首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 546 毫秒
1.
In this paper,the T_φ-convex functions were introduced as a generalizations of convex functions.Then the character- istics of the T_φ-convex functions were discussed.Furthermore,some new inequalities for the T_φ-convex functions were derived.  相似文献   

2.
无约束全局最优化中的无参数填充函数   总被引:1,自引:0,他引:1  
The filled function method is an approach for finding a global minimum of multi-dimensional functions.With more and more relevant research,it becomes a promising way used in unconstrained global optimization.Some filled functions with one or two parameters have already been suggested.However,there is no certain criterion to choose a parameter appropriately.In this paper,a parameter-free filled function was proposed.The definition of the original filled function and assumptions of the objective function given by Ge were improved according to the presented parameter-free filled function.The algorithm and numerical results of test functions were reported.Conclusions were drawn in the end.  相似文献   

3.
By using the properties of nonnegative matrices and techniques of differential inequalities, some sufficient conditions for the global exponential stability of cellular neural networks with time delays were obtained. The criteria do not require such conditions as boundedness and differentiability of activation functions. The conditions of the theorem were verified.  相似文献   

4.
In this paper,the nonlinear Schrodinger(NLS)equation was analytically solved.Firstly,the stationary solutions of NLS equation were explicitly given by the elliptic functions.Then a family of exact solutions of NLS equation were botained from these stationary solutions by a method for finding new exact solutions from the stationary solutions of integrable evolution equations.  相似文献   

5.
Dec 10 1804 - Feb 18 1851Born Potsdam, Germany. Died Berlin, Germany.Jacobi founded the theory of elliptic functions. Jacobi's father was a banker and his family were prosperous so he received a good education at the University of Berlin. He obtained his Ph.D. in 1825 and taught mathematics at the University of K?nigsberg from 1826 until his death, being appointed to a chair in 1832. He founded the theory of elliptic functions based on four theta functions. His "Fundamenta nova theoria f…  相似文献   

6.
This study explored the potential of using probabilistic neural networks (PNN) to predict shrinkage of thermal insulation mortar.Probabilistic results were obtained from the PNN model with the aid of Parzen non-parametric estimator of the probability density functions (PDF).Five variables,water-cementitious materials ratio,content of cement,fly ash,aggregate and plasticizer,were employed for input variables,while a category of 56-d shrinkage of mortar was used for the output variable.A total of 192 groups of experimental data from 64 mixtures designed using JMP7.0 software were collected,of which 120 groups of data were used for training the model and the other 72 groups of data for testing.The simulation results showed that the PNN model with an optimal smoothing parameter determined by the curves of the mean square error (MSE) and the number of unrecognized probability densities (UPDs) exhibited a promising capability of predicting shrinkage of mortar.  相似文献   

7.
This study focuses on the evaluation of the differences of physical fitness among soccer players, handball players, and basketball players, and the investigation of the physical fitness structures of those players. The participants consisted of 160 elite players selected from university teams. Fourteen tests related to health and motor fitness were conducted. The results were subjected to a multivariate analysis of variance (MANOVA) to test the mean vector differences among the three groups of different sport. Nine out of the fourteen tests were of significantly discriminating results regarding to different group, which include side step, abdominal strength, shuttle running, 100m running, pull-up, 1,500m running, trunk flexion, grip strength and broad jump, as determined by a stepwise regression approach. MANOVA showed that there was a significant difference (p< 0.001) of the mean vectors of the 9 tests among the three events. Discriminant function analysis showed that three discriminant functions were s  相似文献   

8.
The objective of this study was to investigate the endosonographic appearance of gastric linitis plastica(GLP) and to study the usefulness of endoscopic ultrasonography(EUS) for the T and N staging of GLP.EUS examinations of 55 patients with histologically proven GLP were retrospectively studied.In all patients,EUS showed that lesions involved at least one-third of the circumference of the stomach.Based on the findings of the EUS,the 55 patients were divided into two groups.There were 32(58.2%) patients in the first group.EUS of this group showed that the five sonographic layers had disappeared and had been replaced by a hypoechogenic thickening of the gastric wall.There were 23(41.8%) patients in the second group.EUS of this group showed that the first three sonographic layers were blurred and thickened,and the fourth layer was significantly thickened.The full thickness of the gastric wall was significantly thicker in first than in the second group of patients(P<0.01).The incidence of perigastric lesions was significantly higher in the first than in the second group of patients(P<0.01).Results for the 15 patients following preoperative EUS were compared postoperatively with histopathologic findings for T and N staging.The overall diagnostic accuracy of the T stage was 73.3% and of the N stage was 60.0%.In eight patients,we used EUS to assess a therapeutic response.No response was observed in five patients and a partial response in three.EUS images of GLP are characteristic.EUS is helpful in diagnosing GLP and for assessing the T and N stages.  相似文献   

