期刊文献+
共找到1,640篇文章
< 1 2 82 >
每页显示 20 50 100
Meridional Distributions of Historical Zonal Averages and Their Use to Quantify the Global and Spheroidal Mean Near-Surface Temperature of the Terrestrial Atmosphere 被引量:1
1
作者 Gerhard Kramm Martina Berger +1 位作者 Ralph Dlugi Nicole Molders 《Natural Science》 2020年第3期80-124,共45页
The zonal averages of temperature (the so-called normal temperatures) for numerous parallels of latitude published between 1852 and 1913 by Dove, Forbes, Ferrel, Spitaler, Batchelder, Arrhenius, von Bezold, Hopfner, v... The zonal averages of temperature (the so-called normal temperatures) for numerous parallels of latitude published between 1852 and 1913 by Dove, Forbes, Ferrel, Spitaler, Batchelder, Arrhenius, von Bezold, Hopfner, von Hann, and B&ouml;rnstein were used to quantify the global (spherical) and spheroidal mean near-surface temperature of the terrestrial atmosphere. Only the datasets of Dove and Forbes published in the 1850s provided global averages below 〈T〉=14°C, mainly due to the poor coverage of the Southern Hemisphere by observations during that time. The global averages derived from the distributions of normal temperatures published between 1877 and 1913 ranged from 〈T〉=14.0°C (Batchelder) to 〈T〉=15.1°C (Ferrel). The differences between the global and the spheroidal mean near-surface air temperature are marginal. To examine the uncertainty due to interannual variability and different years considered in the historic zonal mean temperature distributions, the historical normal temperatures were perturbed within ±2σ to obtain ensembles of 50 realizations for each dataset. Numerical integrations of the perturbed distributions indicate uncertainties in the global averages in the range of ±0.3°C to ±0.6°C and depended on the number of available normal temperatures. Compared to our results, the global mean temperature of 〈T〉=15.0°C published by von Hann in 1897 and von Bezold in 1901 and 1906 is notably too high, while 〈T〉=14.4°C published by von Hann in 1908 seems to be more adequate within the range of uncertainty. The HadCRUT4 record provided 〈T〉≌?13.7°C for 1851-1880 and 〈T〉=13.6°C for 1881-1910. The Berkeley record provided 〈T〉=13.6°C and 〈T〉≌?13.5°C for these periods, respectively. The NASA GISS record yielded 〈T〉=13.6°C for 1881-1910 as well. These results are notably lower than those based on the historic zonal means. For 1991-2018, the HadCRUT4, Berkeley, and NASA GISS records provided 〈T〉=14.4°C, 〈T〉=14.5°C, and 〈T〉=14.5°C, respectively. The comparison of the 1991-2018 globally averaged near-surface temperature with those derived from distributions of zonal temperature averages for numerous parallels of latitude suggests no change for the past 100 years. 展开更多
关键词 Global Mean Temperature Spheroidal Mean Temperature Climatological Mean Values for the Parallels of Latitude Zonal averages Normal Temperature Temperature Anomaly Isothermal Charts Solar Climate
在线阅读 下载PDF
More on half-wormholes and ensemble averages
2
作者 Jia Tian Yingyu Yang 《Communications in Theoretical Physics》 SCIE CAS CSCD 2023年第9期1-21,共21页
We continue our study Half-Wormholes and Ensemble Averages about the half-wormhole proposal.By generalizing the original proposal of the half-wormhole,we propose a new way to detect half-wormholes.The crucial idea is ... We continue our study Half-Wormholes and Ensemble Averages about the half-wormhole proposal.By generalizing the original proposal of the half-wormhole,we propose a new way to detect half-wormholes.The crucial idea is to decompose the observables into self-averaged sectors and non-self-averaged sectors.We find the contributions from different sectors have interesting statistics in the semi-classical limit.In particular,dominant sectors tend to condense and the condensation explains the emergence of half-wormholes and we expect that the appearance of condensation is a signal of possible bulk description.We also initiate the study of multi-linked half-wormholes using our approach. 展开更多
关键词 half-wormholes factorization problem quantum gravity ensemble averages SYK
原文传递
Generalized Sampling Series Approximation of Random Signals from Local Averages
3
作者 宋占杰 何改云 +1 位作者 叶培新 杨德运 《Transactions of Tianjin University》 EI CAS 2007年第1期8-11,共4页
Signals are often of random character since they cannot bear any information if they are predictable for any time t, they are usually modelled as stationary random processes .On the other hand, because of the inertia ... Signals are often of random character since they cannot bear any information if they are predictable for any time t, they are usually modelled as stationary random processes .On the other hand, because of the inertia of the measurement apparatus, measured sampled values obtained in practice may not be the precise value of the signal X(t) at time tk (k∈Z), but only local averages of X(t) near tk. In this paper, it is presented that a wide (or weak ) sense stationary stochastic process can be approximated by generalized sampling series with local average samples. 展开更多
