3G手机的市场与发展趋势

一、引言 第三代移动通信主要是在传输声音和数据的速度上的提升，它能够处理图像、音乐、视频流等多种媒体形式，提供包括网页浏览、电话会议、电子商务等多种信息服务。     

Adsorption of boron from aqueous solutions using fly ash: batch and column studies

In the present paper, boron removal from aqueous solutions by adsorption was investigated. Fly ash particle size used in adsorption experiments was between 250 and 400 microm. During the experimental part of this study, the effect of parameters such as pH, agitation time, initial boron concentration, temperature, adsorbent dosage and foreign ion on boron removal were observed. In addition, adsorption kinetics, adsorption isotherm studies and column studies were made. Maximum boron removal was obtained at pH 2 and 25 degrees C. Thermodynamic parameters such as change in free energy (DeltaG degrees), enthalpy (DeltaH degrees), entropy (DeltaS degrees) were also determined. As a result of the kinetic studies, it was observed that the adsorption data conforms to the second degree kinetics model. In the isotherm studies, Langmuir and Freundlich isotherm models were applied and it was determined that the experimental data conformed to Langmuir isotherm model. Batch adsorbent capacity (q(o)) was calculated as 20.9 mg/g. The capacity value for column study was obtained by graphical integration as 46.2 mg/g. The Thomas and the Yoon-Nelson models were applied to experimental data to predict the breakthrough curves and to determine the characteristics parameters of the column useful for process design.     

Characterization of lactic acid bacteria isolated from Bukuljac, a homemade goat's milk cheese

The Bukuljac cheese is traditionally homemade cheese, produced from heat-treated goat's milk without the addition of any bacterial starter culture. The presence of lactic acid bacteria (LAB) in Bukuljac cheese has been analyzed by using a polyphasic approach including microbiological and molecular methods such as rep-PCR with (GTG)5 primer. Lactobacillus paracasei subsp. paracasei represents a dominant strain in the microflora of analyzed cheese. Out of 55 Gram-positive and catalase-negative isolates, 48 belonged to L. paracasei subsp. paracasei species. Besides lactobacilli, five Lactococcus lactis subsp. lactis and two Enterococcus faecalis were found. Results of PCR-denaturing gradient gel electrophoresis (DGGE) of DNA extracted directly from the fresh cheese revealed the presence of Leuconostoc mesenteroides. Only lactobacilli showed a high proteolytic activity and hydrolyzed alpha(s1)- and beta-caseins. They are also producers of diacetyl. In addition, 34 out of 55 isolates, all determined as lactobacilli, showed the ability of auto-aggregation. Among 55 isolates, 50 also exhibited antimicrobial activity.     

Sliding‐mode fault‐tolerant control using the control allocation scheme

This paper is devoted to the design of a novel fault‐tolerant control (FTC) using the combination of a robust sliding‐mode control (SMC) strategy and a control allocation (CA) algorithm, referred to as a CA‐based sliding‐mode FTC (SMFTC). The proposed SMFTC can also be considered a modular‐design control strategy. In this approach, first, a high‐level SMC, designed without detailed knowledge of systems' actuators/effectors, commands a vector of virtual control signals to meet the overall control objectives. Then, a CA algorithm distributes the virtual control efforts among the healthy actuators/effectors using the real‐time information obtained from a fault detection and reconstruction mechanism. As the underlying system is not assumed to have a rank‐deficient input matrix, the control allocator module is visible to the SMC module resulting in an uncertainty. Hence, the virtual control, in this scheme, is designed to be robust against uncertainties emanating from the visibility of the control allocator to the controller and imperfections in the estimated effectiveness gain. The proposed CA‐based SMFTC scheme is a unified FTC, which does not need to reconfigure the control system in the case of actuator fault or failure. Additionally, to cope with actuator saturation limits, a novel redistributed pseudoinverse‐based CA mechanism is proposed. The effectiveness of the proposed schemes is discussed with a numerical example.     

On the polymer modified cement mortars with different lightweight aggregates in marine environment

Having a light weight is a design objective for offshore and coastal structures and in order to reach this aim, use of lightweight concrete consisting lightweight aggregates and polymers is a feasible solution. In this study, materials obtained from locally available crushed volcanic scoria as main aggregate and some additional lightweight aggregates with ceramic, perlite and andesite as well polymers were used in the mixtures with different proportions (totally 14 mixtures) to propose feasible alternatives for coastal structure designers. To evaluate the design performances of the mixtures, their properties such as density, cylinder compressive strength, capillarity, loss of mass under the effects of the agents in marine environment such as sodium sulphate and sodium chloride were obtained experimentally. It was found that mixtures with scoria aggregates showed more favourable results and additional aggregates gave flexibility to the designer to lower densities up to 40 % ‐ 60 % of normal‐weight mixtures. Polymer modification also improved the performance of the related materials.     

