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不同光滑变量的变系数模型的系数函数的有效估计
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作者 冯井艳 张日权 卢准炜 《太原科技大学学报》 2008年第6期426-428,共3页
探讨不同自变量的变系数模型的系数函数的估计及其渐近性。使用局部线性方法和平均方法给出系数函数的平均估计,对平均估计使用回切法给出系数函数的有效估计,给出它们的渐近正态性,模拟例子说明这个估计的有效性。
关键词 变系数模型 不同自变量 局部线性方 平均方 回切法 有效估计 渐近正态性
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Choice of approach for hepatectomy for hepatocellular carcinoma located in the caudate lobe:Isolated or combined lobectomy? 被引量:13
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作者 Peng Liu Bao-An Qiu Gang Bai Hong-Wei Bai Nian-Xin Xia Ying-Xiang Yang Jian-Yong Zhu Yang An Bing Hu 《World Journal of Gastroenterology》 SCIE CAS CSCD 2012年第29期3904-3909,共6页
AIM:To investigate the significance of the surgical approaches in the prognosis of hepatocellular carcinoma(HCC) located in the caudate lobe with a multivariate regression analysis using a Cox proportional hazard mode... AIM:To investigate the significance of the surgical approaches in the prognosis of hepatocellular carcinoma(HCC) located in the caudate lobe with a multivariate regression analysis using a Cox proportional hazard model.METHODS:Thirty-six patients with HCC underwent caudate lobectomy at a single tertiary referral center between January 1995 and June 2010.In this series,left-sided,right-sided and bilateral approaches were used.The outcomes of patients who underwent isolated caudate lobectomy or caudate lobectomy combined with an additional partial hepatectomy were compared.The survival curves of the isolated and combined resection groups were generated by the Kaplan-Meier method and compared by a log-rank test.RESULTS:Sixteen(44.4%) of 36 patients underwent isolated total or partial caudate lobectomy whereas 20(55.6%) received a total or partial caudate lobectomy combined with an additional partial hepatectomy.The median diameter of the tumor was 6.7 cm(range,2.1-15.8 cm).Patients who underwent an isolated caudate lobectomy had significantly longer operative time(240 min vs 170 min),longer length of hospital stay(18 d vs 13 d) and more blood loss(780 mL vs 270 mL) than patients who underwent a combined caudate lobectomy(P < 0.05).There were no perioperative deaths in both groups of patients.The complication rate was higher in the patients who underwent an isolated caudate lobectomy than in those who underwent combined caudate lobectomy(31.3% vs 10.0%,P < 0.05).The 1-,3-and 5-year disease-free survival rates for the isolated caudate lobectomy and the combined caudate lobectomy groups were 54.5%,6.5% and 0% and 85.8%,37.6% and 0%,respectively(P < 0.05).The corresponding overall survival rates were 73.8%,18.5% and 0% and 93.1%,43.6% and 6.7%(P < 0.05).CONCLUSION:The caudate lobectomy combined with an additional partial hepatectomy is preferred because this approach is technically less demanding and offers an adequate surgical margin. 展开更多
关键词 Hepatocellular carcinoma Hepatectomy Caudate lobectomy Caudate lobe Combined resection
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Investigation of Cutting Force by End Milling Operation
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《Journal of Mechanics Engineering and Automation》 2014年第1期91-95,共5页
In this work, the cutting forces by end milling operation are analyzed. Therefore, the main parameters of cutting force as cutting speed, feed rate and depth of cut also are investigated in our case. The cutting force... In this work, the cutting forces by end milling operation are analyzed. Therefore, the main parameters of cutting force as cutting speed, feed rate and depth of cut also are investigated in our case. The cutting force is modelled and analyzed into mathematical Wolfram simulations in order to compare the results and in the same time achieve the best solutions. Theoretical results are carried out by using the regression method that required fulfilling the critter by Fisher. The number of experiment, measurements and results of cutting force are presented in 2D as well as 3D. In order to verify the accuracy of the 2D diagram, the results for our case is used both two way such as experimental and theoretical method as well as results are compared. In other hands, these results indicate directly that the optimized parameters are capable of machining the workpiece. The obtained measurement results are compared with theoretical methods in Wolfram software. 展开更多
关键词 Cutting force CNC (computer numerical control) machine tools end milling.
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不同自变量的变系数模型的估计
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作者 冯井艳 张日权 张志强 《系统科学与数学》 CSCD 北大核心 2010年第2期225-235,共11页
讨论具有不同自变量的变系数模型的函数系数的估计及其大样本性质。使用局部线性方法和积分方法,得到函数系数的积分估计;由于该估计有较大的方差,进一步使用回切法改进这一估计,获得了函数系数的改进估计;同时,研究了改进估计的渐近正... 讨论具有不同自变量的变系数模型的函数系数的估计及其大样本性质。使用局部线性方法和积分方法,得到函数系数的积分估计;由于该估计有较大的方差,进一步使用回切法改进这一估计,获得了函数系数的改进估计;同时,研究了改进估计的渐近正态性。最后,用模拟例子说明提出的估计方法是有效的。 展开更多
关键词 变系数模型 局部线性方 积分方 回切法 渐近正态性
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