Neural-network-based classification of Space Acceleration Measurement Systems (SAMS) data via supervised learning

This paper illustrates the applicability of neural networks in classifying events using Space Acceleration Measurement System (SAMS) data. Computer programs have been written in the MATLAB environment for the following purposes: automatic retrieval of SAMS data from NASA CDROM disks, computation of power spectral densities for SAMS data and construction of input patterns for the training of a multi-layer neural network (MNN). The MNN has been trained using the backpropagation learning algorithm and the SAMS data collected on the STS-50 Space Shuttle mission for three crew exercise events. It is found that the trained MNN is highly successful in classifying events. In addition, the performance of MNN is found to be better than that of the nearest neighbor classifier.     

基于加速度传感器测量扭振方法的研究

介绍一种把加速度传感器直接安装在转子上,在旋转坐标系下测量转子扭振的测量方法.简述其实现原理,设计利用单盘转子产生扭振的实验装置,并进行实验.实验结果与位移传感器测量结果进行比较,表明该方法可以测量小幅值的扭转振动,且具有较高的精度.在旋转状态下进行齿轮实验装置的测试,同样得到与已知故障特征一致的扭振信号.     

Unsupervised and supervised classification of AE data collected during fatigue test on CMC at high temperature

This paper aims at giving a better understanding of damage mechanisms that control lifetime of C_f/SiC composites at high temperatures (700-1200 °C) under static and cyclic fatigue. Acoustic emission (AE) signals were analysed with a view to identify classes corresponding to a specific damage mode. An unsupervised classification method allowed differentiating signals resulting from the following damage mechanisms: collective or individual fibre breaks, matrix cracking, fibre/matrix debonding, yarn/yarn debonding and sliding at fibre/matrix interfaces or matrix cracks closing after unloading. Then, a supervised classification method was developed. It allows real-time identification of damage mechanisms regardless of testing conditions (temperature, applied load and loading mode).     

烟气排放污染物(SO2)在线监测系统

紫外 可见差分吸收光谱法 (DOAS)是一种可用于在线式烟气排放污染物自动监测的新型方法 ,它在不改变被测试样成分的前提下 ,可以同时对多种气体进行连续测量。对获得的吸收光谱数据由计算机处理 ,可实时记录烟气中各种污染物的含量 ,并对未知成分的气体进行判断。介绍了基于这种测量方法的测试系统的结构、工作原理 ,并利用所建立的测试系统进行了实验研究。测试结果表明 :采用差分吸收光谱法所测得的SO2 浓度在满量程范围内偏差均≤± 1 5 % ,完全可以满足烟气排放污染物 (SO2 )连续在线监测的要求     

Improvement of classification using robust soft classification rules for near-infrared reflectance spectral data

The aim of this work was to propose a quick and cost-effective procedure, which could help to identify the types of fat (rapeseed, a mixture of rapeseed and soybean, and lard oils) added to feed used for raising pigs. For this purpose, liver samples were examined and their near-infrared reflectance spectra served as data for the construction of classic and robust soft independent modeling of class analogy (SIMCA) models. The results showed that the near-infrared reflectance spectra contained information sufficient to build good classification models that enabled three types of fat additions to be distinguished. The best classification results were obtained from robust SIMCA, indicating its superior performance in terms of high sensitivity and specificity in comparison with classic SIMCA. Specifically, robust models had sensitivities of 100% and specificities of 96.05%, 97.73% and 100%, for rapeseed, mixture of rapeseed and soybean, and lard enriched feed, respectively.     

