Adaptive backstepping sliding mode control for nonlinear systems with input saturation

An adaptive backstepping sliding mode control is proposed for a class of uncertain nonlinear systems with input saturation.A command filtered approach is used to prevent input saturation from destroying the adaptive capabilities of neural networks (NNs).The control law and adaptive updating laws of NNs are derived in the sense of Lyapunov function,so the stability can be guaranteed even under the input saturation.The proposed control law is robust against the disturbance,and it can also eliminate the impact of input saturation.Simulation results indicate that the proposed controller has a good performance.     

Control synthesis for polynomial nonlinear systems and application in attitude control

A method for positive polynomial validation based on polynomial decomposition is proposed to deal with control synthesis problems. Detailed algorithms for decomposition are given which mainly consider how to convert coefficients of a polynomial to a matrix with free variables. Then, the positivity of a polynomial is checked by the decomposed matrix with semidefinite programming solvers. A nonlinear control law is presented for single input polynomial systems based on the Lyapunov stability theorem. The control synthesis method is advanced to multi-input systems further. An application in attitude control is finally presented. The proposed control law achieves effective performance as illustrated by the numerical example.     

WPT-based modal control on distributed structures with MRF-04K damper

The magnetorheological (MR) fluid damper-based semiactive control systems have received considerable attention for protecting structures against natural hazards such as strong earthquakes and high winds. In this paper, a novel modal controller using wavelet packet transform (WPT) is proposed for the vibration control of distributed structures. In the proposed control system, the WPT method is utilized to decompose the acceleration measurement and select the modes containing most of the WPT energy component as the dominant modes. Then, a modal controller is designed to control the dominant modes and the optimal active control force is solved. Finally, Clipped-optimal con- trol law is adopted to determine the voltage applied to each MR damper. A Kalman-filter observer, which estimates the full controlled modal states from local accelerometer feedbacks, is designed for rendering the controller to be more applicable to distributed structures with a large number of degrees of freedom. A numerical example of a stadium roof structure installed with MRF-04K damper is presented. The effectiveness of the controller is evaluated under both Tianjin and El Centro earthquake excitations. The superior performance and adaptability of the controller for versatile loading conditions are demonstrated through the comparison with traditional truncated modal controller.     

E-mail（初三适用）

Are you able to send a letter with pictures and sounds to someone, anywhere in the world without putting a stamp on it? With e-mail you can just do that. Electronic mail (e-mail) is a way of sending messages to other people. Using a computer you can send e-mail quickly and easily. The post is much slower and dearer than e-mail. E-mail can send its message to the other side of the world in seconds.     

Fatigue and fracture behavior of nickel-based superalloy Inconel 718 up to the very high cycle regime

The fatigue and fracture behavior of nickel-based superalloy Inconel 718 was investigated up to the very high cycle regime under rotary bending tests at room temperature. It was found that this superalloy can still fracture after exceeding 107 cycles. Fractographic analysis revealed that there was a transition from fatigue crack initiation at multi-sites to single initiation with decreasing stress levels. The fracture surface can be divided into four areas according to the appearance, associated with fracture mechanics analysis of the corresponding stress intensity factors. The fracture mechanism dominant in each area was disclosed by scanning electron microscope examination and analyzed in comparison with those obtained from the crack growth tests. Subsequently, life prediction modeling was proposed by estimating the crack initiation and propagation stage respectively. It was found that Chan （2003）＇s model for initiation life and the Paris law for growth life can provide comparable predictions against the experimental life.     

On the Pilgrim to “A Room of One’s Own” in The Hours

In A Room of One’s Own,Virginia Woolf argued her famous proposition that a woman needed to have a room of her own to achieve literary autonomy,and laid the foundation for present-day feminist criticism.Yet the author believes that economic independent does not foster women’s identity with certainty.In this thesis,the author explores the crucial place of spiritual and economic independence in building up women’s autonomy through analyzing Michael Cunningham Pulitzerwinning work The Hours,which he draws inventively on the life of Virginia Woolf and her work Mrs.Dalloway.     

