最新电影

《尖峰时刻3》；《谍影重重3》；《星尘》；《1408幻影空间》；《入侵》；《变形金刚》；《导火线》；《医疗内幕》；     

新片

《战争之王》；《黑客帝国》；《迷失东京》；《忠奸人》；《魔界契约》；《加勒比海盗：聚魂棺》；《蝎子王》     

高清片源

《阿波罗13号》；《300》；《Blue Planet》；《Bridge to Terabithia》；《黑客帝国I》；《Ghost Rider》；我们曾是战士；     

声色季

《凶兆》；《启示》；《篱笆墙外》；《超人归来》；《魔鬼穿着普拉达》；《暴力城》；《加菲猫：两只猫的故事》；《无赖教师》。     

新碟报

《变形金刚》电影版；《蜘蛛侠3》；《狩猎季节》；《国王班底》；《夜宴》；《宝贝计划》。     

新电影

《加勒比海盗3》；《怪物史莱克3》；《蜘蛛侠3》；《刑房》：血腥的玩笑；《乔治亚法则》；《后窗惊魂》：跟大师学点皮毛；《初雪之恋》；《冰刀双人组》；     

New Movies

《空中蛇患》；《不可征服》；《方糖》；《时间》；《龙虎门》；     

生财有道

《赤龙剑心》；《飞飞》；《梦幻西游》；《魔力宝贝》；     

先睹为快

《幽灵骑士》；《电灯泡》；《德州链锯杀人狂前传》；《加勒比海盗2：亡灵的宝藏》；《迈阿密风云》；[编者按]     

新书上架

《道不远人》；《CSS实战手册》；《Struts2权威指南》；《敏捷估计与规划》；《搜索引擎优化》。     

Supervised adaptive clustering: A hybrid neural network clustering algorithm

A neural network architecture is introduced which implements a supervised clustering algorithm for the classification of feature vectors. The network is selforganising, and is able to adapt to the shape of the underlying pattern distribution as well as detect novel input vectors during training. It is also capable of determining the relative importance of the feature components for classification. The architecture is a hybrid of supervised and unsupervised networks, and combines the strengths of three wellknown architectures: learning vector quantisation, backpro-pagation and adaptive resonance theory. Network performance is compared to that of learning vector quantisation, back-propagation and cascade-correlation. It is found that performance is generally as good as or better than the performance of these other architectures, while training time is considerably shorter. However, the main advantage of the hybrid architecture is its ability to gain insight into the feature pattern space.Nomenclature O _j The output value of thejth unit - I _i Theith component of the input pattern - W _ij The weight of the cluster connection between theith input and thejth unit - B _ij The weight of the shape connection between theith input and thejth unit - N The dimension of the input patterns - v _j The vigilance parameter of thejth unit - v _init The initial vigilance parameter value - v _rate The change in the vigilance parameter value - X _i Theith direction in anN-dimensional coordinate system - T _k The classification tag of thekth unit - C The classification tag of the current input vector - (p) The learning rate at thepth epoch for the cluster weights - p The current epoch - P The total number of epochs - E _k The error associated with thekth unit - The constant learning rate for the shape weights - a _j The age in epochs of thejth unit     

The photoionization of excited hydrogen atom in plasmas

The photoionization processes of excited hydrogen atoms in plasma environments are investigated using the method of complex coordinate rotation. The standard Debye–Hückel model and modified Debye–Hückel model are adopted to describe the plasma screening effects. The photoionization cross sections of plasma-embedded excited hydrogen atoms varied with different screening lengths are displayed to illustrate the influence of plasma screening. The results of the Debye–Hückel model compared with the modified Debye–Hückel are presented. The shape resonances and Cooper minima due to the plasma screening are observed and discussed.     

Correlations of the impedance parameters and conductivity and permittivity of liquid and gel phases in a series piezoelectric quartz crystal sensor

The impedance characteristics of a series piezoelectric quartz crystal (SPQC) sensor were investigated using a network/impedance analyzer. The correlations between the impedance parameters, including the magnitude and phase of the impedance and the resonant frequencies, and the conductivity and/or the permittivity of the test solutions were derived theoretically and in good agreement with the experimental results. It was shown that the value of the series frequency (f_s) decreases with increasing conductivity and permittivity of the liquid. The parallel frequency (f_p) is the constant. The values of the maximum impedance (|Z|_max) and corresponding frequency (f_max,), are not related to the conductivity and permittivity of the liquid. The value of the minimum impedance (|Z|_min) decreases with increasing permittivity and has a maximum in a solution of middle conductivity. The corresponding frequency (f_min) has the same value as the f_s. The maximum phase of the impedance (θ_max) increases slightly with increasing permittivity and has a minimum in electrolyte solution of middle conductivity. In the impedance–frequency curves, there is an iso-impedance point for the SPQC in electrolyte solutions. The SPQC method was applied to monitor the process of hydrogel formation.     

Simultaneous kinetic spectrophotometric determination of sulfide and sulfite ions by using an optode and the partial least squares (PLS) regression

The characterization of an optical sensor membrane is described for simultaneous determination of sulfite and sulfide ions based on the immobilization of crystal violet on a triacetylcellulose membrane. The absorbance of the membranes decreased by increasing sulfite and sulfide concentration. The partial least squares (PLS-1) calibration model based on spectrophotometric measurement for simultaneous determination of sulfite and sulfide ions was applied. This method is based on the difference between the rate of the reaction of sulfide and sulfite with membranes in pH 7.0 buffer solution and at 25 °C. The experimental calibration matrix for partial least squares (PLS-1) calibration was designed with 18 samples. The cross-validation method was used for selecting the number of factors. The results showed that simultaneous determination could be performed in the range of 200–2000 μg mL⁻¹ (2.5–25 mmol L⁻¹) and 80–900 μg mL⁻¹ (2.5–28.125 mmol L⁻¹) for sulfite and sulfide, respectively. The sensor can readily be regenerated with water and the color is fully reversible. The sensor was successfully applied to the simultaneous determination of sulfide and sulfite in water samples.     

