Tracking Control and Synchronization for Two-Dimension Discrete Chaotic Systems

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跟踪系统中跟踪器延迟的自适应预测补偿方法

跟踪系统中跟踪器的延迟会对系统的稳定性和跟踪精度产生不利影响。为此以典型Ⅱ型系统为例，理论上定理地分析了跟踪器延迟对跟踪系统的影响，并提出了将采用LMS算法和横向滤波器结构的自适应滤波器用于延迟预测补偿的方法。仿真结果验证了方法的有效性。     

The Effect of the Charge Fluctuation of Dust Parti-cles on Ion-acoustic Wave Excited Through Ionization Instability

The effect of the charge fluctuation of dust particles on ion acoustic wave (IAW) excited through ionization instability was investigated. The hydrodynamic equations and linear time-dependent perturbation theory served as the starting point of theory, by which the dispersion relation and growth rate of the IAW were given. By comparing the results with the case of constant dust charges, it was found that the charge fluctuation of dust particles reduces the instability of the wave mode.     

具有再生反馈雷达的角跟踪性能闭环测试

本文论述了用雷达跟踪目标最大角速度和角加速表征具有再生反馈雷达角跟踪性能的合理性,并论述了用单片机测试雷达跟踪目标最大角速度和最大角加速的方法。     

高透明耐冲击聚氯乙烯接枝聚合研究

研究高透明耐冲击聚氯乙烯接枝聚合工艺，讨论了加料顺序、复合分散体系以及采用聚集粒子乳液、并用碱性物质调节其ｐＨ值等对接枝聚合物性能的影响，确定了接枝聚合最佳工艺条件。     

Direct preparation of particles from liquid suspension for ESEM or SEM analysis

A simplified method for the preparation of particles from liquid suspensions has been developed. Particles are deposited directly on carbon planchets for rapid analysis by environmental scanning electron microscopy or by conventional scanning electron microscopy after an additional drying step. This is accomplished by filtering the liquid through thin carbon planchets. Three different grades of graphite were investigated for their suitability as the source material for these planchets. The high quality isomolded graphite is recommended for the filtration and direct observation of particles by electron microscopy. This technique is demonstrated for particles in hydraulic fluid and aquatic suspended particulate material from a natural water source.     

A polydispersed particle system representation of the porosity for non-saturated cementitious materials

In this paper, the porosity of cementitious materials is described in terms of pore size distribution by means of a 3-dimensional overlapping sphere system with polydispersivity in size. On the basis of results established by Lu and Torquato [B. Lu, S. Torquato, Nearest-surface distribution functions for polydispersed particle systems, Phys. Rev. A 45(8) (1992) 5530-5544] and Torquato [S. Torquato, Random Heterogeneous Media: Microstructure and Macroscopic Properties. Springer-Verlag: New York, 2001] providing relations for nearest-neighbor distribution functions, the volume fraction of pores having a radius larger than a prescribed value is explicitly expressed. By adopting an appropriate size distribution function for the sphere system, it is shown that the pore size distribution of cementitious materials as detected for instance by mercury intrusion porosimetry (MIP), which generally points out several pore classes, can be well approached. On the basis of this porosity representation, the evaluation of the capillary pressure in function of the saturation degree is provided. The model is then applied to the simulation of the saturation degree versus relative humidity adsorption curves. The impact of the pore size distribution, the temperature and the thickness of the adsorbed water layer on these parameters are assessed and analyzed for three model materials having different pore characteristics.     

Feasibility study on the use of polyallyldiglycol-carbonate cell dishes in TUNEL assay for alpha particle radiobiological experiments

In the present work, we have studied the feasibility of a method based on polyallyldiglycol-carbonate (PADC) films to investigate the effects of alpha particles on HeLa cervix cancer cells. Thin PADC films with thickness of about 20 μm were prepared from commercially available CR-39 films by chemical etching to fabricate custom-made petri dishes for cell culture, which could accurately record alpha particle hit positions. A special method involving “base tracks” for aligning the images of cell nuclei and alpha particle hits has been proposed, so that alpha particle transversals of cell nuclei can be visually counted. Radiobiological experiments were carried out to induce DNA damages, with the TdT-mediated dUTP Nick-End Labeling (TUNEL) fluorescence method employed to detect DNA strand breaks. The staining results were investigated by flow cytometer. The preliminary results showed that more strand breaks occurred in cells hit by alpha particles with lower energies. Moreover, large TUNEL positive signals were obtained even with small percentages of cells irradiated and TUNEL signals were also obtained from non-targeted cells. These provided evidence for the bystander effect.     

Solid State Concepts to Understand Catalysis Using Nanoscale Metallic Particles

New advances in theoretical background and recent experimental results concerning nanometer scale metallic clusters are presented. We will begin by a presentation of the advantages and the limitations of synchrotron radiation techniques to characterise nanometer scale entities. Then, through a review of recent papers, we try to make a link between metallic surfaces and nanometer scale monometallic clusters in the case of the interaction with a small molecule, namely NO.     

Theoretical Investigation of Time Suboptimal Control of Industrial Manipulators Along Specified Paths

A method for the time suboptimal control of an industrial manipulator from an initial position and orientation to a final position and orientation as it moves along a specified path is proposed. Nonlinear system equations that describe the manipulator motion are linearized at each time step along the path. A method which gives the control inputs (joint angular velocities) for time suboptimal control of the manipulator is developed. In the formulation, joint angular velocity and acceleration limitations are also taken into consideration. A six degree of freedom elbow type manipulator is used in numerical examples to verify the method developed.