三种科技文献半衰期算法的比较研究

文献半衰期是测度文献老化速度的一个重要指标,利用文献计量学和数理统计学的方法,对《工程力学》自1992年～2008年10月间的载文引文用三种半衰期的计算方法进行了计算,并且将结果和用插值法计算的结果进行了比较,计算结果表明：对《工程力学》而言,使用B-K方程计算的半衰期与插值法得到的结果最为接近。但是对超导专业期刊载文引文而言,新的半衰期计算公式得到的半衰期与插值法的结果最为接近。由此可见,在计算半衰期时,要选择最合适的公式进行计算。

力学文献老化速度50年(1954-2003)的变化趋势

运用文献计量学方法,对1954-2003年SCIE收录的106种力学专业期刊近20万篇文献文末所附的2 856 324条参考文献进行研究,考察了力学专业领域文献老化速度在50年间的变化趋势。用同时法计算了引文的半衰期和普赖斯指数后发现,50年来引文半衰期变得越来越长,相应地普赖斯指数越来越小。最大引文年限从50年前的2年变成目前的4年。研究结果表明,50年来力学专业文献的老化速度正在减慢。

引文半衰期与普赖斯指数之间的数量关系研究

本文运用文献计量学方法,对SCIE收录的106种力学专业期刊文献所附的2869099条参考文献进行了分析,考察了力学专业领域引文半衰期和普赖斯指数之间的关系,并用同时法计算了引文半衰期和普赖斯指数,将引文半衰期和普赖斯指数进行了比较。研究结果表明,引文半衰期和普赖斯指数成反比变化,引文半衰期和普赖斯指数之间存在着简单的数量关系:P(4)*H=2(P为普赖斯指数,H为引文半衰期)。通过普赖斯指数P(4)可以简便地近似计算引文半衰期,并具有较高的精度。

Joint eigenvalue estimation by balanced simultaneous Schur decomposition

The problem of joint eigenvalue estimation for the non-defective commuting set of matrices A is addressed. A procedure revealing the joint eigenstructure by simultaneous diagonalization of. A with simultaneous Schur decomposition （SSD） and balance procedure alternately is proposed for performance considerations and also for overcoming the convergence difficulties of previous methods based only on simultaneous Schur form and unitary transformations, it is shown that the SSD procedure can be well incorporated with the balancing algorithm in a pingpong manner, i. e., each optimizes a cost function and at the same time serves as an acceleration procedure for the other. Under mild assumptions, the convergence of the two cost functions alternately optimized, i. e., the norm of A and the norm of the left-lower part of A is proved. Numerical experiments are conducted in a multi-dimensional harmonic retrieval application and suggest that the presented method converges considerably faster than the methods based on only unitary transformation for matrices which are not near to normality.

Simultaneous Determination of Ceftazidime and Tazobactam in Injectable Powder by Reversed-Phase High Performance Liquid Chromatography

A reversed-phase high performance liquid chromatographic (RP-HPLC) method wasdeveloped and validated for the simultaneous deteimination of ceftazidime and tazobactam ininject-able powder. Methods Chromatography was carried out on Zorbax 300SB-C_(18) column using amixture of methanol and aqueous solution of phosphate buffer (pH = 5.6) as mobile phase. The UVdetection wavelength was 220 run. Results The linear ranges of ceftazidime and tazobactam were 0.62- 631.8 μg·mL^(-1) and 0.66 - 677.50 μg·mL^(-1), respectively. The average recoveries were 98.8%- 101.4% for ceftazidime, and 99,1% - 100.2% for tazobactam. The RSD values of inter-day andintra-day assays were lower than 1.5% for ceftazidime and 2.6% for tazobactam. Conclusion Thismethod is reproducible, simple, precise, and rapid for the quality control of ceftazidime andtazobactam in injectable powder.