Photoactive multi-walled carbon nanotubes: synthesis and utilization of benzoin functional MWCNTs

This study describes a facile method for the synthesis of functionalized multi-walled carbon nanotubes (MWCNTs) carrying photoactive group. The synthesis of MWCNTs-based macro-photoinitiator was achieved by the esterification reaction between benzoin moiety and acyl chloride functional MWCNTs. Synthesized MWCNT-based photoinitiator (MWCNTs–benzoin) was used in the photopolymerization of styrene to yield polystyrene (PS)-grafted MWCNTs (MWCNTs–PS) by “grafting from” method. The efficiency of MWCNTs–benzoin photoinitiator was determined by evaluating the effect of initiator to monomer ratio and reaction period on photopolymerization of styrene. Fourier transform infrared spectroscopy, Raman and X-ray photoelectron spectroscopy analyses confirmed the covalent bonding for functionalization of MWCNTs and determined the final structures. Thermogravimetric analysis, gel permeation chromatography and UV spectroscopy were performed to evaluate the grafting efficiency of PS that covalently grafted to MWCNTs, and high efficiency of MWCNTs–benzoin as a macro-photoinitiator was also confirmed. Scanning electron microscopy was used to determine the surface morphology of functionalized MWCNTs and MWCNTs–PS.     

一种USB测控应答机的健壮捕获算法

在统一S频段（USB）测控应答机中频数字化处理的基础上,提出了一种健壮的相位调制(PM)信号捕获算法。针对USB测控应答机输入信号存在副载波时捕获易于假锁的问题,采用快速傅里叶变换(FFT)与锁频锁相环结合的算法,利用PM信号频谱对称的特点,快速获得残差载波的正确频率,防止捕获到副载波信号或者其他干扰信号上;采用锁频锁相环实现PM信号的精确捕获与跟踪,适应USB测控应答机大动态多普勒变化及高灵敏度的要求。通过仿真试验验证了该方案载波正确捕获的有效性,且接收灵敏度达到-121 dBm。     

Spectroscopic and conductometric studies on the interactions of thionine with anionic and nonionic surfactants

In this study, the interaction of thionine, a cationic dye, with anionic [sodium dodecyl sulphate (SDS), lithium dodecyl sulphate (LiDS), and sodium dodecylbenzene sulphonate (SDBS)], nonionic (Tween 20 and Triton X‐100), and binary mixtures of anionic and nonionic surfactants was studied by conductometric and spectrophotometric measurements. The degree of ionisation, the counterion binding parameters, and the equilibrium constants in the premicellar region were obtained from conductivity data. Binding constants of thionine to anionic, nonionic, and mixtures of anionic and nonionic micelles were determined by spectrophotometric measurements. The binding tendency of thionine to anionic micelles followed the order SDBS > SDS > LiDS. The presence of nonionic surfactants increased significantly the binding affinity of thionine to anionic micelles, and the highest binding constant was calculated in the presence of Tween 20. The results obtained from conductometric studies correlated with those obtained from spectroscopic studies. Data concerning dye–surfactant interaction are important for a fundamental understanding of the performance of single and mixed surfactants and for their industrial application.     

Identification and control for heart rate regulation during treadmill exercise

This paper proposes a novel integrated approach for the identification and control of Hammerstein systems to achieve desired heart rate profile tracking performance for an automated treadmill system. For the identification of Hammerstein systems, the pseudorandom binary sequence input is employed to decouple the identification of dynamic linear part from input nonlinearity. The powerful epsilon-insensitivity support vector regression method is adopted to obtain sparse representations of the inverse of static nonlinearity in order to obtain an approximate linear model of the Hammerstein system. An Hinfinity controller is designed for the approximated linear model to achieve robust tracking performance. This new approach is successfully applied to the design of a computer-controlled treadmill system for the regulation of heart rate during treadmill exercise. Minimizing deviations of heart rate from a preset profile is achieved by controlling the speed of the treadmill. Both conventional proportional-integral-derivative (PID) control and the proposed approaches have been employed for the controller design. The proposed algorithm achieves much better heart rate tracking performance.     

采矿塌陷作用对地表生态环境的影响──以神木大柳塔矿区为研究区

野外实验研究表明，采矿塌陷作用不仅破坏包气带岩土结构，而且也改变包气带水分量状况和水势能状态；进而导致地表生态环境恶化，甚至出现土地沙化加剧的趋势。