共查询到20条相似文献,搜索用时 46 毫秒
1.
When using H∞ techniques to design decentralized controllers for large systems,the whole system is divided into subsystems, which are analysed using H∞ control theorybefore being recombined. An analogy was established with substructural analysis instructural mechanics, in which H∞ decentralized control theory corresponds to substructuralmodal synthesis theory so that the optimal H∞ norm of the whole system corresponds to thefundamental vibration frequency of the whole structure. Hence, modal synthesismethodology and the extended Wittrick-Williams algorithm were transplanted from structuralmechanics to compute the optimal H∞ norm of the control system. The orthogonality and theexpansion theorem of eigenfunctions of the subsystems H∞ control are presented in part(I) of the paper. The modal synthesis method for computation of the optimal H∞ norm ofdecentralized control systems and numerical examples are presented in part (Ⅱ). 相似文献
2.
When using H∞ techniques to design decentralized controllers for large systems, the whole system is divided into subsystems, which are analysed using H∞ control theorybefore being recombined. An analogy was established with substructural analysis instructural mechanics, in which H∞ decentralized control theory corresponds to substructuralmodal synthesis theory so that the optimal H∞ norm of the whole system corresponds to thefundamental vibration frequency of the whole structure. Hence, modal synthesismethodology and the extended Wittrick-Williams algorithm were transplanted from structuralmechanics to compute the optimal H∞ norm of the control system. The orthogonality and theexpansion theorem of eigenfunctions of the subsystems H~ control are presented in part (I)of the paper. The modal synthesis method for computation of the optimal H∞ norm ofdecentralized control systems and numerical examples are presented in part (Ⅱ). 相似文献
3.
TheT
ε
*
integral was calculated on the surface of single edge notched, three-point bend (SE(B)) specimens using experimentally obtained
displacements. Comparison was made withT
ε
*
calculated with the measured surface displacements andT
ε
*
calculated at several points through the thickness of a finite element (FE) model of the SE(B) specimen. Good comparison
was found between the surfaceT
ε
*
calculated from displacements extracted from the FE model and the surfaceT
ε
*
calculated from experimentally obtained displacements. The computedT
ε
*
integral was also observed to decrease as the crack front was traversed from the surface to the mid-plane of the specimen.
Mid-planeT
ε
*
values tend to be approximately 10% of the surface values. 相似文献
4.
Yu. A. Abzaev 《Journal of Applied Mechanics and Technical Physics》2007,48(4):599-604
The temperature dependence of the yield stress τ*
Ni
3
Ge single crystals is studied. The temperature dependence τ*(T) in the high-temperature region (above 420 K) is found to be conditioned by thermally activated accumulation of the density of non-screw components of superdislocations.
Interaction of point defects with edge dislocations and its effect on the temperature anomaly of the yield stress in Ni
3
Ge single crystals are analyzed. The calculated results are found to agree with experimental data.
__________
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 4, pp. 154–161, July–August, 2007. 相似文献
5.
Ding Xie-ping 《应用数学和力学(英文版)》2003,24(9):1017-1024
By applying existence theorems of maximal elements for a family of GB-majorized mappings in a product space of G-convex spaces, some coincidence theorem, Fan-Browder type fixed point theorem
and some existence theorems of solutions for a system of minimax inequalities are proved under noncompact setting of G-convex
spaces. These theorems improve and generalize many important known results in literature.
Contributed by Duping Xie-ping
Foundation items: the National Natural Science Foundation of China (19871059); the Natural Science Foundation of Education Department of Sichuan
Province ([2000]25)
Biography: Duping Xie-ping (1938∼), Professor (E-mail: dingxip@sichu.edu.cn) 相似文献
6.
Ding Xie-ping 《应用数学和力学(英文版)》2003,24(6):659-672
A new family of set-valued mappings from a topological space into generalized convex spaces was introduced and studied. By
using the continuous partition of unity theorem and Brouwer fixed point theorem, several existence theorems of maximal elements
for the family of set-valued mappings were proved under noncompact setting of product generalized convex spaces. These theorems
improve, unify and generalize many important results in recent literature.
Contributed by DING Xie-ping
Foundation items: the National Natural Science Foundation of China (19871059); the Natural Science Foundation of Education Department of Sichuan
Province of China ([2000]25)
Biography: DING Xie-ping (1938∼) 相似文献
7.
This paper presents the numerical study of internal free convection of Al2O3 water nanofluid in vertical annuli. Vertical walls are maintained at constant temperatures and horizontal walls are adiabatic.