9.
It is demonstrated that if the vector sum of the external forces and the total external torque are functions of all the positions and the velocities of the particles, the internal forces will affect indirectly the linear momentum and the angular momentum of a system of the particles through the and. In order to ensure that the internal forces have no effect on the and of the system, the external forces must be restricted to a linear function of and. Some examples which show that internal forces do affect the motion of the center of mass and the angular momentum of the system were discussed.  相似文献   

10.
This paper is focused on the Marangoni effect in the gas-liquid mass transfer systems. A series of experiments were conducted to observe Marangoni effect by a laser Schlieren system. Experimental investigations of the occurrence of Marangoni convection were presented. The typical polygonal patterns and even the reaching of chaotic interfacial flow were observed. The visual evidences were discussed and the characteristic time and scale of Marangoni convection were obtained approximately as 0.5 s and 1 mm according to the Schlieren images. From the perspective of hydrodynamic instability, the mechanism of the Marangoni convection was investigated. Though many external factors have influence on the interfacial instability, the local surface-tension gradient is the primary reason for the Marangoni convection. The small-scale interfacial flow increases the surface renewal rate. Consequently, due to the occurrence of the Marangoni effect, the mass transfer rate can be significantly enhanced.  相似文献   

11.
Molecular dynamics (MD) simulations were performed to investigate the glass forming ability (GFA) and microscopic structural properties of liquid Cu-Zr alloys. Based on the analysis of composition dependences of the reduced glass transition temperatures and the excess volume, we found that the Cu-Zr glasses have the largest GFA at Cu65Zr35 composition. To get more detailed information of local structure, we calculated the pair correlation functions, partial pair correlation functions, the excess entropy, chemical order parameter, coordination number, and Voronoi index of Cu-Zr liquids. We found that there exists an obvious and close relationship among the GFA, the excess entropy calculated using the total pair correlation functions, chemical order parameters, and some Cu centered cluster with Voronoi index <0,2,8,1> and Zr centered cluster with Voronoi index <0,3,6,4>, which all have nonlinear dependences on Cu/Zr concentration and have extreme values at liquid Cu65Zr35 composition.  相似文献   

12.
The influence of direct quenching (DQ) on microstructure and mechanical properties of 0.19C-1.7Si-1.0 Mn-0.05Nb steel was studied. The microstructure and mechanical properties of reheat quenched and tempered (RQ&T) steel plate were compared with those of direct quenched and tempered (DQ&T) steel plates which were hot rolled at different finish rolling tem-peratures (1173 K and 1123 K), i.e., recrystallization-controlled-rolled direct-quenched (RCR&DQ) and controlled-rolled direct-quenched (CR&DQ), respectively. The strengths generally increased in the following order: RQ&T〈RCR&DQ&T〈 CR&DQ&T. Strength differences between the CR&DQ&T and RQ&T conditions as high as 14% were observed at the tempered temperature of 573 K. The optical microscopy of the CR&DQ&T steel showed deformed grains elongated along the rolling direction, while complete equiaxed grains were visible in RQ&T and RCR&DQ&T steels. Transmission electron microscopy (TEM) and electron backscattering diffraction (EBSD) of the DQ steels showed smaller block width and higher density of dislocations. Inheritance of austenite deformation substructure by the martensite and differences in martensite block width were ruled out as major causes for the strength differences between DQ and RQ steels.  相似文献   

