期刊文献+
共找到2,200篇文章
< 1 2 110 >
每页显示 20 50 100
Association between operative position and postoperative nausea and vomiting in patients undergoing laparoscopic sleeve gastrectomy
1
作者 Zhao-Peng Li Yan-Cheng Song +3 位作者 Ya-Li Li Dong Guo Dong Chen Yu Li 《World Journal of Gastrointestinal Surgery》 SCIE 2024年第7期2088-2095,共8页
BACKGROUND Bariatric surgery is one of the most effective ways to treat morbid obesity,and postoperative nausea and vomiting(PONV)is one of the common complications after bariatric surgery.At present,the mechanism of ... BACKGROUND Bariatric surgery is one of the most effective ways to treat morbid obesity,and postoperative nausea and vomiting(PONV)is one of the common complications after bariatric surgery.At present,the mechanism of the high incidence of PONV after weight-loss surgery has not been clearly explained,and this study aims to investigate the effect of surgical position on PONV in patients undergoing bariatric surgery.AIM To explore the effect of the operative position during bariatric surgery on PONV.METHODS Data from obese patients,who underwent laparoscopic sleeve gastrectomy(LSG)in the authors’hospital between June 2020 and February 2022 were divided into 2 groups and retrospectively analyzed.Multivariable logistic regression analysis and the t-test were used to study the influence of operative position on PONV.RESULTS There were 15 cases of PONV in the supine split-leg group(incidence rate,50%)and 11 in the supine group(incidence rate,36.7%)(P=0.297).The mean operative duration in the supine split-leg group was 168.23±46.24 minutes and 140.60±32.256 minutes in the supine group(P<0.05).Multivariate analysis revealed that operative position was not an independent risk factor for PONV(odds ratio=1.192,95%confidence interval:0.376-3.778,P=0.766).CONCLUSION Operative position during LSG may affect PONV;however,the difference in the incidence of PONV was not statistically significant.Operative position should be carefully considered for obese patients before surgery. 展开更多
关键词 Postoperative nausea and vomiting Bariatric surgery Laparoscopic sleeve gastrectomy operative positions OBESITY
下载PDF
Feynman Path Integral Using Operator Integration in Banach Space
2
作者 Reza R. Ahangar Erbil Cetin Serife Muge Ege 《Journal of Applied Mathematics and Physics》 2024年第2期432-444,共13页
Feynman-Path Integral in Banach Space: In 1940, R.P. Feynman attempted to find a mathematical representation to express quantum dynamics of the general form for a double-slit experiment. His intuition on several slits... Feynman-Path Integral in Banach Space: In 1940, R.P. Feynman attempted to find a mathematical representation to express quantum dynamics of the general form for a double-slit experiment. His intuition on several slits with several walls in terms of Lagrangian instead of Hamiltonian resulted in a magnificent work. It was known as Feynman Path Integrals in quantum physics, and a large part of the scientific community still considers them a heuristic tool that lacks a sound mathematical definition. This paper aims to refute this prejudice, by providing an extensive and self-contained description of the mathematical theory of Feynman Path Integration, from the earlier attempts to the latest developments, as well as its applications to quantum mechanics. About a hundred years after the beginning of modern physics, it was realized that light could in fact show behavioral characteristics of both waves and particles. In 1927, Davisson and Germer demonstrated that electrons show the same dual behavior, which was later extended to atoms and molecules. We shall follow the method of integration with some modifications to construct a generalized Lebesgue-Bochner-Stieltjes (LBS) integral of the form , where u is a bilinear operator acting in the product of Banach spaces, f is a Bochner summable function, and μ is a vector-valued measure. We will demonstrate that the Feynman Path Integral is consistent and can be justified mathematically with LBS integration approach. 展开更多
关键词 Feynman Path Integral Lebesgue-Bochner-Stieltjes Integral operator Integral Particle-Wave Function operator Integration position and Momentum operators
下载PDF