关键词 stochastic processes local averages generalized sampling series
在线阅读 下载PDF
Randomly Weighted Averages on Order Statistics
4
作者 Homei Hajir Hasanzadeh Leila Mina Ghasemi 《Applied Mathematics》 2013年第9期1340-1346,共7页
We study a well-known problem concerning a random variable uniformly distributed between two independent random variables. Two different extensions, randomly weighted average on independent random variables and random... We study a well-known problem concerning a random variable uniformly distributed between two independent random variables. Two different extensions, randomly weighted average on independent random variables and randomly weighted average on order statistics, have been introduced for this problem. For the second method, two-sided power random variables have been defined. By using classic method and power technical method, we study some properties for these random variables. 展开更多
关键词 Two-Sided POWER MOMENT WEIGHTED averages POWER DISTRIBUTION
在线阅读 下载PDF
Smoothing GNSS Time Series with Asymmetric Simple Moving Averages
5
作者 Jose Nuno Lima Joao Casaca 《Journal of Civil Engineering and Architecture》 2012年第6期745-750,共6页
There is an increasing trend to apply GNSS continuous observation of short baselines to the monitoring of engineering works, such as bridges and dams, for their structural analysis and safety control. In the case of l... There is an increasing trend to apply GNSS continuous observation of short baselines to the monitoring of engineering works, such as bridges and dams, for their structural analysis and safety control. In the case of large dams, one important application of the GNSS continuous observation is thc establishment of early warning systems that demand accurate, frequently updated information and where the analysis of the baseline time series, in order to separate signal from noise is mandatory. The paper presents a study on the performance of linear filters of the asymmetric moving average type to smooth baseline time series. The transfer function of the filter is adopted as a smoothing criterion to choose an adequate order for the moving average, in face of the spectral density function of the baseline time series. Onc series of measurements of a short test baseline (325 m), materialized in the campus of the National Laboratory for Civil Engineering, is used as an example of the proposed strategy. 展开更多
关键词 GNSS moving averages spectral density.
在线阅读 下载PDF
Dirichlet Averages, Fractional Integral Operators and Solution of Euler-Darboux Equation on Hölder Spaces
6
作者 D. N. Vyas 《Applied Mathematics》 2016年第14期1498-1503,共7页
In the present paper, we discuss the solution of Euler-Darboux equation in terms of Dirichlet averages of boundary conditions on H?lder space and weighted H?lder spaces of continuous functions using Riemann-Liouville ... In the present paper, we discuss the solution of Euler-Darboux equation in terms of Dirichlet averages of boundary conditions on H?lder space and weighted H?lder spaces of continuous functions using Riemann-Liouville fractional integral operators. Moreover, the results are interpreted in alternative form. 展开更多
关键词 Fractional Integral Operators Dirichlet averages Hölder Space
在线阅读 下载PDF
CONVERGENCE OF WEIGHTED AVERAGES OF MARTINGALES IN NONCOMMUTATIVE BANACH FUNCTION SPACES 被引量:4
7
作者 张超 侯友良 《Acta Mathematica Scientia》 SCIE CSCD 2012年第2期735-744,共10页
Let x (xn)≥1 be a martingale on a noncommutative probability space n (M, r) and (wn)n≥1 a sequence of positive numbers such that Wn = ∑ k=1^n wk →∞ as n →∞ We prove that x = (x.)n≥1 converges in E(M... Let x (xn)≥1 be a martingale on a noncommutative probability space n (M, r) and (wn)n≥1 a sequence of positive numbers such that Wn = ∑ k=1^n wk →∞ as n →∞ We prove that x = (x.)n≥1 converges in E(M) if and only if (σn(x)n≥1 converges in E(.hd), where E(A//) is a noncommutative rearrangement invariant Banach function space with the Fatou property and σn(x) is given by σn(x) = 1/Wn ∑k=1^n wkxk, n=1, 2, .If in addition, E(Ad) has absolutely continuous norm, then, (an(x))≥1 converges in E(.M) if and only if x = (Xn)n≥1 is uniformly integrable and its limit in measure topology x∞∈ E(M). 展开更多
关键词 Weighted average noncommutative martingales noncommutative BanachfunCtion spaces uniform integrability
在线阅读 下载PDF
