期刊文献+
共找到2,126篇文章
< 1 2 107 >
每页显示 20 50 100
The UNIFORM C^(0)ESTIMATE AND WEIGHTED ESTIMATE OF GENERALIZED CHRISTOFFEL-MINKOWSKI PROBLEMS
1
作者 ZHANG Jin-hu 《数学杂志》 2024年第5期397-405,共9页
In this paper,we consider generalized Christo®el-Minkowski problems as followsσ_(k)(u_(ij)+uδ_(ij))/σ_(l)(u_(ij)+uδ_(ij))=|u^(p-1)f(x),x∈S^(n),where 0≤l≤k≤n,p-1>0 and f is positive,and we establish the... In this paper,we consider generalized Christo®el-Minkowski problems as followsσ_(k)(u_(ij)+uδ_(ij))/σ_(l)(u_(ij)+uδ_(ij))=|u^(p-1)f(x),x∈S^(n),where 0≤l≤k≤n,p-1>0 and f is positive,and we establish the weighted gradient estimate and uniform C^(0)estimate for the positive convex even solutions,which is a generalization of Guan-Xia[1]and Guan[2]. 展开更多
关键词 weighted gradient estimate convex solution minkowski type problem
下载PDF
Parameter Estimation of a Valve-Controlled Cylinder System Model Based on Bench Test and Operating Data Fusion
2
作者 Deying Su Shaojie Wang +3 位作者 Haojing Lin Xiaosong Xia Yubing Xu Liang Hou 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2024年第2期247-263,共17页
The accurate estimation of parameters is the premise for establishing a high-fidelity simulation model of a valve-controlled cylinder system.Bench test data are easily obtained,but it is challenging to emulate actual ... The accurate estimation of parameters is the premise for establishing a high-fidelity simulation model of a valve-controlled cylinder system.Bench test data are easily obtained,but it is challenging to emulate actual loads in the research on parameter estimation of valve-controlled cylinder system.Despite the actual load information contained in the operating data of the control valve,its acquisition remains challenging.This paper proposes a method that fuses bench test and operating data for parameter estimation to address the aforementioned problems.The proposed method is based on Bayesian theory,and its core is a pool fusion of prior information from bench test and operating data.Firstly,a system model is established,and the parameters in the model are analysed.Secondly,the bench and operating data of the system are collected.Then,the model parameters and weight coefficients are estimated using the data fusion method.Finally,the estimated effects of the data fusion method,Bayesian method,and particle swarm optimisation(PSO)algorithm on system model parameters are compared.The research shows that the weight coefficient represents the contribution of different prior information to the parameter estimation result.The effect of parameter estimation based on the data fusion method is better than that of the Bayesian method and the PSO algorithm.Increasing load complexity leads to a decrease in model accuracy,highlighting the crucial role of the data fusion method in parameter estimation studies. 展开更多
关键词 Valve-controlled cylinder system Parameter estimation The Bayesian theory Data fusion method weight coefficients
下载PDF
LEAST SQUARES ESTIMATION FOR ORNSTEIN-UHLENBECK PROCESSES DRIVEN BY THE WEIGHTED FRACTIONAL BROWNIAN MOTION 被引量:3
3
作者 申广君 尹修伟 闫理坦 《Acta Mathematica Scientia》 SCIE CSCD 2016年第2期394-408,共15页
In this article, we study a least squares estimator (LSE) of θ for the Ornstein- Uhlenbeck process X0=0,dXt=θXtdt+dBt^ab, t ≥ 0 driven by weighted fractional Brownian motion B^a,b with parameters a, b. We obtain... In this article, we study a least squares estimator (LSE) of θ for the Ornstein- Uhlenbeck process X0=0,dXt=θXtdt+dBt^ab, t ≥ 0 driven by weighted fractional Brownian motion B^a,b with parameters a, b. We obtain the consistency and the asymptotic distribution of the LSE based on the observation {Xs, s∈[0,t]} as t tends to infinity. 展开更多
关键词 weighted fractional Brownian motion least squares estimator Ornstein-Uhl-enbeck process
下载PDF
Recursive weighted least squares estimation algorithm based on minimum model error principle 被引量:2
4
作者 雷晓云 张志安 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2021年第2期545-558,共14页
Kalman filter is commonly used in data filtering and parameters estimation of nonlinear system,such as projectile's trajectory estimation and control.While there is a drawback that the prior error covariance matri... Kalman filter is commonly used in data filtering and parameters estimation of nonlinear system,such as projectile's trajectory estimation and control.While there is a drawback that the prior error covariance matrix and filter parameters are difficult to be determined,which may result in filtering divergence.As to the problem that the accuracy of state estimation for nonlinear ballistic model strongly depends on its mathematical model,we improve the weighted least squares method(WLSM)with minimum model error principle.Invariant embedding method is adopted to solve the cost function including the model error.With the knowledge of measurement data and measurement error covariance matrix,we use gradient descent algorithm to determine the weighting matrix of model error.The uncertainty and linearization error of model are recursively estimated by the proposed method,thus achieving an online filtering estimation of the observations.Simulation results indicate that the proposed recursive estimation algorithm is insensitive to initial conditions and of good robustness. 展开更多
关键词 Minimum model error weighted least squares method State estimation Invariant embedding method Nonlinear recursive estimate
下载PDF
ERRATUM TO: LEAST SQUARES ESTIMATION FOR ORNSTEIN-UHLENBECK PROCESSES DRIVEN BY THE WEIGHTED FRACTIONAL BROWNIAN MOTION (ACTA MATHEMATICA SCIENTIA 2016,36B (2) :394-408) 被引量:1
5
作者 申广君 尹修伟 闫理坦 《Acta Mathematica Scientia》 SCIE CSCD 2017年第4期1173-1176,共4页
We give a correction of Theorem 2.2 of Shen, Yin and Yan (2016).