Evaluation of the effective thermal conductivity of composite polymers by considering the filler size distribution law

We present an empirical model for the effective thermal conductivity （ETC） of a polymer composite that includes dependency on the filler size distribution-chosen as the Rosin-Rammler distribution. The ETC is determined based on certain hypotheses that connect the behavior of a real composite material A, to that of a model composite material B, filled with mono-dimensional filler. The application of these hypotheses to the Maxwell model for ETC is presented. The validation of the new model and its characteristic equation was carried out using experimental data from the reference. The comparison showed that by using the size distribution law a very good fit between the equation of the new model （the size distribution model for the ETC） and the reference experimental results is obtained, even for high volume fractions, up to about 50%.     

Damage assessment for buried structures against internal blast load

The soil-structure interaction (SSI) decoupling is applied to simplify buried structure against internal blast load as spring effect. Shear failure, bending failure and combined failure modes are considered based on five transverse velocity profiles for the rigid-plastic structural element. The critical equations for shear and bending failure are derived respectively. Pressureimpulse diagrams are accordingly developed to assess damage of the buried structures against internal blast load. Comparison is done to show influences of soil-structure interaction and shear-to-bending strength ratio of a structural element. A case study is conducted to show the application of damage assessment to a reinforced concrete beam element of buried structure.     

Atmospheric corrosion mapping of copper surfaces from diffuse light scattering measurements by an optoelectronic sensor system

A novel light scattering technique for mapping metal surface corrosion is presented and its results on copper exposed to atmosphere are reported. The front end of the instrument is made up of a sensor module comprising a thin beam light emitting diode （LED） illuminating a small spot on the metal surface, and a matched pair of photodetectors, one for capturing the reflected light and the other for sampling the scattered light. The analog photocurrent signals are digitized and processed online by a per- sonal computer （PC） to determine the corrosion factor defined in terms of the two current values. By scanning the sample surface using the light beam and by computing the corrosion factor values simultaneously, a three dimensional graph and a two dimensional contour map are generated in the PC using Matlab tools. The values of the corrosion factor measured in different durations of exposure to atmosphere, which obey a bilogarithmic law, testify to the validity of our mathematical model.     

The English Revolution and a Representative and Constitutional Government

This article gives a brief introduction to the English Revolution and describes a detailed study of influence, as well as the explanation of a representative and constitutional government. The English Revolution which happened in Britain is a historical event of great influence. It abolished the autarchic system of king and began to rule the society by law. We can conclude that it created good political conditions for Britain to become a kingdom of modern civilization.     

Velocity distribution and scaling properties of wall bounded flow

The scaling and similarity of wall bounded turbulent flow were studied. The properties of such flows and the relationship between a power law and a logarithmic type of velocity distribution were investigated. Based on the physical mechanism involved, our results show that the power law and the logarithmic distribution are only different forms with the same hypothesis and hold only in the outer flow zone. Thus, a universal explanation for various empirical formulae of velocity distribution was obtained. Manning＇s formula was studied to explain theoretically the experiential result that the roughness coefficient is only a comprehensive parameter of the whole system without a corresponding physical factor. The physical mechanism of the velocity distribution of parallel to wall bounded flow was explored, the results show that the parameters in the formula of velocity distribution are indices of the system responding to flowing environmental factors to represent general case of boundary roughness and the flowing state, corresponding physical mechanism is vortex motion.     

The Moore＇s Law for photonic integrated circuits

We formulate a ＂Moore＇s law＂ for photonic integrated circuits （PICs） and their spatial integration density using two methods. One is decomposing the integrated photonics devices of diverse types into equivalent basic elements, which makes a comparison with the generic elements of electronic integrated circuits more meaningful. The other is making a complex component equivalent to a series of basic elements of the same functionality, which is used to calculate the integration density for functional components realized with different structures. The results serve as a benchmark of the evolution of PICs and we can conclude that the density of integration measured in this way roughly increases by a factor of 2 per year. The prospects for a continued increase of spatial integration density are discussed.     

