Applied Mechanics and Materials Vols. 48-49

Abstract: This brief investigates the stability problem of discrete-time switched positive systems with delays, and establishes some necessary and sufficient conditions for the existence of a switched copositive Lyapunov function(SCLF) for such systems. It turns out that the size of the delays does not affect the stability of these systems. In other words, system stability is completely determined by the system matrices.

Abstract: This paper considers a regulation problem for discrete-time switched bimodal linear systems. First, a set of observer-based -parameterized stabilizing controllers for the switched system is constructed. Then, a regulator synthesis method is proposed based on solving a set of linear matrix inequalities which is derived from a regulation condition for the switched system. Finally, a numerical example is presented to illustrate the effectiveness of the proposed design method.

Abstract: This paper is concerned with closed-loop stability analysis and dynamic quantization parameters design of discrete-time networked control systems (NCSs) with noise disturbance. First, based on the Lyapunov function, two state invariant regions of estimation error system and plant system are constructed. The quadratically attractive conditions of the two systems are obtained by using the proposed invariant region sequence, respectively. Second, a quantized control strategy is presented by dynamically adjusting the scaling parameters of logarithmic quantizers. Moreover, the connection of quadratic stability between the plant system and the estimation error system is also given.

Abstract: Based on finite element theory, pillar structure of the model parameters was established, and analyzed its static and dynamic performance. At the same time, the structural deformation of pillar load and deformation characteristics were analyzed. The choosing shape method was used to get the improvements in pillar. The Improved models were done modal analysis, and got their natural frequencies.

Abstract: A static output feedback (SOF) control schemes are proposed. The basic idea of it is to construct piecewise quadratic Lyapunov function and introduce a dissipation inequality to guarantee the system energy dissipation. It is shown that the controller analysis or the synthesis problem can be casted as convex optimization problem, and the controller can be obtained by solving a set of linear matrix inequalities. The designed controllers not only guarantee the stability of the closed-loop systems, but also obtain the disturbance attenuation ability.

Abstract: Establishment of one process and some ameliorations of decision tree’s algorithm in order to predict the second day’s price change. The experiment builds a J48 tree, which is comfortable with continuous attributes, based on 10 years historical stock prices. After careful selection and preprocessing of financial data, high prediction accuracy is obtained. An introduction of dynamic-constructed tree reduces tree’s cost, and increases prediction’s quality on accuracy as well as average error distance.

Abstract: In order to solve the damage detection problem, a damage detection method based on strain energy and evidence theory is presented in this paper. First, an evidence theory method is proposed to identify structural damage locations. Then, structural modal strain energy is utilized to quantify structural damage extents. In general, structural strain energy dissipation should be equal to the change of modal strain energy, according to this theory, a new energy equation is deduced, and structural damage extent can be obtained through the solution of the equation. The simulation results show that the method can perfectly identify damage locations and extents. Therefore, the proposed method is effective for the structural damage identification.

Abstract: Following the previous study [Chemistry Letters 2007, 10, 1278.] on specific electron transport pathway in porphyrin, the electron transfer through oligomeric porphyrin molecular wires was studied in this work using first principle density function theory and non-equilibrium Green’s function calculations. The effects of chain length on the transportation behavior were discussed in terms of the electronic structures and transmission spectra. Through the analysis of spatial distribution of molecular frontier orbit we found that with the chain length increased, the whole delocalization of molecular frontier orbit enlarged, so e-transitivity became better. The results demonstrated that the frontier orbital energy gap decreased when the chain length increased, so that it should be conductive to electronic transmission. We presumed that the oligomeric porphyrin can be used to make moleculer electronic devices.

Abstract: The development situation and typical structure of color sorter were described in this paper. Based on the analysis of color sorter’s characteristic, the author proposed that color-sorting technique could use the color information of detecting materiel, not only limited to the optics characteristic of the materiel.

Abstract: Though gas quenching has several advantages, such as minimal environmental impact, little deformation, low energy cost, clean products, and ability to control the cooling locally and temporally for best product properties, its cooling performance is less than that of oil and water. If gas is mixed with spray water, the mixture will has favorable cooling performance. The cooling performance of eject quenching by mixture of Nitrogen-spray water is studied experimentally. Alloy steel 9SiCr is specimen, and it is quenched by a certain proportion of mixture gas of Nitrogen and spray water under normal pressure and high velocity, and the continual cooling curve is determined. The experimental results show that it can improve the cooling effect of quenching medium on the one hand; on the other hand, it can decrease the deformation and residual stress of specimen. The results also show that cooling performance of the mixture and cooling velocity can be enhanced by increasing gas pressure when the mixture ratio is fixed, and it takes short time to cool to room temperature. The cooling performance of the mixture and cooling velocity can be enhanced by increasing the mixture ratio under same pressure, and it also takes short time to cool to the room temperature. The continual cooling curve is determined, which gives the information of cooling performance of eject quenching by mixture of Nitrogen-spray water under Normal pressure changed with the pressure and the mixture ratio of Nitrogen and spray water.