关键词 weighted fractional Brownian motion least squares estimator Ornstein-Uhlenbeck process
下载PDF
Wavelet Density Estimation and Statistical Evidences Role for a GARCH Model in the Weighted Distribution 被引量:1
6
作者 Mohammad Abbaszadeh Mahdi Emadi 《Applied Mathematics》 2013年第2期410-416,共7页
We consider n observations from the GARCH-type model: Z = UY, where U and Y are independent random variables. We aim to estimate density function Y where Y have a weighted distribution. We determine a sharp upper boun... We consider n observations from the GARCH-type model: Z = UY, where U and Y are independent random variables. We aim to estimate density function Y where Y have a weighted distribution. We determine a sharp upper bound of the associated mean integrated square error. We also make use of the measure of expected true evidence, so as to determine when model leads to a crisis and causes data to be lost. 展开更多
关键词 Density estimation GARCH Model weighted Distribution WAVELETS Statistical Evidences STRONGLY MIXING
下载PDF
Generalized weighted functional proportional mean combining forecasting model and its method of parameter estimation
7
作者 万玉成 盛昭潮 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2004年第1期7-11,18,共6页
A new kind of combining forecasting model based on the generalized weighted functional proportional mean is proposed and the parameter estimation method of its weighting coefficients by means of the algorithm of quadr... A new kind of combining forecasting model based on the generalized weighted functional proportional mean is proposed and the parameter estimation method of its weighting coefficients by means of the algorithm of quadratic programming is given. This model has extensive representation. It is a new kind of aggregative method of group forecasting. By taking the suitable combining form of the forecasting models and seeking the optimal parameter, the optimal combining form can be obtained and the forecasting accuracy can be improved. The effectiveness of this model is demonstrated by an example. 展开更多
关键词 combining forecasting generalized weighted functional proportional mean parameter estimation quadratic programming
下载PDF
STUDY ON FREQUENCY ESTIMATION BASED ON WEIGHTED LEAST SQUARE METHOD WITH THREE FOURIER COEFFICIENTS
8
作者 Ren Chunhui Fu Yusheng 《Journal of Electronics(China)》 2013年第5期430-435,共6页
In this paper,a sinusoidal signal frequency estimation algorithm is proposed by weighted least square method.Based on the idea of Provencher,three biggest Fourier coefficients in the maximum periodogram are considered... In this paper,a sinusoidal signal frequency estimation algorithm is proposed by weighted least square method.Based on the idea of Provencher,three biggest Fourier coefficients in the maximum periodogram are considered,the Fourier coefficients can be written as three equations about the amplitude,phase,and frequency,and the frequency is estimated by solving equations.Because of the error of measurement,weighted least square method is used to solve the frequency equation and get the signal frequency.It is shown that the proposed estimator can approach the Cramer-Rao Bound(CRB)with a low Signal-to-Noise Ratio(SNR)threshold and has a higher accuracy. 展开更多
关键词 Sinusoidal signal Frequency estimation Fourier coefficients weighted least square method
下载PDF
Weighted Likelihood Estimation Method Based on the Multidimensional Nominal Response Model
9
作者 孙珊珊 陶剑 《Northeastern Mathematical Journal》 CSCD 2008年第3期250-256,共7页
The Monte Carlo study evaluates the relative accuracy of Warm's (1989) weighted likelihood estimate (WLE) compared to the maximum likelihood estimate (MLE) using the nominal response model. And the results indi... The Monte Carlo study evaluates the relative accuracy of Warm's (1989) weighted likelihood estimate (WLE) compared to the maximum likelihood estimate (MLE) using the nominal response model. And the results indicate that WLE was more accurate than MLE. 展开更多