Positioning-control Based on Trapezoidal Velocity Curve for High-precision Basis Weight Control Valve 被引量:3
3
作者 Bo Wang Wei Tang +1 位作者 JiXian Dong Feng Wang 《Paper And Biomaterials》 2017年第2期42-50,共9页
Traditionally, basis weight control valve is driven by a constant frequency pulse signal. Therefore, it is difficult for the valve to match the control precision of basis weight. Dynamic simulation research using Matl... Traditionally, basis weight control valve is driven by a constant frequency pulse signal. Therefore, it is difficult for the valve to match the control precision of basis weight. Dynamic simulation research using Matlab/Simulink indicates that there is much more overshoot and fluctuating during the valve-positioning process. In order to improve the valve-positioning precision, the control method of trapezoidal velocity curve was studied. The simulation result showed that the positioning steady-state error was less than 0.0056%, whereas the peak error was less than 0.016% by using trapezoidal velocity curve at 10 positioning steps. A valve-positioning precision experimental device for the stepper motor of basis weight control valve was developed. The experiment results showed that the error ratio of 1/10000 positioning steps was 4% by using trapezoidal velocity curve. Furthermore, the error ratio of 10/10000 positioning steps was 0.5%. It proved that the valve-positioning precision of trapezoidal velocity curve was much higher than that of the constant frequency pulse signal control strategy. The new control method of trapezoidal velocity curve can satisfy the precision requirement of 10000 steps. 展开更多
关键词 high-precision basis weight control valve precision positioning control trapezoidal velocity curve Matlab/Simulink simulation
下载PDF
Operator Matrix Forms of Positive Operators 被引量:4
4
作者 杜鸿科 《Chinese Quarterly Journal of Mathematics》 CSCD 1992年第4期9-12,共4页
If a 3-tuple (A:H_1→H_1,B:H_2→H_1,C:H_2→H_2) of operators on Hilbert spaces is given,we proved that the operator A:= on H=H_1⊕H_2 is≥0 if and only if A≥0,R(B) R(A1/2)and C≥B~* A^+ B, where A^+ is the generalize... If a 3-tuple (A:H_1→H_1,B:H_2→H_1,C:H_2→H_2) of operators on Hilbert spaces is given,we proved that the operator A:= on H=H_1⊕H_2 is≥0 if and only if A≥0,R(B) R(A1/2)and C≥B~* A^+ B, where A^+ is the generalized inverse of A. In general,A^+ is a closed operator,but since R(B) R(A1/2),B~* A^+ B is bounded yet. 展开更多
关键词 positive operator range of operator
下载PDF
THE RELATION BETWEEN SIGN-CHANGING SOLUTION AND POSITIVE-NEGATIVE SOLUTIONS FOR NONLINEAR OPERATOR EQUATIONS AND ITS APPLICATIONS 被引量:1
5
作者 张克梅 孙经先 《Acta Mathematica Scientia》 SCIE CSCD 2004年第3期463-468,共6页
By fixed point index theory and a result obtained by Amann, existence of the solution for a class of nonlinear operator equations x = Ax is discussed. Under suitable conditions, a couple of positive and negative solut... By fixed point index theory and a result obtained by Amann, existence of the solution for a class of nonlinear operator equations x = Ax is discussed. Under suitable conditions, a couple of positive and negative solutions are obtained. Finally, the abstract result is applied to nonlinear Sturm-Liouville boundary value problem, and at least four distinct solutions are obtained. 展开更多
关键词 CONE fixed point index theory uniformly positive operator.
下载PDF
Implementation of positive-operator-value measurements for single spin qubit via Heisenberg model 被引量:2
6
作者 程留永 邵晓强 +1 位作者 张寿 Yeon Kyu-Hwangc 《Chinese Physics B》 SCIE EI CAS CSCD 2010年第9期140-144,共5页
This paper shows that a proposal for implementing all possible two-operator positive-operator-value measurements of single spin qubit can be obtained via introducing another spin qubit as ancilla. The realization proc... This paper shows that a proposal for implementing all possible two-operator positive-operator-value measurements of single spin qubit can be obtained via introducing another spin qubit as ancilla. The realization process is accomplished from the free evolution of the Heisenberg XX model by considering nearest-neighbour spin interaction. A controlled- NOT gate, which is a significant operator for this scheme is also constructed and the generalisation to multiple-operator is considered finally. 展开更多