Danger Detection during Fight against Compartment-Fire Using Moving Averages in Temperature Recordings
8
作者 Michel Lebey Amal Bouaoud Eloi Lambert 《World Journal of Engineering and Technology》 2014年第3期36-41,共6页
In compartment fires (houses, buildings, underground, warehouse, etc.), smokes are a major dan- ger during firemen intervention. Most of the time, they are at high temperature (>800?C) and they flow everywhere thro... In compartment fires (houses, buildings, underground, warehouse, etc.), smokes are a major dan- ger during firemen intervention. Most of the time, they are at high temperature (>800?C) and they flow everywhere through many kinds of ducts, which leads to the propagation of the combustion by the creation other fires in places which may be far away from the initial fire. In this paper, we present a new approach of the problem, which allows to better follow the fire behavior and especially to detect the dangers that may appear and endanger firefighters. This approach consists in a mathematical analysis based on the comparison of moving averages centered in the past, calculated on the temperature recordings of the smokes. As a consequence, this method may allow to improve decision support in real time and therefore to improve the security and the efficiency of firefighters in their operations against that kind of fires. 展开更多
关键词 COMPARTMENT FIRE Decision Support in Real Time Moving Average DANGER DETECTION
暂未订购
Approximation of weak sense stationary stochastic processes from local averages 被引量:7
9
作者 Zhan-jie SONG Wen-chang SUN +1 位作者 Shou-yuan YANG Guang-wen ZHU 《Science China Mathematics》 SCIE 2007年第4期457-463,共7页
We show that a weak sense stationary stochastic process can be approximated by local averages. Explicit error bounds are given. Our result improves an early one from Splettst?sser.
关键词 sampling theorem weak sense stationary stochastic processes local averages average sampling 42C15 60G10 94A20
原文传递
Uniform Truncation Error for Shannon Sampling Expansion from Local Averages 被引量:2
10
作者 Zhan-jie SONG Pei-xin YE +1 位作者 Ping WANG Shou-zhen ZENG 《Acta Mathematicae Applicatae Sinica》 SCIE CSCD 2015年第1期121-130,共10页
Let B^pΩ,1≤Р≤∞,be the set of all bounded functions in L^p(R)which can be extended to entire unctions of exponential typeΩ. The unitbrm bounds for truncation error of Shannon sampling expansion fromlocal averag... Let B^pΩ,1≤Р≤∞,be the set of all bounded functions in L^p(R)which can be extended to entire unctions of exponential typeΩ. The unitbrm bounds for truncation error of Shannon sampling expansion fromlocal averages are obtained for functions f∈BpΩwith the decay condition f(t)≤A/t^δ,t≠0,where A and δare positive constants. Furthermore we also establish similar results for non-bandlimit functions in Besov classes with the same decay condition as above. 展开更多
关键词 Shannon sampling Theorem local averages truncation error modulus of continuity
原文传递
Divergent trends in the burden of esophageal,gastric,and liver cancers in China 被引量:1
11
作者 Yongjie Xu Changfa Xia +2 位作者 Jiachen Wang Yujie Wu Wanqing Chen 《Journal of the National Cancer Center》 2025年第3期306-312,共7页
Background While China’s socioeconomic transformation has driven divergent trends in gastrointestinal cancers,comprehensive data on esophageal,gastric,and liver cancer burden remain limited.This study examines the gl... Background While China’s socioeconomic transformation has driven divergent trends in gastrointestinal cancers,comprehensive data on esophageal,gastric,and liver cancer burden remain limited.This study examines the global burden of esophageal,gastric,and liver cancers in 2022 and analyzes the trends of age-standardized incidence and mortality rate(ASRs)in China from 2000 to 2018,thereby providing evidence for the formulation of cancer control strategies.Methods The global burden of esophageal,gastric and liver cancers including the estimated number of cases and deaths and the ASRs for incidence and mortality were from GLOBALCAN 2022 dataset.Data from 22 cancer registries in China were employed for the trend analysis of the ASRs for incidence and mortality of these three cancers.The Joinpoint model was used to compute the average annual percentage change(AAPC)of the incidence and mortality of the three cancers from 2000 to 2018.Results Globally,esophageal,gastric and liver cancers accounted for 11.8%of incident cancer cases and 19.1%of cancer deaths.China bore a disproportionately high burden,representing 43.8%,37.0%,and 42.4%of global esophageal,gastric,and liver cancer cases respectively,and 42.1%,39.4%,and 41.7%of corresponding deaths.However,the ASRs for incidence and mortality for all three cancers declined significantly in China(2000–2018),with absolute