关键词 weighted likelihood estimation item response model nominal response model
下载PDF
Intention Estimation of Adversarial Spatial Target Based on Fuzzy Inference 被引量:2
10
作者 Wenjia Xiang Xiaoyu Li +4 位作者 Zirui He Chenjing Su Wangchi Cheng Chao Lu Shan Yang 《Intelligent Automation & Soft Computing》 SCIE 2023年第3期3627-3639,共13页
Estimating the intention of space objects plays an important role in air-craft design,aviation safety,military and otherfields,and is an important refer-ence basis for air situation analysis and command decision-making... Estimating the intention of space objects plays an important role in air-craft design,aviation safety,military and otherfields,and is an important refer-ence basis for air situation analysis and command decision-making.This paper studies an intention estimation method based on fuzzy theory,combining prob-ability to calculate the intention between two objects.This method takes a space object as the origin of coordinates,observes the target’s distance,speed,relative heading angle,altitude difference,steering trend and etc.,then introduces the spe-cific calculation methods of these parameters.Through calculation,values are input into the fuzzy inference model,andfinally the action intention of the target is obtained through the fuzzy rule table and historical weighted probability.Ver-ified by simulation experiment,the target intention inferred by this method is roughly the same as the actual behavior of the target,which proves that the meth-od for identifying the target intention is effective. 展开更多
关键词 Intension estimation motion parameters calculation fuzzy inference fuzzy rule table historical weighted probability
下载PDF
GRADIENT ESTIMATES AND ENTROPY FORMULAE FOR WEIGHTED p-HEAT EQUATIONS ON SMOOTH METRIC MEASURE SPACES 被引量:4
11
作者 王宇钊 杨杰 陈文艺 《Acta Mathematica Scientia》 SCIE CSCD 2013年第4期963-974,共12页
Let (M,g, e^-fdv) be a smooth metric measure space. In this paper, we con- sider two nonlinear weighted p-heat equations. Firstly, we derive a Li-Yau type gradient estimates for the positive solutions to the followi... Let (M,g, e^-fdv) be a smooth metric measure space. In this paper, we con- sider two nonlinear weighted p-heat equations. Firstly, we derive a Li-Yau type gradient estimates for the positive solutions to the following nonlinear weighted p-heat equationand f is a smooth function on M under the assumptionthat the m-dimensional nonnegative Bakry-Emery Ricci curvature. Secondly, we show an entropy monotonicity formula with nonnegative m-dimensional Bakry-Emery Ricci curva- ture which is a generalization to the results of Kotschwar and Ni [9], Li [7]. 展开更多
关键词 gradient estimates weighted p-heat equation entropy monotonicity formula m-Bakry-t^mery Ricci curvature
下载PDF
A sharp gradient estimate for the weighted p-Laplacian 被引量:2
12
作者 WANG Lin-feng ZHU Yue-ping 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2012年第4期462-474,共13页
Let M be an n-dimensional complete noncompact Riemannian manifold with sectional curvature bounded from below, dμ = e^h(x) dV(x) the weighted measure and △μ,p the weighted p-Laplacian. In this paper we consider... Let M be an n-dimensional complete noncompact Riemannian manifold with sectional curvature bounded from below, dμ = e^h(x) dV(x) the weighted measure and △μ,p the weighted p-Laplacian. In this paper we consider the non-linear elliptic equation △μ,pu=-λμ,p|u|^p-2ufor p ∈ (1, 2). We derive a sharp gradient estimate for positive smooth solutions of this equation. As applications, we get a Harnack inequality and a Liouville type theorem.. 展开更多
关键词 weighted p-Laplacian gradient estimate Harnack inequality Liouville theorem.