Pb_2Bi_(0.2)Nb_2O_(7.3)—一种具有烧录石型层状超结构的新化合物

首次制备了 Pb_2Bi_(0.2)Nb_2O_(7.3),一种具有烧录石型层状超结构的新化合物。摄得的 X 射线劳埃、回摆及 Weiss-enberg 照相表明该单晶属三方晶系,劳埃群(?)m。晶胞参数为 a=7.467(1)(?),c=66.14(1)(?)。     

Photolytic decolorization of Rose Bengal by UV/H(2)O(2) and data optimization using response surface method

Rose Bengal (C.I. name is Acid Red 94) was irradiated with UV light in the presence of hydrogen peroxide. The photoinduced decolorization of the dye was monitored spectrophotometrically. The apparent rate of decolorization was calculated from the observed absorption data and was found to be pseudo first order. A systematic study of the effect of dye concentration and H(2)O(2) concentration on the kinetics of dye decolorization was also carried out. Dye decolorization increased with increasing H(2)O(2) concentration and decreasing dye concentration. The maximum dye decolorization was determined as 90% with 0.005 mM dye at optimum 0.042 M H(2)O(2) and pH 6.6. Additionally, the effect on decolorization of this dye in the presence of some additives (ions) was also investigated. It was seen that sulphite caused a maximum effect on % decolorization of the dye solution. A plausible explanation involving the probable radical initiated mechanism was given to explain the dye decolorization. The experimental data was also optimized using the response surface methodology (RSM). According to ANOVA results, the proposed model can be used to navigate the design space. It was found that the response of Rose Bengal degradation is very sensitive to the independent factors of dye concentration, H(2)O(2) concentration, pH and reaction time. The proposed model for D-optimal design fitted very well with the experimental data with R(2) and R(adj)(2) correlation coefficients of 0.85 and 0.80, respectively.     

Measurement of interfacial fracture parameters using coherent gradient sensing (CGS)

An optical interferometry called coherent gradient sensing (CGS) has been extended for mapping interface crack tip fields and for evaluating fracture parameters. The optical technique is a double grating shearing interferometer with an on line spatial filtering arrangement. The method offers real time full field measurements and can be used both in transmission made and reflection mode. The interferometer measures small angular deflections of light rays which can be further related to in plane gradients of _x + _y in transmission through elasto-optic relations. Direct interfacial crack tip measurements in a high stiffness mismatch PMMA-aluminium bimaterial system are performed. A variety of crack tip mode mixities are studied using asymmetric four point bend specimens subjected to different far field mechanical loads. The. complex stress intensity factors and the associated phase angles are measured from CGS patterns using an asymptotic expansion field. The measurements are compared with finite element results.     

测量系统分析在曲轴测量机上的应用

本文介绍测量系统分析的一般概念,探讨、研究曲轴测量机这一测量系统所涉及的偏倚、线性、稳定性、重复性等一系列问题,提出在实际生产现场评定曲轴测量机的方法。     

Measurement of the Refractive Indices of H(2)SO(4)-HNO(3)-H(2)O Solutions to Stratospheric Temperatures

Refractive indices of various H(2)SO(4)-H(2)O, HNO(3)-H(2)O, and H(2)SO(4)-HNO(3)-H(2)O solutions were measured at four wavelengths in the visible (351.0, 533.5, 632.9, and 782.6 nm) over a temperature range from 30 to -60 degrees C. The temperature dependence has been determined for the first time to the authors' knowledge. This dependence is of importance for applications to atmospheric aerosols at low temperatures. In particular, it is shown that (1) the molar refractivity of the solutions is independent of temperature, whereas the temperature dependence of the refractive index arises solely through the temperature dependence of the solution's mass density, (2) the molar refractivities of H(2)SO(4) and HNO(3) in a ternary solution may be calculated as the weighted sum of the molar refractivities of two binary solutions evaluated at a concentration that corresponds to the total acid concentration, and (3) the H(2)O molar refractivity in the solutions may be taken equal to that of pure water. Although the data for the ternary system have been used for this model verification, data for binary H(2)SO(4)-H(2)O and HNO(3)-H(2)O solutions were used to improve the accuracy of the modeled refractive indices to better than 0.0017% or 0.15% for concentrations of 5-70 wt.% and wavelengths from the near ultraviolet to the near infrared (0.25-2 mum).     