关键词 positive-operator-value measurements single spin qubit Heisenberg model
下载PDF
MEAN CONVERGENCE OF SOME POSITIVE OPERATORS
7
作者 史应光 《Acta Mathematica Scientia》 SCIE CSCD 1995年第2期136-143,共8页
L'convergence with 0<p<infinity of the positive operators F.(da,f) and G.(da,f), introduced by Nevai P. [3], and Qn,8(da,f), introduced by Hermann T. and Vertesi P. [1] to f is an element of C[-1,1] is prove... L'convergence with 0<p<infinity of the positive operators F.(da,f) and G.(da,f), introduced by Nevai P. [3], and Qn,8(da,f), introduced by Hermann T. and Vertesi P. [1] to f is an element of C[-1,1] is proved to hold for very general measures. 展开更多
关键词 positIVE operatorS MEAN CONVERGENCE ORTHOGONAL POLYNOMIALS
下载PDF
The Spectrum of Positive Operators on Hilbert Lattices
8
作者 DENG Chun-yuan DU Hong-ke 《Chinese Quarterly Journal of Mathematics》 CSCD 北大核心 2007年第1期52-56,共5页
Some spectral characterizations of positive operators on Hilbert lattices are presented. The application of these results can yield some equivalent relations of an irreducible positive operator. Some related results f... Some spectral characterizations of positive operators on Hilbert lattices are presented. The application of these results can yield some equivalent relations of an irreducible positive operator. Some related results for positive operators on Hilbert lattice are also obtained. 展开更多
关键词 Hilbert lattice positive operator IDEAL IRREDUCIBLE operator
下载PDF
Complete Positivity of Elementary Operators on C^*—algebras
9
作者 李建奎 《Chinese Quarterly Journal of Mathematics》 CSCD 1997年第4期51-54, ,共4页
Let E(x) = be an elementary operator on a C-algebra A. We prove that if A is prime with soc(A) = 0, or there is a family of irreducible representation of A such that is faithful and (A) does not contain compact operat... Let E(x) = be an elementary operator on a C-algebra A. We prove that if A is prime with soc(A) = 0, or there is a family of irreducible representation of A such that is faithful and (A) does not contain compact operator,or A has a faithful repre sentation π such that π(A)″with no central portions of type In for n>1 then E is positive if and only if E is completely positive. 展开更多
关键词 elementary operator complete positivity
下载PDF
A New Class of Generalized Landau Linear Positive Operator Sequence and Its Properties of Approximation
10
作者 陈湛本 石济民 《Chinese Quarterly Journal of Mathematics》 CSCD 1998年第1期29-43, ,共15页
In this paper two sequences of generalized Landau linear positive operators are introduced. They can be applied in approximating continuous functions with arbitrary growth order, defined on a finite interval or the wh... In this paper two sequences of generalized Landau linear positive operators are introduced. They can be applied in approximating continuous functions with arbitrary growth order, defined on a finite interval or the whole real axis. The properties of approximation are studied and their asymptotic formulae are presented. These results show that their degrees of approximation are the best among existing operator sequences of Landau type, for example, their degrees of approximation for C 2[0, 1] are O(1/n 2) but corresponding degree of ordinary Landau operators are only O(1/n). 展开更多
关键词 generalized Landau linear positive operators degree of approximation asymptotic formula
下载PDF
Application Of Jessen's Type Inequality For Positive C0-Semigroup Of Operators
11
作者 Gul I Hina Aslam Matloob Anwar 《Journal of Statistical Science and Application》 2015年第4期122-129,共8页
Recently in [4], the Jessen's type inequality for normalized positive C0-semigroups is obtained. In this note, we present few results of this inequality, yielding Holder's Type and Minkowski's type inequalities for... Recently in [4], the Jessen's type inequality for normalized positive C0-semigroups is obtained. In this note, we present few results of this inequality, yielding Holder's Type and Minkowski's type inequalities for corresponding semigroup. Moreover, a Dresher's type inequality for two-parameter family of means, is also proved. 展开更多
关键词 Mean inequalities positive semigroup of operators HOlder's Type Inequality Minkowski's TypeInequality Dresher's Type Inequality.