Identification of Volatile Compounds in Codfish(Gadus) by a Combination of Two Extraction Methods Coupled with GC-MS Analysis

Codfish is a kind of abyssal fish species with a great value in food industry. However, the flavor of codfish, especially the unpleasant odor, has caused serious problems in its processing. To accurately identify the volatile compounds in codfish, a combination of solid phase micro-extraction(SPME) method and simultaneous distillation extraction(SDE) method was used to extract the volatiles. Gas chromatography-mass spectrometry(GC-MS) along with Kovats indices(KI) and authentic standard compounds were used to identify the volatiles. The results showed that a total of 86 volatile compounds were identified in codfish, of them 24 were extracted by SDE, 69 compounds by SPME, and 10 compounds by both SDE and SPME. Seventy volatile compounds were found to have specific odors, of them 7 typical compounds contributed significantly to the flavor of codfish. Alcohols(i.e.,(E)-2-penten-1-ol and 2-octanol), esters(i.e., ethyl butyrate and methyl geranate), aldehydes(i.e., 2-dodecenal and pentadecanal) contributed the most to fresh flavor while nitrogen compounds, sulphur compounds, furans, as well as some ketones(i.e., 2-hydroxy-3-pentanone) brought unpleasant odor, such as fishy and earthy odor. It was indicated that the combination of multiple extraction methods and GC-MS analysis can enhance the accuracy of identification, and provide a reference for the further study on flavor of aquatic products.

Research on the Bit Synchronization Algorithm and Multiplexing Technology in GNSS Receiver

In this paper, the bit synchronization algorithms in GNSS receiver are introduced, including the traditional histogram method, K-P algorithm and Viterbi algorithm. The FPGA implementation is also included. A novel time division multiplexing technology （TDM） based on multi-channel shared synchronizer is proposed in this paper to solve the constrained hardware resource problem of multi-system satellite navigation receiver. Through the using of control state machine and data register structure, we realize the multiplexing of bit synchronizer of navigation receiver, which saves the hardware resource. After the experiment, it can be verified that the receiver based on the bit synchronization and multiplexing technology can correctly restore the navigation information.

Simultaneous Determination of Saponins in Radix Glycyrrhizae, Notoginseng and Ginseng by High Performance Liquid Chromatography

To establish a method for determining five saponins(notoginsenoside R1, ginsenoside Rg1, ginsenoside Re, ginsenoside Rb1 and ammonium glycyrrhizinate) in Glycyrrhizae, Notoginseng and Ginseng, the high performance liquid chromatography with diode array detector(HPLC-DAD) method was applied to an Inertsil ODS-SP column(4.6 mm×250 mm, 5 μm) with a mobile phase consisting of acetonitrile-0.05% phosphoric acid in a gradient elution manner. The flow rate was 1.0 mL/min. The column temperature was 30 ℃ and the detection wavelengths were 203 nm and 237 nm, respectively. The linear ranges were 0.700,0—7.000,0 μg for R1(r=1.000,0), 0.751,1— 7.511,4 μg for Rg1(r=1.000,0), 0.677,2—6.771,6 μg for Re(r=1.000,0), 0.733,9—7.339,1 μg for Rb1(r= 1.000,0), and 0.540,0—5.399,8 μg for ammonium glycyrrhizinate(r=0.999,9), respectively. In addition, their average recoveries were 100.28%, 105.83%, 104.09%, 99.36% and 98.54%, respectively. The relative standard deviations(RSDs) of precision, reproducibility and recovery were all less than 1.5%. The results indicate that the method is simple, accurate and reproducible so that it can be used for the simultaneous determination of the five saponins in Chinese patent medicines containing the three kinds of herbs.

Knowledge mining collaborative DESVM correction method in short-term load forecasting

Short-term forecasting is a difficult problem because of the influence of non-linear factors and irregular events.A novel short-term forecasting method named TIK was proposed,in which ARMA forecasting model was used to consider the load time series trend forecasting,intelligence forecasting DESVR model was applied to estimate the non-linear influence,and knowledge mining methods were applied to correct the errors caused by irregular events.In order to prove the effectiveness of the proposed model,an application of the daily maximum load forecasting was evaluated.The experimental results show that the DESVR model improves the mean absolute percentage error(MAPE) from 2.82% to 2.55%,and the knowledge rules can improve the MAPE from 2.55% to 2.30%.Compared with the single ARMA forecasting method and ARMA combined SVR forecasting method,it can be proved that TIK method gains the best performance in short-term load forecasting.