13.
从代数的结构和映射的特征出发,研究了套代数上的局部φ-导子,证明了套代数上的任意范数连续的线性局部φ-导子都是φ-导子,推广了已有的结论.  相似文献   

14.
This paper presents an empirical study of move structures and personal pronouns of fifty English RA (research article) abstracts based on the model of Bhatia (1990). It revealed that three other move patterns were ascertained besides ten out of the analyzed abstracts following his move order. The analysis of personal pronouns showed that first-person plural pronouns are used far more frequently than other types of personal pronouns and no presence of the second-person and the third-person pronouns were detected in the abstracts. A further analysis suggests that first-person plural pronouns can perform multiple functions in abstracts. ESP (English as Special Purpose) teachers may benefit from the study to guide students to explore the discourse conventions of the RA abstracts in their own texts.  相似文献   

15.
The precise etiology and reasons for the increase in incidence of autoimmune disorders still remain unclear, and although both genetic and environmental factors have been proven to shape individual predisposition, it is not known which of the factors, if not both, is responsible for the boom observed during the last decades. In order to establish whether a higher frequency of autoimmune-predisposing alleles may explain this increase we took advantage of ancient DNA methodology to establish the genetic predisposition, conferred by cytotoxic T lymphocyte associated antigen-4 (CTLA4) +49A/G and human leukocyte antigens (HLA) DQBI^57, in population inhabiting Poland in the Middle Ages. After successful typing of 42 individuals from a 12th-14th's century archeological burial site, we found that frequencies of the predisposing alleles in the medieval population were higher than they are at present, suggesting thus that the recently observed incidence increase results most probably from factors of other than genetic nature.  相似文献   

16.
A series of metal chlorides supported solid catalysts were prepared by simple wet impregnation method. Their catalytic performances for Friedel-Crafts acylation of toluene with benzoyl chloride were evaluated and the excellent results were obtained over Fe Cl3/Si O2. These catalysts were characterized by BET, NH3-TPD and FT-IR of pyridine adsorption to clarify the structure-activity relationship. It was found that Fe Cl3/Si O2 has larger pore size and pore volume than other catalysts, which increased the accessibility of the catalyst. In addition, Fe Cl3/Si O2 exhibited higher molar ratio of Lewis acid sites and Brφnsted acid sites, which might be another reason for the increase of toluene conversion. Furthermore, the reaction parameters, including temperature, time and molar ratio, were optimized. Under the optimized conditions, 91.2%, conversion and 82.0%, selectivity were obtained. Meanwhile, the generality of the catalyst was demonstrated by the acylations of alkyl substituted aromatics. Finally, the catalyst was reused for four runs with slight loss in catalytic activity, which attributed to the drain of the active component.  相似文献   

17.
The ring-shaped oscillator potential, obtained by replacing the Coulomb part of the Hartmann potential by a harmonic oscillator term, was investigated. Under the equal vector potential and scalar potential, the Dirac equation was solved in spherical coordinate. The exact energy spectrum of the bound states was presented as a solution to the confluent hypergeometric equation by boundary conditions. Furthermore, the normalized angular and radial wave functions were presented.  相似文献   

18.
For the sequences satisfying the recurrence relation of the second order,the generating functions for the products of the powers of these sequences are established.This study was from Carlita and Riordan who began a study on closed form of generating functions for powers of second-order recurrence sequences.This investigation was completed by Stnica.Inspired by the recent work of Istva'n about the non-closed generating functions of the products of the powers of the second-order sequences,the authors give s...  相似文献   

19.
With the terms of the exact series solution taken as trial functions, the method of point collocation was used to calculate the large deflection of a circular plate. The axisymmetrical bending formulae were developed for the calculation of a circular plate subjected to polynomial distributed loads, a concentrated load at the center, uniform radial forces and moments along the edge or their combinations. The support may be elastic. The buckling load was calculated. Under action of uniformly distributed load, central load or their compound load, solutions were compared with those obtained by other methods, Buckling beyond critical thrust was compared with that calculated by the power series method. The method presented in this paper has advantages of wide convergent range, high precision and short computing time. Moreover, the computing time is nearly independent of the complexity of the loads.  相似文献   

20.
This paper presents a new design of robust optimal controller for multivariable system. The row characteristic functions of a linear multivariable system and dynamic decoupling of its equivalent system, were applied to change the transfer function matrix of a closed-loop system into a normal function matrix, so that robust H∞optimal stability is guaranteed. Furthermore, for the decoupled equivalent control system the l∞optimization approach is used to have the closed-loop system embody optimal time domain indexes. A successful application on a heater control system verified the excellence of the new control scheme.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号