Results are validated by experimental data. Effect of nanofluids on natural convection is investigated as a function of geometrical
and physical parameters and particle fractions for aspect ratio of 1 ≤ H/L ≤ 5, Grashof number of 103 ≤ Gr ≤ 105 and concentration of 0 ≤ ϕ ≤ 0.06. More than 330 different numerical cases are investigated to develop a new correlation for the Nusselt number. This
correlation is presented as a function of Nusselt number of base fluid and particle fraction which is a linear decreasing
function of particle fraction. The developed correlation for annuli is also valid for the natural convection of Al2O3 water nanofluid in a square cavity. Furthermore, the effect of the viscosity and conductivity models on the Nusselt number
of nanofluids in cylindrical cavities are discussed. 相似文献
8.
Petty's conjectured projection inequality is a famous open problem in the theory of convex bodies. In this paper, it is shown that an inequality relating to Lp-version of the Petty's conjectured projection inequality is developed by using the notions of the Lp-mixed volume and the Lp-dual mixed volume, the relation of the Lp-projection body and the geometric body Г-pK, the Bourgain-Milman inequality and the Lp-Bnsemann-Petty inequality. In addition, for each origin-symmetric convex body, by applying the Jensen inequality and the monotonicity of the geometric body Г-pK, the reverses of Lp-version of the Petty's conjectured projection inequality and the Lp-Petty projection inequality are given, respectively. 相似文献
9.
In this paper, a non-isobaric Marangoni boundary layer flow that can be formed along the interface of immiscible nanofluids
in surface driven flows due to an imposed temperature gradient, is considered. The solution is determined using a similarity
solution for both the momentum and energy equations and assuming developing boundary layer flow along the interface of the
immiscible nanofluids. The resulting system of nonlinear ordinary differential equations is solved numerically using the shooting
method along with the Runge-Kutta-Fehlberg method. Numerical results are obtained for the interface velocity, the surface
temperature gradient as well as the velocity and temperature profiles for some values of the governing parameters, namely
the nanoparticle volume fraction φ (0≤φ≤0.2) and the constant exponent β. Three different types of nanoparticles, namely Cu, Al2O3 and TiO2 are considered by using water-based fluid with Prandtl number Pr =6.2. It was found that nanoparticles with low thermal conductivity,
TiO2, have better enhancement on heat transfer compared to Al2O3 and Cu. The results also indicate that dual solutions exist when β<0.5. The paper complements also the work by Golia and Viviani (Meccanica 21:200–204, 1986) concerning the dual solutions in the case of adverse pressure gradient. 相似文献
10.
A new class of g-η-monotone mappings and a class of generalized implicit variational-like inclusions involving g-η-monotone mappings are introduced. The resolvent operator of g-η-monotone mappings is defined and its Lipschitz continuity is presented. An iterative algorithm for approximating the solutions of generalized implicit variational-like inclusions is suggested and analyzed. The convergence of iterative sequences generated by the algorithm is also proved. 相似文献
11.
Nylon-6 is an important engineering polymer that, in its fully spherulitic (bulk) form, has many applications in gears, rollers,
and other long life cycle components. In 1993, Toyota commercialized a nylon-6/clay nanocomposite out of which it produced
the timing belt cover for the Camry. Although these hybrid nanocomposites show significant improvements in their mechanical
response characteristics, including yield strength and heat distortion temperature, little is known about the degradation
of these properties due to environmental pollutants like NO
x
. Nylon-6 fibers are severely degraded by interaction with NO
x
and other pollutants, showing a strong synergy between applied load and environmental degradation. While the nanocomposites
show a significant reduction in permeability of gases and water due to the incorporation of lamellar clay, their susceptibility
to nondiffusional mechano-chemical degradation is unknown. The fracture toughness of these nylon-6/clay nanocomposites increases,
not as a function of clay content, but as a function of the volume of nylon-6 polymer chains influenced by the clay lamellae
surfaces. Both the clay and the constrained volume offer the nanocomposites some protection from the deleterious effects of
NO
x
. The time-to-failure at a given stress intensity factor as a function of clay content and constrained volume is discussed
along with fracture toughness of the materials. 相似文献
12.
13.
HOUJian 《应用数学和力学(英文版)》2004,25(6):694-702
According to the research theory of improved black oil simulator, a practical mathematical model for C02 miscible flooding was presented. In the model, the miscible process simulation was realized by adjusting oil/gas relative permeability and effective viscosity under the condition of miscible flow. In order to predict the production performance fast, streamline method is employed to solve this model as an alternative to traditional finite difference methods. Based on streamline distribution of steady-state flow through porous media with complex boundary confirmed with the boundary element method (BEM), an explicit total variation diminishing (TVD) method is used to solve the one-dimensional flow problem. At the same time, influences of development scheme, solvent slug size, and injection periods on CO2 drive recovery are discussed. The model has the advantages of less information need, fast calculation, and adaptation to calculate CO2 drive performance of all kinds of patterns in a random shaped porous media with assembly boundary. It can be an effective tool for early stage screening andmiscible oil field.reservoir dynamic management of the CO2 miscible oil field. 相似文献
14.