Simultaneous separation and determination of four main isoflavonoids in Astragali Radix by an isocratic LC/ESI-MS method

A simple, reliable and rapid isocratic liquid chromatography(LC)-mass spectrometric detection(MS) coupled with electrospray ionization(ESI) method for simultaneous separation and determination of calycosin-7-O-β-D-glucoside, ononin, calycosin and formonometin in Astragali Radix was developed. After the samples were extracted with ethanol, the optimum separation conditions for these analytes were achieved using water and acetonitrile(70:30, v/v) containing 0.2%(v/v) acetic acid as a mobile phase and a 2.0 mm×150 mm Hypersil-Keystone C18 column. Selective ion monitoring(SIM) mode and [M+H]+ ions at m/z 447, 431, 285 and 269 were used for quantitative analysis of four main active components above mentioned. The calibration curves were linear in the range of 0.4-175.0 μg/mL for calycosin-7-O-β-D-glucoside, 0.2-146.0 μg/m L for ononin, 0.4-210.0 μg/mL for calycosin and 0.5-217.0 μg/mL for formonetion, respectively. The limits of quantification(LOQ) and detection(LOD) were 0.4 μg/mL and 0.08 μg/m L for calycosin-7-O-β-D-glucoside, 0.2 μg/mL and 0.06 μg/m L for ononin, 0.4 μg/mL and 0.1 μg/mL for calycosin, 0.5 μg/m L and 0.1 μg/m L formonetion, respectively. The standard recoveries were in the range of 96.5%-104.7%. The developed method has successfully been used for the determination of four main flavonoids in Astragali Radix from various sources and can be used for identification, differentiation and quality evaluation of Astragali Radix.

A new backtracking-based sparsity adaptive algorithm for distributed compressed sensing

A new iterative greedy algorithm based on the backtracking technique was proposed for distributed compressed sensing(DCS) problem. The algorithm applies two mechanisms for precise recovery soft thresholding and cutting. It can reconstruct several compressed signals simultaneously even without any prior information of the sparsity, which makes it a potential candidate for many practical applications, but the numbers of non-zero(significant) coefficients of signals are not available. Numerical experiments are conducted to demonstrate the validity and high performance of the proposed algorithm, as compared to other existing strong DCS algorithms.

Improved multi-objective artificial bee colony algorithm for optimal power flow problem

The artificial bee colony(ABC) algorithm is improved to construct a hybrid multi-objective ABC algorithm, called HMOABC, for resolving optimal power flow(OPF) problem by simultaneously optimizing three conflicting objectives of OPF, instead of transforming multi-objective functions into a single objective function. The main idea of HMOABC is to extend original ABC algorithm to multi-objective and cooperative mode by combining the Pareto dominance and divide-and-conquer approach. HMOABC is then used in the 30-bus IEEE test system for solving the OPF problem considering the cost, loss, and emission impacts. The simulation results show that the HMOABC is superior to other algorithms in terms of optimization accuracy and computation robustness.

Simultaneous (M,N) Singular Value Decomposition of Matrices

A necessary and sufficient condition for the existence of simultaneous (M,N)singular value decomposition of matrices is given.Some properties about the weighted partial ordering are discussed with the help of the decomposition.

On a Hybrid Preamble/Soft-Output Demapper Approach for Time Synchronization for IEEE 802.15.6 Narrowband WBAN

In this paper,we present a maximum likelihood(ML) based time synchronization algorithm for Wireless Body Area Networks(WBAN).The proposed technique takes advantage of soft information retrieved from the soft demapper for the time delay estimation.This algorithm has a low complexity and is adapted to the frame structure specified by the IEEE 802.15.6standard[1]for the narrowband systems.Simulation results have shown good performance which approach the theoretical mean square error limit bound represented by the Cramer Rao Bound(CRB).

Research on Preparation Method of Static Head Space for Volatile Organic Compounds in Drinking Water

[Objective] This research aimed to study the pre-treatment conditions of head space so as to establish a HS-GC determination method, which is suitable for China's conditions, for trace volatile organic compounds in drinking water. [Method]The preparation method of head space was adopted for the volatile organic compounds in drinking water. [Result] The 20 kinds of volatile organic compounds in drinking water all could be detected simultaneously by using HS-GC-FID method,and they all could be separated well. The HS-GC-FID method could analyze the detected substances qualitatively and quantitatively. In addition, this detection method was characterized by larger linear range of concentration, higher precision, higher detection limit and higher recovery rate. [Conclusion] Under certain conditions, HSGC can reduce the loss of volatile organic compound in drinking water and improve the sensitivity of detection. Moreover, the detection results meet the requirements by quality control.