下载PDF
A new approach to obtaining positive-definite Wigner operator for two entangled particles with different masses
12
作者 范洪义 徐学翔 +4 位作者 袁洪春 王帅 王震 许朋 姜年权 《Chinese Physics B》 SCIE EI CAS CSCD 2011年第7期47-51,共5页
Based on our previously proposed Wigner operator in entangled form, we introduce the generalized Wigner operator for two entangled particles with different masses, which is expected to be positive-definite. This appro... Based on our previously proposed Wigner operator in entangled form, we introduce the generalized Wigner operator for two entangled particles with different masses, which is expected to be positive-definite. This approach is able to convert the generalized Wigner operator into a pure state so that the positivity can be ensured. The technique of integration within an ordered product of operators is used in the discussion. 展开更多
关键词 positive-definite Wigner operator entangled form marginal distribution
下载PDF
Evaluation index system for positive operation of water conservancy projects 被引量:3
13
作者 Qing-yuan ZHU Guo-hua FANG 《Water Science and Engineering》 EI CAS 2009年第4期110-117,共8页
The conditions for the positive operation of water conservancy projects are described in this paper. A scientific and effective evaluation index system was established based on frequency analysis, theoretical analysis... The conditions for the positive operation of water conservancy projects are described in this paper. A scientific and effective evaluation index system was established based on frequency analysis, theoretical analysis, and expert consultation. This evaluation index system can be divided into six first-level indices: the degree to which facilities are intact and functionality standards are reached, the status of operation and management funds, the rationality and degree of advancement of the management team structure, the adaptability and rationality of the water conservancy project management system, the degree of automatization and informationization of the management techniques, and the conduciveness of the exterior environment. The weights for evaluation indices were obtained through the analytic hierarchy process method with consideration of the difference between public welfare and profit-oriented water conservancy projects. This study provides a scientific method for evaluating the positive operation of water conservancy projects. 展开更多
关键词 water conservancy project positive operation evaluation index system analytic hierarchy process WEIGHT
下载PDF
Virtual Reality Simulation of Fuzzy-logic Control during Underwater Dynamic Positioning 被引量:4
14
作者 Midhin Das Thekkedan Cheng Siong Chin Wai Lok Woo 《Journal of Marine Science and Application》 CSCD 2015年第1期14-24,共11页
In this paper, graphical-user-interface (GUI) software for simulation and fuzzy-logic control of a remotely operated vehicle (ROV) using MATLABTM GUI Designing Environment is proposed. The proposed ROV's GUI plat... In this paper, graphical-user-interface (GUI) software for simulation and fuzzy-logic control of a remotely operated vehicle (ROV) using MATLABTM GUI Designing Environment is proposed. The proposed ROV's GUI platform allows the controller such as fuzzy-logic control systems design to be compared with other controllers such as proportional-integral-derivative (PID) and sliding-mode controller (SMC) systematically and interactively. External disturbance such as sea current can he added to improve the modelling in actual underwater environment. The simulated results showed the position responses of the fuzzy-logic control exhibit reasonable performance under the sea current disturbance. 展开更多
关键词 graphical-user-interface (GUI) fuzzy-logic control remotely operated vehicle (ROV) proportional-integral-derivative (PID) sliding-mode controller (SMC) underwater dynamic positioning
下载PDF
ASYMPTOTIC APPROXIMATION OF FUNCTIONS AND THEIR DERIVATIVES BY GENERALIZED BASKAKOV-SZAZS-DURRMEYER OPERATORS 被引量:1
15
作者 Ulrich Abel Vijay Gupta Mircea Ivan 《Analysis in Theory and Applications》 2005年第1期15-26,共12页
We present the complete asymptotic expansion for a generalization of the Baskakov-Szasz-Durrmeyer operators and their derivatives.
关键词 approximation by positive operators rate of convergence degree of approximation asymptotic expansion Stirling numbers
下载PDF
BP-LMS-based BDS-3 power system positioning method 被引量:1
16
作者 Ruifeng Zhao Jiangang Lu +2 位作者 Wenxin Guo Wenjie Zheng Shiming Li 《Global Energy Interconnection》 EI CAS CSCD 2022年第6期666-674,共9页