case numbers decreasing for gastric and esophageal cancers during 2010–2022.Age-specific analysis revealed most pronounced declines in incidence and mortality in populations under 40 years old,with AAPCs of less than–6.0%for esophageal cancer,around–4.0%for gastric cancer,and approximately–2.0%for liver cancer.Conclusions China has achieved remarkable progress in controlling esophageal,gastric and liver cancers,yet these malignancies remain major public health challenges.Future efforts should intensify existing prevention measures while expanding screening programs,particularly for aging populations.These findings offer valuable insights for regions undergoing similar epidemiological transitions. 展开更多
关键词 Esophageal cancer Gastric cancer Liver cancer Global burden TRENDS Average annual percent change
暂未订购
Providing Robust and Low-Cost Edge Computing in Smart Grid:An Energy Harvesting Based Task Scheduling and Resource Management Framework 被引量:1
12
作者 Xie Zhigang Song Xin +1 位作者 Xu Siyang Cao Jing 《China Communications》 2025年第2期226-240,共15页
Recently,one of the main challenges facing the smart grid is insufficient computing resources and intermittent energy supply for various distributed components(such as monitoring systems for renewable energy power sta... Recently,one of the main challenges facing the smart grid is insufficient computing resources and intermittent energy supply for various distributed components(such as monitoring systems for renewable energy power stations).To solve the problem,we propose an energy harvesting based task scheduling and resource management framework to provide robust and low-cost edge computing services for smart grid.First,we formulate an energy consumption minimization problem with regard to task offloading,time switching,and resource allocation for mobile devices,which can be decoupled and transformed into a typical knapsack problem.Then,solutions are derived by two different algorithms.Furthermore,we deploy renewable energy and energy storage units at edge servers to tackle intermittency and instability problems.Finally,we design an energy management algorithm based on sampling average approximation for edge computing servers to derive the optimal charging/discharging strategies,number of energy storage units,and renewable energy utilization.The simulation results show the efficiency and superiority of our proposed framework. 展开更多
关键词 edge computing energy harvesting energy storage unit renewable energy sampling average approximation task scheduling
在线阅读 下载PDF
Simulation of light environment in a serrated photovoltaic greenhouse and optimization of daylighting roofs based on Design Builder
13
作者 LIU Jian WU Xuyong +2 位作者 WANG Baolong WU Qingsen TIAN Libo 《农业工程学报》 北大核心 2025年第7期211-221,共11页
In the tropical regions represented by Hainan,there are abundant solar and thermal resources,and it is relatively suitable for the construction of photovoltaic greenhouse(PVG).However,the construction of PVG still rel... In the tropical regions represented by Hainan,there are abundant solar and thermal resources,and it is relatively suitable for the construction of photovoltaic greenhouse(PVG).However,the construction of PVG still relies mainly on experience and is incapable of quantifying the balance between the photovoltaic(PV)generation and the light requirements for agricultural production.As a result,actual PVGs are primarily PV-based,without carefully considering the needs of agricultural daylighting.To quantify the influence of the design parameters of PVGs and the layout of PV panels on the internal daylighting of serrated PVGs,and to optimize the daylighting design of the roof,this paper utilizes the Design Builder software to establish gradient models for a multi-span serrated-type PVG in tropical regions.Gradient models were established in terms of aspects,namely span,width of longitudinal/transverse daylighting strip,height,roof angle,and photovoltaic panel coverage rate(PCR).Daylighting in the greenhouse of each gradient model was simulated,and with the annual average daily light integral(A_(DLI))and distribution uniformity(DU)as evaluation indicators,the influence of various design parameters on the daylighting inside the greenhouse was quantified.The result reveals that:(1)PCR is the decisive indicator for daylighting in the PVG,and a function between PCR and the A_(DLI) is derived as A_(DLI)=-15.5 PCR+16.841;(2)Increasing the width of longitudinal daylighting strip significantly improves the A_(DLI) and enhances DU while increasing the span has a noticeable effect on improving A_(DLI) but does not significantly enhance DU;(3)Increasing the eave height without changing PCR does not