Three Models of English Education in China＇s Universities ——-A Historical Perspective

In the present paper, a comparison is made of the three formats in the history of EECU （English education in China＇s universities）. In the first period （1904-1949）, English education was conducted separately in government-managed educational institutions and in institutions sponsored by church-related organizations; English education was well-knit with both general education and specialty education; and self-motivating learning was encouraged. In the second period （1950-1966）, almost everything was tinted with a shady color of politics： A halt was addressed drastically to EEC （English education in China） in 1952. In the gradual recovery that started four years later, the second format was sawed and hammered, showing the following features： All non-government-mamaged institutions vanished from the stage; English was taught solely as a language or a system of verbal parts, almost deprived of all cultural loading. The third period （1978 onwards） has witnessed a barrier-free and rapid development of over three decades, resulting in the unprecedented pervasion of EECU. Yet in the third tbrmat, learners＇ efforts have turned wholly test-oriented, degenerating into the saddening disintegrity of learning as a process into isolated charges to the target of a test at a time; the ignorant reduction of the learning methods to ＂Vocabulary Booklets Plus Collections of Test Papers＂. Such a comparison not only provides a multi-dimensional perspective of EECU and a better understanding of it, but also offers some important experiences and lessons for the search of an effective solution to the pervasive problem of＂Time-Consumingness and Low-Efficiency＂.

石榴皮色素的染色工艺

以石榴皮色素为研究对象,采用浸提染色同时法对毛织物进行染色,研究了石榴皮色素对毛织物、真丝、锦纶织物的染色工艺。试验结果表明:相比传统浸提染色分步法,浸提染色同时法能明显提高毛织物染色得色深度,并可简化从色素提取到染色成品之间的工序。

Simultaneous determination of brilliant blue and indigotine by derivative fluorescence spectrometry combined with WT-RBFNN

The mixed solutions of brilliant blue and indigotine are prepared and the fluorescence spectra of them are experimentally measured. The serious overlapping spectra of brilliant blue and indigotine are solved by means of the first-derivative fluorescence spectrometry. The wavelet coefficients, obtained by compressing the spectral data using wavelet transformation （WT）, are taken as inputs to establish the radial basis function neural network （RBFNN）. The neural network model can realize simultaneous determination of brilliant bFue and indigotine, and the mean relative errors of both compounds are 1.84% and 1.26%, respectively

HPLC-DAD data coupled with second-order calibration method applied to food analysis: Simultaneous determination of six benzoylurea insecticides in various fruit samples by selecting time region of chromatogram

This work presents a novel application of second-order calibration based on self-weighted alternating trilinear decomposition(SWATLD)algorithm for analyzing the HPLC-DAD data.The proposed method makes it possible to simultaneously determine teflubenzuron,hexaflumuron,flufenoxuron,chlorfluazuron,diflubenzuron and benzoylurea in different fruit samples,i.e.pear,apple and banana,in the selected time region of chromatogram.The concentration,elution time and spectral information of these benzoylurea insecticides are selectively extracted from complex matrices even in the presence of unknown interferences.The root-mean-square error of prediction(RMSEP)and figures of merit,including sensitivity(SEN),selectivity(SEL)and limit of detection(LOD)are employed to access the performance of the method.The LODs obtained for these insecticides are within the range 0.017–0.26 ppm in pears,0.039–0.33 ppm in apples,0.041–0.44 ppm in bananas,respectively.Such a chemometrics-based protocol holds great potential to be extended as a promising alternative for more practical applications in food safety and quality monitoring.

Time synchronization and ranging under unknown positions and velocities

The process to achieve time synchronization and ranging for a network of mobile nodes is raising a concern among researchers, and hence a variety of joint time synchronization and ranging algorithms have been proposed in recent years. However, few of them handle the case of all-node motion under unknown positions and velocities. This study addresses the problem of determining ranging and time synchronization for a group of nodes moving within a local area. First, we examined several models of clock discrepancy and synchronous two-way ranging. Based upon these models, we present a solution for time synchronization with known positions and velocities. Next, we propose a functional model that jointly estimates the clock skew, clock offset, and time of flight in the absence of a priori knowledge for a pair of mobile nodes. Then, we extend this model to a network-wide time synchronization scheme by way of a global least square estimator. We also discuss the advantages and disadvantages of our model compared to the existing algorithms, and we provide some applicable scenarios as well. Finally, we show that the simulation results verify the validity of our analysis.