丁协平 《应用数学和力学(英文版)》2007,28(12):1569-1579
This paper is a continuum of the preceding paper of author. Some new systems of generalized vector quasi-equilibrium problems
involving condensing mappings are introduced and studied in locally FC-uniform spaces. By applying the existence theorem of maximal elements of condensing set-valued mappings in locally FC-uniform spaces obtained by author in the preceding paper, some new existence theorems of solutions for the systems of generalized
vector quasi-equilibrium problems are proved in locally FC-uniform spaces. These results improve and generalize some known results in literature to locally FC-uniform spaces.
Project supported by the Natural Science Foundation of Sichuan Education Department of China (No. 2003A081 and SZD0406) 相似文献
15.
Choon Ki Ahn 《Nonlinear dynamics》2010,62(3):543-552
This paper proposes a new neural network ℋ∞ synchronization (NNHS) scheme for unknown chaotic systems. In the proposed framework, a dynamic neural network is constructed
as an alternative to approximate the chaotic system. Based on this neural network and linear matrix inequality (LMI) formulation,
the NNHS controller and the learning law are presented to reduce the effect of disturbance to an ℋ∞ norm constraint. It is shown that finding the NNHS controller and the learning law can be transformed into the LMI problem
and solved using the convex optimization method. A numerical example is presented to demonstrate the validity of the proposed
NNHS scheme. 相似文献
16.
The main purpose of this paper is to study a new iterative algorithm for finding a common element of the set of solutions for a generalized equilibrium problem and the set of fixed points for a k-strict pseudocontractive mapping in the Hilbert space. The presented results extend and improve the corresponding results reported in the lit-erature. 相似文献
17.
First of all, the concept of γ-p-Sa-Sm-N (confidence level-relabilitystress amplitude-stress mean-fatigue life) surface is presented. Then the formulas of p-Sa-Sm-N surface and γ-p-Sa-Sm-N surface are derived. In addition, fatigue strength distribution function and two-dimensional reliability Miner rule are
obtained. At last, an example is given.
Foundation item: the National Natural Science Foundation of China (19672051) 相似文献
18.
A class of nonlinear boundary value problems (BVP) for the second-order E2 class elliptic systems in general form is discussed. By introducing a kind of transformation, this kind of BVP is reduced
to a class of generalized nonlinear Riemann-Hilbert BVP. And then some singular integral operators are introduced to establish
the equivalent nonlinear singular integral equations. The solvability is proved under some suitable hypotheses by means of
the properties of singular integral operators and the function theoretic methods.
Foundation items: the National Natural Science Foundation of China (19671056); Shanghai Municipal Natural Scientific Foundation (99ZA14030,
01ZA14023); Jiangxi Provincial Natural Scientific Foundation (981102, 0211014)
Biographies: LI Ming-zhong (1935−); XU Ding-hua (1967−) 相似文献
19.
Effects of the stress state on plasticity and ductile failure of an aluminum 5083 alloy 总被引:2,自引:0,他引:2
Xiaosheng Gao Tingting Zhang Matthew Hayden Charles Roe 《International Journal of Plasticity》2009,25(12):2366-2382
The experimental and numerical work presented in this paper reveals that stress state has strong effects on both the plastic response and the ductile fracture behavior of an aluminum 5083 alloy. As a result, the hydrostatic stress and the third invariant of the stress deviator (which is related to the Lode angle) need to be incorporated in the material modeling. These findings challenge the classical J2 plasticity theory and provide a blueprint for the establishment of the stress state dependent plasticity and ductile fracture models for aluminum structural reliability assessments. Further investigations are planned to advance, calibrate and validate the new plasticity and ductile fracture models. 相似文献
20.
This paper investigates robust filter design for linear discrete-time impulsive systems with uncertainty under H∞ performance. First, an impulsive linear filter and a robust H∞ filtering problem are introduced for a discrete-time impulsive systems. Then, a sufficient condition of asymptotical stability and H∞ performance for the filtering error systems are provided by the discrete-time Lyapunov function method. The filter gains can be obtained by solving a set of linear matrix inequalities (LMIs). Finally, a numerical example is presented to show effectiveness of the obtained result. 相似文献