enhance A_(DLI) but effectively improves DU;increasing the transverse daylighting strip and adjusting the roof angle hardly improves A_(DLI).In summary,it is recommended that the optimal span for PVGs in tropical regions be set within the range of 6.5-8.0m,and the eave height be set within the range of 2.5-3.5m.Preferably,the longitudinal daylighting strip with a width ranging from 0.5-0.8m should be installed.Based on the above relationship function,the PCR can be calculated according to the appropriate light demand for the cultivated crops.The daylighting design theory proposed in this paper can provide a theoretical basis and reference for the healthy development of the PV industry in tropical regions. 展开更多
关键词 photovoltaic greenhouse annual average daily light integral greenhouse design parameters DAYLIGHTING tropical regions
在线阅读 下载PDF
Gender differences in the burden of near vision loss in China:An analysis based on GBD 2021 data
14
作者 LIU Yu ZHU Liping +4 位作者 LIN Yanhui WANG Yanbing XIONG Kun LI Xuhong YAN Wenguang 《中南大学学报(医学版)》 北大核心 2025年第6期1030-1041,共12页
Objective:Near vision loss(NVL)is one of the leading causes of visual impairment worldwide,exerting a profound impact on individual quality of life and socio-economic development.This study aims to analyze the burden ... Objective:Near vision loss(NVL)is one of the leading causes of visual impairment worldwide,exerting a profound impact on individual quality of life and socio-economic development.This study aims to analyze the burden of NVL in China by sex and age groups from 1990 to 2021 and to project trends over the next 15 years.Methods:Using data from the Global Burden of Disease(GBD)2021 database,we conducted descriptive analyses of NVL prevalence in China,calculated age-standardized prevalence rates(ASPR)and age-standardized disability-adjusted life years rates(ASDR)to compare burden differences between sexes and age groups,and applied an autoregressive integrated moving average(ARIMA)model to predict NVL trends for the next 15 years.The model selection was based on best-fit criteria to ensure reliable projections.Results:From 1990 to 2021,China’s ASPR of NVL rose from 10096.24/100000 to 15624.54/100000,and ASDR increased from 101.75/100000 to 158.75/100000.In 2021,ASPR(16551.70/100000)and ASDR(167.69/100000)were higher among females than males(14686.21/100000 and 149.76/100000,respectively).China ranked highest globally in both NVL cases and disability-adjusted life years(DALYs),with female burden significantly exceeding male burden.Projections indicated this trend and sex gap will persist until 2036.Compared with 1990,the prevalence cases and DALYs increased by 239.20%and 238.82%,respectively in 2021,with the highest burden among females and the 55−59 age group.The ARIMA model predicted continued increases in prevalence and DALYs by 2036,with females maintaining a higher burden than males.Conclusion:This study reveals a marked increase in the NVL burden in China and predicts continued growth in the coming years.Public health policies should prioritize NVL prevention and control,with special attention to women and middle-aged populations to mitigate long-term societal and health impacts. 展开更多
关键词 China near vision loss Global Burden of Disease database autoregressive integrated moving average model gender differences
暂未订购
ON NEW STRATEGIES TO CONTROL THE ACCURACY OF WENO ALGORITHM CLOSE TO DISCONTINUITIES Ⅱ:CELL AVERAGES AND MULTIRESOLUTION
15
作者 Sergio Amat Juan Ruiz Chi-Wang Shu 《Journal of Computational Mathematics》 SCIE CSCD 2020年第4期661-682,共22页
This paper is the second part of the article and is devoted to the construction and analysis of new non-linear optimal weights for WENO interpolation capable of rising the order of accuracy close to discontinuities fo... This paper is the second part of the article and is devoted to the construction and analysis of new non-linear optimal weights for WENO interpolation capable of rising the order of accuracy close to discontinuities for data discretized in the cell averages.Thus,now we are interested in analyze the capabilities of the new algorithm when working with functions belonging to the subspace L1\L2 and that,consequently,are piecewise smooth and can present jump discontinuities.The new non-linear optimal weights are redesigned in a way that leads to optimal theoretical accuracy close to the discontinuities and at smooth zones.We will present the new algorithm for the approximation case and we will analyze its accuracy.Then we will explain how to use the new algorithm in multiresolution applications for univariate and bivariate functions.The numerical results confirm the theoretical proofs presented. 展开更多