Wideband bandpass filtering branch‐line balun with high‐isolation

The wideband bandpass filtering branch‐line balun with high isolation is presented in this paper. The proposed balun can be designed for wideband performances by choosing a proper characteristics impedance of input vertical transmission line and odd‐mode impedance of parallel‐coupled lines. The proposed balun was designed at a center frequency (f₀) of 3.5 GHz for validation. The measured results are in good agreement with the simulations. The measured power divisions are ?3.31 dB and ?3.24 dB at f₀ and ?3 ± 0.17 dB within the bandwidth of 0.95 GHz (3 GHz to 3.95 GHz). The input return loss of 24.09 is measured at f₀ and higher than 20 dB over the same bandwidth. Moreover, the measured output losses are better than 11 dB within a wide bandwidth. The isolation between output ports is 20.32 dB at f₀ and higher than 13.2 dB for a broad bandwidth from 1 GHz to 10 GHz. The phase difference and magnitude imbalance between two output ports are 180° ± 4.5° and ± 0.95 dB, respectively, for the bandwidth of 0.95 GHz.     

A 5 GHz LC-VCO frequency synthesizer for unlicensed band of WiMAX

This paper presents a low power and low phase noise CMOS integer-N frequency synthesizer based on the charge-pump Phase Locked Loop (PLL) topology. The frequency synthesizer can be used for IEEE 802.16 unlicensed band of WiMAX (World Interoperability for Microwave Access). The operation frequency of the proposed design is ranged from 5.13 to 5.22 GHz. The proposed Voltage-Controlled Oscillator (VCO) achieves low power consumption and low phase noise. The high speed divider is implemented by an optimal extended true single phase clock (E-TSPC) prescaler. It can achieve higher operating frequency and lower power consumption. A new frequency divider is also proposed to eliminate the hardware overhead of the S counter in the conventional programmable divider. The proposed frequency synthesizer consists of a phase-frequency detector (PFD), a charge pump, a low-pass loop filter, a VCO, and a frequency divider. The simulated phase noise of the proposed VCO is −121.6 dBc/Hz at 1 MHz offset from the carrier frequency. The proposed frequency synthesizer consumes 13.1 mW. The chip with an area of 1.048 × 1.076 mm² is fabricated in a TSMC 0.18 μm CMOS 1P6M technology process.     

WO3 nanocrystals: Synthesis and application in highly sensitive detection of acetone

WO₃ nanocrystals have been prepared by a sol-gel route and characterized by X-ray diffractometry, scanning electron microscopy, and transmission electron microscopy. The experimental results show that WO₃ nanocrystals have a high crystallographic quality and a good dispersivity. The particles’ sizes are in the range of 25-100 nm. The fabricated WO₃ nanocrystal-based sensors have an excellent sensitivity and selectivity to acetone, and display a rapid response and recovery characteristics. The developed sensors exhibit a detection limit down to 0.05 ppm at 300 °C, rendering a promising application in noninvasive diagnosis of diabetes. The response mechanism of the WO₃ nanocrystal sensor to low concentration of acetone has been discussed based on the depletion layer model.     

SBGBBG, a program to evaluate the macroscopic strain/stress tensor of a polycrystalline sample from X-ray reflection positions

The evaluation of the strain/stress tensor from strain measured by X-ray diffraction requires a transformation from the sample system S to the laboratory system L. The transformation matrix A depends on the diffractometer geometry and the sample tilting. The conversion from strain to stress relies on poly-crystal elastic compliances S′_mnop. The averaging is done about the orientation of the diffracting crystallites. The orientation distribution function (ODF) serves as weighting function. The computer program SBGBBG carries out these calculations.     

Amperometric biosensor for catechol using electrochemical template process

A novel amperometric biosensor for the determination of catechol was developed accordingly to the electrochemical template procedure. The optimum fabricating conditions of the biosensor were studied. The resulting biosensor with the limit of less than 0.05 μM can be used for detection of catechol in the linear range of 2.5-140 μM. The maximum response current (I_max) and the Michaelis-Menten constant (k′_m) are 3.08 μA and 77.52 μM, respectively. The activation energy (E_a) of the polyphenol oxidase (PPO) catalytic reaction is 25.56 kJ mol⁻¹ in the B-R buffer. The stability of the PANI-CA biosensor fabricated with the electrochemical template process (retains 86% of the original activity after four months) is much higher than that fabricated with one-step and two-step processes (retains 75% of the original activity after four months). The effects of potential and pH on the response current of the biosensor are also described.     

Modeling of thermodynamic properties of ABr-PrBr3 (A=Li-Cs ) systems

The thermodynamic properties of ABr-PrBr₃(A=Li-Cs) systems were assessed by the CALPHAD method. The liquid phase in the systems was described by the non-stoichiometric associate model. The entropies of mixing in the liquid were evaluated from experimental liquidus and enthalpy of mixing data. For the pseudobinary compounds A₃PrBr₆,APr₂Br₇, and A₂PrBr₅ (A=K,Rb) and Cs₃PrBr₆ and CsPr₂Br₇, the dependences of Gibbs energies of formation on temperature were calculated. The anomalies of sequences of thermodynamic properties in RbBr-PrBr₃ were observed and discussed. The nature of the liquid phase and precision of calculations of the Rb₂PrBr₅(s) compound were discussed.