernel dynamic Bayesian networks(KDBN),serving as an effective method for PIs construction,suffer from high computational load using the stochastic algorithm for inference.This study proposes a variational inference method for the KDBN for the purpose of fast inference,which avoids the timeconsuming stochastic sampling.The proposed algorithm contains two stages.The first stage involves the inference of the missing inputs by using a local linearization based variational inference,and based on the computed posterior distributions over the missing inputs the second stage sees a Gaussian approximation for probability over the nodes in future time slices.To verify the effectiveness of the proposed method,a synthetic dataset and a practical dataset of generation flow of blast furnace gas(BFG)are employed with different ratios of missing inputs.The experimental results indicate that the proposed method can provide reliable PIs for the generation flow of BFG and it exhibits shorter computing time than the stochastic based one. 展开更多
关键词 Industrial time series kernel dynamic Bayesian networks(KDBN) prediction intervals(PIs) variational inference
在线阅读 下载PDF
Determination of reference intervals for metabolic profile of Hanwoo cows at early, middle and late gestation periods 被引量:1
18
作者 Da Chuan Piao Tao Wang +4 位作者 Jae Sung Lee Renato SA Vega Sang Ki Kang Yun Jaie Choi Hong Gu Lee 《Journal of Animal Science and Biotechnology》 SCIE CAS CSCD 2015年第2期252-256,共5页
Background: Metabolic profile was initially designed as a presymptomatic diagnostic aid based on statistical analyses of blood metabolites to provide an early warning of certain types of metabolic disorder. However, ... Background: Metabolic profile was initially designed as a presymptomatic diagnostic aid based on statistical analyses of blood metabolites to provide an early warning of certain types of metabolic disorder. However, there is little metabolic profile data available about Korean Hanwoo cows. Therefore, this study aimed to determine the reference intervals of metabolic profile for Korean Hanwoo cows. Methods: Healthy animals (2,205) were selected and divided into early (day 1 to 95), middle (day 96 to 190) and late (day 191 to 285) period according to their gestating period. Metabolic profile including total protein (TP), albumin (AIb), urea (UREA), glucose (Glu), total cholesterol (T-Cho), long-chain fatty acid (LCFA), aspartate aminotransferase (AST), gamma-glutamyl transpeptidase (GGT), creatinine (Crea), calcium (Ca), inorganic phosphorous (iP) and magnesium (Mg) were analyzed using a TBA-4OFR automatic biochemical analyzer. The data of Korean Hanwoo cows were then compared to those of the Japanese Wagyu cows. Results: Most of the data of the Korean Hanwoo cows were relatively higher than those of Japanese Wagyu cows, with the exception of Glu and GGT. This may indicate that the nutritional level of feed for the Korean Hanwoo cows was higher than that of the Japanese Wagyu cows because of the different feeding system. In particular, relatively higher levels of UREA and LCFA were observed in the Korean Hanwoo cows, and this may also contribute to the low reproduction efficiency. Conclusions: These findings may provide some theoretical basis for understanding the reproductive and feeding situation of Korean Hanwoo cows. 展开更多
关键词 Hanwoo cows Metabolic profile Reference intervals Wagyu cows
在线阅读 下载PDF
Sequencing Mixed-Model Flexible Assembly Lines with Variable Launching Intervals 被引量:1
19
作者 童科娜 徐克林 郑永前 《Journal of Shanghai Jiaotong university(Science)》 EI 2013年第4期460-467,共8页
To solve the sequencing problem in mixed-model flexible assembly lines (MMFALs) with variable launching intervals, a mathematical model aiming to minimize the cost of utility and idle times is developed. To obtain hig... To solve the sequencing problem in mixed-model flexible assembly lines (MMFALs) with variable launching intervals, a mathematical model aiming to minimize the cost of utility and idle times is developed. To obtain high-quality sequences, an advanced scatter search (ASS) algorithm is proposed. A heuristic approach, i.e. launching intervals between products algorithm (LIBPA), is incorporated into the ASS algorithm to solve the launching interval problem for each sequence. Numerical experiments with different scales are conducted to compare the performance of ASS with genetic algorithm (GA). In addition, we compare the cost of variable launching intervals approach with fixed launching intervals approach. The results indicate that the ASS is efficient and effective, and considering variable launching intervals in mixed-model assembly lines (MMALs) sequencing problem can improve the performance of the line. 展开更多
关键词 variable launching intervals mixed-model assembly line (MMAL) FLEXIBLE SEQUENCING scatter search algorithm
原文传递
Indirect determination of serum creatinine reference intervals in a Pakistani pediatric population using big data analytics 被引量:2
20
作者 Sibtain Ahmed Jakob Zierk +1 位作者 Imran Siddiqui Aysha Habib Khan 《World Journal of Clinical Pediatrics》 2021年第4期72-78,共7页
BACKGROUND The indirect methods of reference intervals(RI)establishment based on data mining are utilized to overcome the ethical,practical challenges and the cost associated with the conventional direct approach.AIM ... BACKGROUND The indirect methods of reference intervals(RI)establishment based on data mining are utilized to overcome the ethical,practical challenges and the cost associated with the conventional direct approach.AIM To generate RIs for serum creatinine in children and adolescents using an indirect statistical tool.METHODS Data mining of the laboratory information system was performed for serum creatinine analyzed from birth to 17 years for both genders.The timeline was set at six years from January 2013 to December 2018.Microsoft Excel 2010 and an indirect algorithm developed by the German Society of Clinical Chemistry and Laboratory Medicine’s Working Group on Guide Limits were used for the data analysis.RESULTS Data were extracted from 96104 samples and after excluding multiple samples for the same individual,we calculated RIs for 21920 males and 14846 females,with stratification into six discrete age groups.CONCLUSION Serum creatinine dynamics varied significantly across gender and age groups. 展开更多
关键词 CREATININE PEDIATRIC Reference intervals Indirect Data mining Pakistan
暂未订购
上一页 1 2 65 下一页 到第
使用帮助 返回顶部