关键词 WENO Cell averages New optimal weights Multiresolution schemes Im-proved adaption to discontinuities Signal processing
原文传递
Analysis of phacoemulsification parameters and anterior segment parameters in cataract patients with different blood glucose levels
16
作者 Xu Xinqi Wang Ping +5 位作者 Liu Tong Wang Lei Zhu Xuansheng Zhang Huiwen Shi Lei Gao Wen 《国际眼科杂志》 2025年第6期875-885,共11页
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
关键词 diabetic cataract effective phacoemulsification time average phacoemulsification energy average phacoemulsification time anterior segment parameter
暂未订购
Mass spectrometry for non-destructive detection of the average diameter of micro copper wires
17
作者 Rui Su Xiaowei Fang +5 位作者 Peng Zeng Yong Qian Xuanzhu Li Huiyu Xing Jiamei Lin Jiaquan Xu 《Chinese Chemical Letters》 2025年第10期474-477,共4页
The performance and price of copper-based micro linear products are determined by the diameter uniformity.How to accurately detect the wire diameter of long-length copper based micro linear products without cutting or... The performance and price of copper-based micro linear products are determined by the diameter uniformity.How to accurately detect the wire diameter of long-length copper based micro linear products without cutting or damage has always been a technical concern for production enterprises.Herein,a novel approach was developed for nondestructive detection of the average diameter at any given segment of a long copper wire by assessing the adsorption capacity of arginine on its surface.The amount of adsorbent on the surface of the copper wire exhibits a positive correlation with the area,which can be detected by extractive electrospray ionization mass spectrometry(EESI-MS)after online elution with ammonia.The experimental results demonstrated that the analysis can be completed within 15 min,with a good linear relationship between copper wires with different diameters and the adsorption capacity of arginine.The linear correlation coefficient R2was 0.995,the relative standard deviation was 1.10%-2.81%,and the detection limit reached 2.5μm(length of segment=4 cm),showing potential applications for facile measurement of the average diameter of various metal wires. 展开更多
关键词 Measurement of diameter Mass spectrometry Non-destructive detection Copper wire Average diameter Measurement of diameter Mass spectrometry Non-destructive detection Copper wire Average diameter
原文传递
Inertial-Wave Regime of AveragedThermal Convection in a Rotating Vertical Flat Layer
18
作者 Kirill Rysin Alexey Vjatkin Victor Kozlov 《Fluid Dynamics & Materials Processing》 2025年第3期605-621,共17页
Thermal vibrational convection(TVC)refers to the time-averaged convection of a non-isothermal fluid subjected to oscillating force fields.It serves as an effective mechanism for heat transfer control,particularly unde... Thermal vibrational convection(TVC)refers to the time-averaged convection of a non-isothermal fluid subjected to oscillating force fields.It serves as an effective mechanism for heat transfer control,particularly under microgravity conditions.A key challenge in this field is understanding the effect of rotation on TVC,as fluid oscillations in rotating systems exhibit unique and specific characteristics.In this study,we examine TVC in a vertical flat layer with boundaries at different temperatures,rotating around a horizontal axis.The distinctive feature of this study is that the fluid oscillations within the cavity are not induced by vibrations of the cavity itself,but rather by the gravity field,giving them a tidal nature.Our findings reveal that inertial waves generated in the rotating layer qualitatively alter the TVC structure,producing time-averaged flows in the form of toroidal vortices.Experimental investigations of the structure of oscillatory and time-averaged flows,conducted using Particle Image Velocimetry(PIV)for flow velocity visualization,are complemented by theoretical calculations of inertial modes in a cavity with this geometry.To the best of our knowledge,this study represents the first of its kind.The agreement between experimental results and theoretical predictions confirms that the formation of convective structures in the form of toroidal vortices is driven by inertial waves induced by the gravity field.A decrease in the rotational velocity leads to a transformation of the convective structures,shifting from toroidal vortices of inertial-wave origin to classical cellular TVC.We present dimensionless parameters that define the excitation thresholds for both cellular convection and toroidal structures. 展开更多
关键词 Rotation inertial modes OSCILLATIONS heat transfer stability averaged convection