下载PDF
Ultrasound estimation of fetal weight in twins by artificial neural network 被引量:2
13
作者 Hanieh Mohammadi Meshkat Nemati +3 位作者 Zohreh Allahmoradi Hoda Forghani Raissi Somayeh Saraf Esmaili Ali Sheikhani 《Journal of Biomedical Science and Engineering》 2011年第1期46-50,共5页
This study was undertaken to determine the accuracy of using Ultrasound (US) estimation of twin fetuses by use of Artificial Neural Network. At First, as the training group, we performed US examinations on 186 healthy... This study was undertaken to determine the accuracy of using Ultrasound (US) estimation of twin fetuses by use of Artificial Neural Network. At First, as the training group, we performed US examinations on 186 healthy singleton fetuses within 3 days of delivery. Three input variables were used to construct the ANN model: abdominal circumference (AC), ab-dominal diameter (AD), biparietal diameter (BPD). Then, a total of 121 twin fetuses were assessed sub-sequently as the validation group. In validation group, the mean absolute error and the mean absolute per-cent error between estimated fetal weight and actual fetal weight was 261.77 g and 7.81%, respectively. Results show that, twin estimation of birth weight by ultrasound correlates fairly well with the actual weights of twin fetuses. 展开更多
关键词 ULTRASOUND FETAL weight estimation TWIN Artificial Neural Network
下载PDF
The RAMA Ped Card: Does it work for actual weight estimation in child patients at the emergency department 被引量:2
14
作者 Thavinee Trainarongsakul Pitsucha Sanguanwit +2 位作者 Supawan Rojcharoenchai Kittisak Sawanyawisuth Yuwares Sittichanbuncha 《World Journal of Emergency Medicine》 CAS 2017年第2期126-130,共5页
BACKGROUND: In emergency conditions, the actual weight of infants and young children are essential for treatments. The RAMATHIBODI Pediatric Emergency Drug Card or RAMA Ped Card has also been developed to estimate act... BACKGROUND: In emergency conditions, the actual weight of infants and young children are essential for treatments. The RAMATHIBODI Pediatric Emergency Drug Card or RAMA Ped Card has also been developed to estimate actual weight of the subjects. This study aimed to validate the RAMA Ped Card in correctly identifying the actual weight of infants and young adults.METHODS: This study was a prospective study. We enrolled all consecutive patients under 15 years of age who visited the emergency department(ED). All eligible patients' actual weight and height were measured at the screening point of the ED. The weight of each patient was also measured using the unlabeled RAMA Ped Card. The Cohen's kappa values and agreement percentages were calculated.RESULTS: During the study period, there were 345 eligible patients. The RAMA Ped Card had a 61.16% agreement with the actual weight with a kappa of 0.54(P<0.01), while the agreement with the actual height had a kappa of 0.90 and 91.59% agreement. Sub-group analysis found kappa scores with good range in two categories: in cases of accidents and in the infant group(kappa of 0.68 and 0.65, respectively).CONCLUSION: The RAMA Ped Card had a fair correlation with the actual weight in child patients presenting at the ED. Weight estimation in infant patients and children who presented with accidents were more accurate. 展开更多
关键词 CHILD weight estimation CARD KAPPA
下载PDF
Hamilton-Souplet-Zhang's gradient estimates for two weighted nonlinear parabolic equations 被引量:1
15
作者 MA Bing-qing HUANG Guang-yue 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2017年第3期353-364,共12页
In this paper, we consider gradient estimates for positive solutions to the following weighted nonlinear parabolic equations on a complete smooth metric measure space with only Bakry-Émery Ricci tensor bounded be... In this paper, we consider gradient estimates for positive solutions to the following weighted nonlinear parabolic equations on a complete smooth metric measure space with only Bakry-Émery Ricci tensor bounded below: One is $${u_t} = {\Delta _f}u + au\log u + bu$$ with a, b two real constants, and another is $${u_t} = {\Delta _f}u + \lambda {u^\alpha }$$ with λ, α two real constants. We obtain local Hamilton-Souplet-Zhang type gradient estimates for the above two nonlinear parabolic equations. In particular, our estimates do not depend on any assumption on f. 展开更多
关键词 Hamilton’s gradient estimate Souplet-Zhang’s gradient estimate weighted nonlinear parabolic equation Bakry-Émery Ricci tensor
下载PDF
Weighted Maximum Likelihood Technique for Logistic Regression
16
作者 Idriss Abdelmajid Idriss Weihu Cheng Yemane Hailu Fissuh 《Open Journal of Statistics》 2023年第6期803-821,共19页
In this paper, a weighted maximum likelihood technique (WMLT) for the logistic regression model is presented. This method depended on a weight function that is continuously adaptable using Mahalanobis distances for pr... In this paper, a weighted maximum likelihood technique (WMLT) for the logistic regression model is presented. This method depended on a weight function that is continuously adaptable using Mahalanobis distances for predictor variables. Under the model, the asymptotic consistency of the suggested estimator is demonstrated and properties of finite-sample are also investigated via simulation. In simulation studies and real data sets, it is observed that the newly proposed technique demonstrated the greatest performance among all estimators compared. 展开更多
