Dynamic feedback control for cycle slipping in a phase-controlled system

This paper concerns the problem of cycle slipping for continuous phase-controlled systems with periodic nonlinearity. The number of slipped cycles is an important property in the transient mode of such nonlinear systems. On the basis of the Yakubovich–Kalman lemma, linear matrix inequality (LMI) characterizations are derived for the number of slipped cycles of such systems and an efficient way of estimating the number is proposed by solving a generalized eigenvalue minimization problem. Furthermore, by virtue of these results, a dynamic output feedback controller is designed to guarantee the nonexistence of cycle slipping. As a result, the transient performance of phase-controlled system is improved. A concrete application to the phase-locked loop shows the applicability and validity of the proposed approach.     

Spectroscopic studies on interaction and sonodynamic damage of metallochlorophyllin (Chl-M (M=Fe, Zn and Cu)) to protein under ultrasonic irradiation

In this paper, the chlorophyll derivatives, metallochlorophyllin (Chl-M) (M=Fe, Zn and Cu) including chlorophyllin iron (Chl-Fe), chlorophyllin zinc (Chl-Zn) and chlorophyllin copper (Chl-Cu), were adopted as sonosensitizers to combine with ultrasonic irradiation, and the sonodynamic damage of bovine serum albumin (BSA) was investigated. At first, the interaction of Chl-M with BSA was studied by fluorescence spectroscopy. The results show that the quenching mechanism belongs to a static process and among them the affinity of Chl-Fe to BSA is the most obvious. Then, some influence factors on the sonodynamic damage of BSA molecules in the presence of Chl-M under ultrasonic irradiation were also studied. Synchronous fluorescence spectra show that the binding and damage sites of Chl-M to BSA molecule are mainly on the tryptophan (Trp) residues. The generation of ROS in Chl-M sonodynamic process is estimated by the method of Oxidation-Extraction Spectrometry (OEP). This paper may offer some valuable references for the study of the sonodynamic activity of Chl-M and the effect of the central metals. Synchronously, it contributes to the application of Chl-M in SDT for tumor treatment.     

The investigation of sonocatalytic activity of Er3+:YAlO3/TiO2-ZnO composite in azo dyes degradation

In this work, the emphasis was mainly placed on investigating the sonocatalytic activity of TiO(2)-ZnO mixed with Er(3+):YAlO(3), namely, Er(3+):YAlO(3)/TiO(2)-ZnO composite. It is able to utilize the sonoluminescence light to improve the sonocatalytic degradation of organic dyes. The Er(3+):YAlO(3) as up-conversion luminescence agent was synthesized by sol-gel and auto-combustion method, and then Er(3+):YAlO(3)/TiO(2)-ZnO composite as sonocatalyst were prepared by ultrasonic dispersion and liquids boil method. The prepared up-conversion luminescence agent and composites were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Acid Red B dye was selected to examine the sonocatalytic activity of Er(3+):YAlO(3)/TiO(2)-ZnO composite. The degradation reaction processes were monitored by UV-vis spectrophotometer and ion chromatogram. The influences on the activity of the Er(3+):YAlO(3)/TiO(2)-ZnO such as Ti/Zn molar ratio, heat-treated temperature and heat-treated time were studied. The results showed that the Er(3+):YAlO(3)/TiO(2)-ZnO composite exhibited a significantly high sonocatalytic activity compared with other catalysts in the degradation of Acid Red B. And the sonocatalyst with 1:1 Ti/Zn molar ratio heat-treated at 550°C for 60min showed the highest sonocatalytic activity. At last, the experiment also indicated that it has a good sonocatalytic activity to degrade other organic dyes.     

Sobolev方程的一类各向异性非协调有限元逼近

在各向异性网格下,分别讨论了Sobolev方程在半离散和全离散格式下的一类非协调有限元逼近,得到了与传统有限元方法相同的误差估计和一些超逼近性质.同时在半离散格式下,通过构造具有各向异性特征的插值后处理算子得到了整体超收敛结果.     