The BeiDou-3 navigation satellite system(BDS-3)provides a full-domain high-precision positioning service for the power system to ensure safe and stable operation.However,BDS-3 power system positioning faces certain ch... The BeiDou-3 navigation satellite system(BDS-3)provides a full-domain high-precision positioning service for the power system to ensure safe and stable operation.However,BDS-3 power system positioning faces certain challenges,such as complex electromagnetic interference and incomplete error elimination.Herein,a back propagation neural network-improved least mean square(BP-LMS)adaptive filtering method is proposed for the BDS-3 full-domain and high-precision power system positioning,which utilizes the loss function to update the weight of the BP hidden layer,computes the pseudo compensation range,and eliminates the impact of electromagnetic interference to enhance the accuracy of power system positioning.Simulation results confirm the superior performance of BP-LMS in positioning accuracy and error elimination.Compared with LMS and normalized least mean square(NLMS),the filtering error of the proposed BP-LMS adaptive filtering method is decreased by 57.14%and 51.38%,respectively. 展开更多
关键词 BDS-3 BP-LMS Error elimination Full-domain and high-precision positioning Power system
下载PDF
Application and Practice of High-Precision Solar Resource Monitoring Technology in Photovoltaic Power Plant Area 被引量:1
17
作者 Rong Zhou Xiaolei Zhang 《Journal of Power and Energy Engineering》 2019年第11期55-63,共9页
Solar resource monitoring and evaluation is the foundation of informatization of photovoltaic power station. In 2016, China began to bring in high-precision solar resource monitoring technology which provides reliable... Solar resource monitoring and evaluation is the foundation of informatization of photovoltaic power station. In 2016, China began to bring in high-precision solar resource monitoring technology which provides reliable basic data for the photovoltaic informatization development. This paper systematically sorts out design basis, monitoring elements and system architecture of high-precision monitoring station, and analyzes operation effect of high-precision solar resource monitoring station from performance of solar radiation meter and prediction results of luminous power, which provide important data support for analysis of power generation efficiency of photovoltaic module, prediction of power generation of power station, evaluation of operation effect of power station, etc. 展开更多
关键词 high-precision SOLAR RESOURCE MONITORING STATION operation Effect
下载PDF
AN ORDER PRESERVING INEQUALITY FOR THREE OPERATORS VIA FURUTA INEQUALITY
18
作者 杨长森 《Acta Mathematica Scientia》 SCIE CSCD 2008年第4期998-1002,共5页
Furuta showed that if A≥B≥0,then for each r≥0,f(p)=(A^r/2 B^p A^r/2)^t+r/p+r is decreasing for p≥t≥0.Using this result,the following inequality(C^r/2(AB^2A)^δC^ r/2)^ p-1+r/4δ+r ≤C^p-1+r is obtain... Furuta showed that if A≥B≥0,then for each r≥0,f(p)=(A^r/2 B^p A^r/2)^t+r/p+r is decreasing for p≥t≥0.Using this result,the following inequality(C^r/2(AB^2A)^δC^ r/2)^ p-1+r/4δ+r ≤C^p-1+r is obtained for 0〈p ≤1,r≥1,1/4≤δ≤1 and three positive operators A, B, C satisfy(A^1/2BA^1/2)^p/2≤A^p,(B^1/2AB^1/2)^p/2≥B^p,(C^1/2AC^1/2)^p/2≤C^p,(A^1/2CA^1/2)^p/2≥A^p. 展开更多
关键词 positive operator Furuta inequality operator inequality
下载PDF
NEW SUBCLASS OF ANALYTIC FUNCTIONS IN CONICAL DOMAIN ASSOCIATED WITH A LINEAR OPERATOR
19
作者 Muhammed ARIF Shahid MAHMOOD +1 位作者 Janusz SOKOL Jacek DZIOK 《Acta Mathematica Scientia》 SCIE CSCD 2016年第3期704-716,共13页
The main object of the present paper is to investigate a number of useful properties such as inclusion relations, distortion bounds, coefficient estimates, subordination results, the Fekete-Szego problem and some othe... The main object of the present paper is to investigate a number of useful properties such as inclusion relations, distortion bounds, coefficient estimates, subordination results, the Fekete-Szego problem and some other for a new subclass of analytic functions, which are defined here by means of linear operator. Relevant connections of the results presented here with those obtained in earlier works are also pointed out. 展开更多
关键词 analytie functions SUBORDINATION functions with positive real part linear operators conic domains
下载PDF
On Approximation Properties of Modified Sázas-Mirakyan Operators via Jain Operators
20
作者 Prashantkumar Patel Vishnu Narayan Mishra 《Analysis in Theory and Applications》 CSCD 2016年第3期232-241,共10页
In the present manuscript, we propose the modification of Jain operators which the generalization of Szasz-Mirakyan operators. These new class operators are linear positive operators of discrete type depending on a re... In the present manuscript, we propose the modification of Jain operators which the generalization of Szasz-Mirakyan operators. These new class operators are linear positive operators of discrete type depending on a real parameters. We give theorem of degree of approximation and the Voronovskaya asymptotic formula. 展开更多
关键词 positive linear operators Jain operators Szasz-Mirakyan operator.
下载PDF
上一页 1 2 110 下一页 到第
使用帮助 返回顶部