关键词 Logistic Regression Clean Model Robust estimation Contaminated Model weighted Maximum Likelihood Technique
下载PDF
Estimation of Weight and Lipid Composition in Preimplantation Embryos from Jersey and Beef Breeds of Cattle 被引量:1
17
作者 Julie D. Weathers Samuel D. Prien 《Open Journal of Veterinary Medicine》 2014年第11期261-266,共6页
Cryopreservation is the main functional means for storage of excess embryos produced from artificial reproductive technologies;the process assumes embryos chemical nature is highly conserved across embryos of the same... Cryopreservation is the main functional means for storage of excess embryos produced from artificial reproductive technologies;the process assumes embryos chemical nature is highly conserved across embryos of the same species. However, in practice there appears to be a high degree of variability in embryo tolerance to cryopreservation, suggesting potential differences in embryo chemistry. The objective of the current study was to develop reproducible means of estimating relative embryos weight and associating those weights to lipid content. Relative embryo weights of frozen/thawed in-vivo Jersey and Crossbred beef breed embryos were determined using a modified specific gravity chamber. Embryo weights were then correlated with lipid content. Results suggest that beef cattle embryos are 20% - 27% heavier than Jersey embryos 展开更多
关键词 estimated weight Embryo CRYOPRESERVATION CATTLE
下载PDF
Unbiased Estimation Formula of Unit Weight Standard Deviation in Regularization Solution 被引量:1
18
作者 SHENYunzhong LIUDajie 《Geo-Spatial Information Science》 2004年第3期210-213,共4页
Regularization method is an effective method for solving ill\|posed equation. In this paper the unbiased estimation formula of unit weight standard deviation in the regularization solution is derived and the formula i... Regularization method is an effective method for solving ill\|posed equation. In this paper the unbiased estimation formula of unit weight standard deviation in the regularization solution is derived and the formula is verified with numerical case of 1 000 sample data by use of the typical ill\|posed equation, i.e. the Fredholm integration equation of the first kind. 展开更多
关键词 regularization solution unit weight standard deviation unbiased estimation
下载PDF
WEIGHTED WEAK TYPE ESTIMATES INVOLVING SPACES GENERATED BY BLOCKS 被引量:1
19
作者 Lu Shanzhen Guido Weiss Beijing Normal University Washington University inst. Louis 《Analysis in Theory and Applications》 1994年第1期58-64,共7页
The problem studied in this paper is how to establish weighted estimates of weak type near L^1 for those operators that are not of weak type(1,1).
关键词 show Math weighted WEAK TYPE estimATES INVOLVING SPACES GENERATED BY BLOCKS
下载PDF
The “PAWPER-on-a-page”: Increasing global access to a low-cost weight estimation system
20
作者 Mike Wells Lara Nicole Goldstein 《World Journal of Emergency Medicine》 SCIE CAS CSCD 2019年第2期101-108,共8页
BACKGROUND: The PAWPER tape is one of the most accurate weight estimation systems available today, but international access to the tape is limited because it has no commercial distribution. For this reason, the "... BACKGROUND: The PAWPER tape is one of the most accurate weight estimation systems available today, but international access to the tape is limited because it has no commercial distribution. For this reason, the "PAWPER-on-a-page" concept was devised: downloadable image fi les that allow users to print and assemble their own tapes. However, the feasibility of this method is dependent on users being able to produce accurate tapes. This study was devised to determine whether untrained participants could print and assemble the "PAWPER-on-a-page" easily and accurately.METHODS: Doctor and nurse volunteers downloaded the "PAWPER-on-a-page" and "PAWPER XL-on-a-page" image files and printed copies on a home-printer and also at a commercial printer. One copy of each tape was then assembled according to instructions from an online video. The accuracy of printing and assembly, the time taken for assembly and the cost were then evaluated.RESULTS: There were 32 participants. The median time for assembly was 8 minutes 19 seconds and 7 minutes 31 seconds for the "PAWPER-on-a-page" and "PAWPER XL-on-a-page" respectively, with a median cost of USD 0.09 and USD 1.00 respectively. For the assembled tapes, 71.9% of the "PAWPER-on-a-page" tapes and 65.6% of the "PAWPER XL-on-a-page" achieved the required accuracy of 0.2%. Printing errors, related to scaling, were common, but easily detectable.CONCLUSION: The "PAWPER-on-a-page" system can be easily, quickly, affordably and accurately printed and assembled by end users. Stringent double checking of the printed and fully assembled tapes is essential to ensure accuracy. 展开更多
关键词 PAWPER TAPE weight estimation PAEDIATRIC EMERGENCY CARE
下载PDF
上一页 1 2 107 下一页 到第
使用帮助 返回顶部