Pyrolysis of polyester and viscose fiber over ZSM-5: synergistic effect and distribution of products

Journal of Thermal Analysis and Calorimetry - Large amounts of textile wastes are discarded annually, not only polluting the environment but also causing a significant waste of resources. Here, we...     

Protein separation using free‐flow electrophoresis microchip etched in a single step

A one‐step etching method was developed to fabricate glass free‐flow electrophoresis microchips with a rectangle separation microchamber (42 mm‐long, 23 mm‐wide and 28 μm‐deep), in which two glass bridges (0.5 mm‐wide) were made simultaneously to prevent bubbles formed by electrolysis near the Pt electrode from entering the separation chamber. By microchip free‐flow zone electrophoresis, with 200 V voltage applied, the baseline separation of three FITC labeled proteins, ribonuclease B, myoglobin and β‐lactoglobulin, was achieved, with resolution over 1.78. Furthermore, with 2.5 mM Na₂SO₄ added into the electrode buffer to form higher electrical field strength across separation microchamber than electrode compartments, similar resolution of samples was achieved with the applied voltage decreased to 75 V, which could obviously decrease Joule heat during continuous separation. All these results demonstrate that the free‐flow electrophoresis microchip fabricated by one‐step etching method is suitable for the continuous separation of proteins, which might become an effective pre‐fractionation method for proteome study.     

Sonocatalytic degradation of some dyestuffs and comparison of catalytic activities of nano-sized TiO2, nano-sized ZnO and composite TiO2/ZnO powders under ultrasonic irradiation

Here, a novel sonocatalyst, composite TiO2/ZnO powder, was prepared through the combination of nano-sized TiO2 and ZnO powders. Because of the appropriate adsorbability to organic pollutants and special crystal interphase between TiO2 and ZnO particles, the composite TiO2/ZnO powder exhibits a high sonocatalytic activity under ultrasonic irradiation during the degradation of acid red B. Especially, the sonocatalytic activity of composite TiO2/ZnO powder with 4:1 molar proportion treated at 500 degrees C for 50 min showed obvious improvement compared with pure nano-sized TiO2 and ZnO powders. When the experimental conditions such as 10mg/L acid red B concentration, 1.0 g/L catalyst addition amount, pH=7.0, 20 degrees C system temperature, 100 min ultrasonic time and 50 mL total volume were adopted, the satisfactory degradation ratio and rate were obtained. All experiments indicate that the sonocatalytic method using composite TiO2/ZnO powder may be a more advisable choice for the treatments of non- or low-transparent organic wastewaters in future.     

Morley type non‐C0 nonconforming rectangular plate finite elements on anisotropic meshes

In this article, two Morley type non‐C⁰ nonconforming rectangular finite elements are discussed to numerically solve the fourth order plate bending problem under anisotropic meshes. The optimal anisotropic interpolation error and consistency error estimates are obtained by using some novel approaches. Some numerical tests are given to confirm the theoretical analysis. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2010     

Sonocatalytic degradation of methyl parathion in the presence of nanometer and ordinary anatase titanium dioxide catalysts and comparison of their sonocatalytic abilities

The degradation of methyl parathion (O,O-dimethyl-O-(4-nitrophenyl)-phosphorothioate) using anatase titanium dioxide (TiO₂) powder as heterogeneous sonocatalysts is reported. The influences of reaction parameters such as the species of TiO₂ sonocatalysts, methyl parathion concentrations, TiO₂ adding amount, pH, ultrasonic intensity, ultrasonic frequency and temperature have been investigated and the optimal conditions for eliminating methyl parathion have been identified. The efficiencies of sonocatalytic degradation in both nanometer and ordinary anatase systems are compared and the results indicate that the sonocatalytic activity of nanometer anatase TiO₂ powder is better than that of ordinary anatase TiO₂ powder. The primary degradation and the total mineralization of methyl parathion have been monitored by high performance liquid chromatography (HPLC) and UV–vis spectra, respectively. Methyl parathion got destroyed to some extent in both nanometer and ordinary anatase systems under ultrasonic irradiation. The kinetics for the degradation process of methyl parathion follows the first-order reaction. The degradation ratio of methyl parathion surpassed 90% within 50 min in the optimal experiment conditions.