在线阅读 下载PDF
Dynamic analysis of asymmetric piecewise linear systems
19
作者 Ruiliang ZHANG Yongjun SHEN Xiaotong YANG 《Applied Mathematics and Mechanics(English Edition)》 2025年第4期633-646,共14页
Piecewise linear systems are prevalent in engineering practice,and can be categorized into symmetric and asymmetric piecewise linear systems.Considering that symmetry is a special case of asymmetry,it is essential to ... Piecewise linear systems are prevalent in engineering practice,and can be categorized into symmetric and asymmetric piecewise linear systems.Considering that symmetry is a special case of asymmetry,it is essential to investigate the broader model,namely the asymmetric piecewise linear system.The traditional averaging method is frequently used for studying nonlinear systems,particularly symmetric piecewise linear systems,with the harmonic response of the oscillator serving as a key prerequisite for calculating steady-state solutions.However,asymmetric systems inherently exhibit nonharmonic,asymmetric responses,rendering the traditional averaging method inapplicable.To overcome this limitation,this paper introduces an improved averaging method tailored for an oscillator characterized by asymmetric gaps and springs.Unlike the traditional method,which assumes a purely harmonic response,the improved averaging method redefines the system response as a superposition of a direct current(DC)term and a first harmonic component.Herein,the DC term can be regarded as the offset induced by model asymmetry.Furthermore,the DC term is treated as a slow variable function of time,with its time derivative assumed to be zero when calculating the steady-state solution,akin to the amplitude and phase in the traditional averaging method.Numerical validation demonstrates that the responses computed in both time and frequency domains with the improved averaging method exhibit greater accuracy compared with those derived from the traditional method.Leveraging these improved results,the study also examines the parameter effect,stability,and bifurcation phenomena within the amplitude-frequency responses. 展开更多
关键词 nonlinear vibration piecewise linear system asymmetry averaging method OFFSET
在线阅读 下载PDF
Enhancing clinical and public health interpretation of accelerometer-assessed physical activity with age-referenced values based on UK Biobank data
20
作者 Alex V.Rowlands Andrew P.Kingsnorth +10 位作者 Bjørge H.Hansen Stuart J.Fairclough Lynne M.Boddy Benjamin D.Maylor Henrik R.Eckmann Borja del Pozo Cruz Nathan P.Dawkins Cameron Razieh Kamlesh Khunti Francesco Zaccardi Tom Yates 《Journal of Sport and Health Science》 2025年第1期27-37,共11页
Background Higher accelerometer-assessed volume and intensity of physical activity(PA)have been associated with a longer life expectancy but can be difficult to translate into recommended doses of PA.We aimed to:(a)im... Background Higher accelerometer-assessed volume and intensity of physical activity(PA)have been associated with a longer life expectancy but can be difficult to translate into recommended doses of PA.We aimed to:(a)improve interpretability by producing UK Biobank age-referenced centiles for PA volume and intensity;(b)inform public-health messaging by examining how adding recommended quantities of moderate and vigorous PA affect PA volume and intensity.Methods 92,480 UK Biobank participants aged 43-80 years with wrist-worn accelerometer data were included.Average acceleration and intensity gradient were derived as proxies for PA volume and intensity.We generated sex-specific centile curves using Generalized Additive Models for Location Scale and Shape(GAMLSS)and modeled the effect of adding moderate(walking)or vigorous(running)activity on the combined change in the volume and intensity centiles(change in PA profile).Results In men,volume was lower as age increased while intensity was lower after age 55;in women,both volume and intensity were lower as age increased.Adding 150 min of moderate PA weekly(5×30 min walking)increased the PA profile by 4 percentage points.Defining moderate PA as brisk walking approximately doubled the increase(9 percentage points)while 75 min of vigorous PA weekly(5×15 min running)trebled the increase(13 percentage points).Conclusion These UK Biobank reference centiles provide a benchmark for interpretation of accelerometer data.Application of our translational methods demonstrate that meeting PA guidelines through shorter duration vigorous activity is more beneficial to the PA profile(volume and intensity)than longer duration moderate activity. 展开更多
关键词 Physical activity recommendations Average acceleration Intensity gradient MODERATE Vigorous
在线阅读 下载PDF
上一页 1 2 82 下一页 到第
使用帮助 返回顶部