Retrofitting of RC Slabs Against Explosive Loads

With the increase of terrorist bomb attacks on buildings, there is a need to develop advanced retrofitting techniques to strengthen structures against blast loads. Currently, several guidelines including an Australian version for retrofitting reinforced concrete (RC) structures are available for the design of retrofitting systems against seismic and monotonic loads using steel or fibre reinforced polymer (FRP) plates that can be either adhesively bonded to the surface or near surface mounted to the concrete cover. However, none of these guidelines provide advice suitable for retrofitting structures subjected to blast loads. In this paper, numerical models are used to simulate the performance of retrofitted RC slabs subjected to blast loads. Airblast pressure distributions on the surface of the slabs estimated in a previous study are used as input in the analysis. A material damage model developed previously for concrete and an elastoplastic model for steel bars are employed in this research for modelling reinforced concrete behaviour due to explosive loads. The material models and blast loading are coded into a finite element computer program LS-DYNA3D to do the analysis. With the numerical model, parametric studies are conducted to investigate RC slabs retrofitted by either externally bonded or near-surface mounted plates or GFRP sheets subjected to blast loads. Discussion is made on the effectiveness of the retrofitting system for RC slabs against blast loads.     

A new neural network model for the feedback stabilization of nonlinear systems

A new neural network model termed ＇standard neural network model＇ （SNNM） is presented, and a state-feedback control law is then designed for the SNNM to stabilize the closed-loop system. The control design constraints are shown to be a set of linear matrix inequalities （LMIs）, which can be easily solved by the MATLAB LMI Control Toolbox to determine the control law. Most recurrent neural networks （including the chaotic neural network） and nonlinear systems modeled by neural networks or Takagi and Sugeno （T-S） fuzzy models can be transformed into the SNNMs to be stabilization controllers synthesized in the framework of a unified SNNM. Finally, three numerical examples are provided to illustrate the design developed in this paper.     

“画蛇”并非“添足”

1.The Chinese rose up against the foreign invaders.2.Now,let's enter into conversation.3.We should prepare for trouble.4.The nurses are attending to the patient.5.The room can serve us for a lab.6.She asked me if I had found out the truth.7. We went to the cinema after a quick supper.8.Tom,please join in the game.9.Her parents promised that if she would pass the exam,they could buy him a new bicycle.10.A little child as he is,he can lift the heavy box.     

We Have Our Own Way of Education

On June I7, 1744, the officials from Maryland and Virginia held a talk with the Indians of the Six Nations. The Indians were invited to send boys to William and Mary College. In a letter the next day they refused the offer as follows:     

Analysis of Modernist Concept of Time and Consciousness in The Mark on the Wall

The Mark on the Wall by Virginia Woolf mirrors the features of modernists’ fictions.By a close analysis of the smart use of mixed tenses as well as the "stream of consciousness" technique in the short story,the paper exemplifies Woolf’s unique writing style,an innovation against the traditional narrative devices.     

高中三册第4单元练习(英文)

Ⅰ.单项填空 1. Nowadays, some stars like ____ because they can ____ a lot of money. A. advertisements; bring B. advertising; make C. to advertise; earn D. making advertisement; make 2. ——Who is to ____ for the accident, you or I? ——I don9t know. A. scold B. be blamed C. blame D. criticize 3. The old man was sentenced ____ for 10 years but he appealed ____ another court. A. in the prison; over B. in prison; to C. at the prison; against D. in a prison; against 4. The little boy was sen…     

一个伟人的同情心

It was a bitter cold evening in northern Virginia many years ago,The old man's beard was glazed by winter's frost while he waited for a ride across the river. The wait seemed endless. His body became numb and stiff from the frigid north wind.     

Credit risk constraint mechanisms in rural financial reform

To research the operating mechanisms of rural financial reform, through setting up a contract model, the constraint roles of reputation and legal intervention on the default risk arising in the operating of the credit union funds are inspected. Analysis indicates that the increase in reputation cost can reduce the probability of union member default behavior and the probability of turning to the law for the credit union funds. Meanwhile, the amount of loans and the interest rates can increase the probability of turning to the law for the credit union funds. Below the marginal values, the penalty mechanisms can reduce the balancing probabilities of member default behavior and turning to the law for the credit union funds, namely, the penalty has some "substitution effect" for turning to the law for the credit union funds.