Decolourization of Methyl Orange using Fenton-like mesoporous Fe(2)O(3)-SiO(2) composite

Rapid decolourization of Methyl Orange by Fenton-like mesoporous Fe(2)O(3)-SiO(2) catalyst has been reported. The effect of various parameters such as initial pH, initial H(2)O(2) concentration, Fe content in the catalyst and initial dye concentration on decolourization process were studied. The results show that 20mg of mesoporous Fe(2)O(3)/SiO(2) composite (with Si/Fe=10) was sufficient to decolourize 0.6 mg/ml of Methyl Orange in presence of 2 ml of H(2)O(2) at an initial pH of 2.93 within 20 min. The pH range for effective decolourization (≥90%) was found to be 1-3. Leaching tests indicated that the activity of the catalyst was almost unaffected up to three consecutive cycles although ≤0.2 ppm of Fe ion was leached into treated water in each run.     

Numerical determination of stretch zone width (SZW) using tensile test data

There is an increasing effort to use critical stretch zone width (SZW) for the evaluation of initiation fracture toughness that is considered as geometry independent material property. The existing numerical SZW evaluation method is based on crack tip opening displacement measurement, which is evaluated using various definitions. This numerical method also does not define the critical stage for critical SZW measurement. This work attempts to establish a procedure for numerical determination of SZW, its critical value (SZW_c) and initiation fracture toughness using tensile test data. The proposed methodology also tries to explain the mechanism involved in the creation of stretched zone and thus defines the stage to calculate critical SZW. Numerical analyses have also been carried out to understand the role of crack tip constraint in standard fracture specimen during the blunting process and the tensile test sample.     

Decolorization of alkaline TNT hydrolysis effluents using UV/H(2)O(2)

Effects of H(2)O(2) dosage (0, 10, 50, 100 and 300 mg/l), reaction pH (11.9, 6.5 and 2.5) and initial color intensity (85, 80 and 60 color unit) on decolorization of alkaline 2,4,6-trinitrotoluene (TNT) hydrolysis effluents were investigated at a fixed UV strength (40 W/m(2)). Results indicated that UV/H(2)O(2) oxidation could efficiently achieve decolorization and further mineralization. Pseudo first-order decolorization rate constants, k, ranged between 2.9 and 5.4 h(-1) with higher values for lower H(2)O(2) dosage (i.e., 10 mg/l H(2)O(2)) when the decolorization occurred at the reaction pH of 11.9, whereas a faster decolorization was achieved with increase in H(2)O(2) dosage at both pH 6.5 and 2.5, resulting in the values of k as fast as 15.4 and 26.6 h(-1) with 300 mg/l H(2)O(2) at pH 6.5 and 2.5, respectively. Difference in decolorization rates was attributed to the reaction pH rather than to the initial color intensity, resulting from the scavenging of hydroxyl radical by carbonate ion. About 40% of spontaneous mineralization was achieved with addition of 10 mg/l H(2)O(2) at pH 6.5. Efficient decolorization and extension of H(2)O(2) longevity were observed at pH 6.5 conditions. It is recommended that the colored effluents from alkaline TNT hydrolysis be neutralized prior to a decolorization step.     

Room temperature Cl(2) sensing using thick nanoporous films of Sb-doped SnO(2)

Thick film resistive Cl(2) sensors were fabricated using SnO(2) doped with Sb. The nanocrystalline powders of Sb-doped SnO(2) synthesized by a sol-gel method were compressed into an 800?μm thick pellet. The fabricated sensors were tested against gases like Cl(2), Br(2), HCl, NO, NO(2), CHCl(3), NH(3) and H(2). The highest response to Cl(2) was achieved in 0.1% Sb doping where an exposure to 3?ppm of Cl(2) gas led to a 500-fold increase in device resistance. The high sensitivity to Cl(2) is accompanied by minor interference due to other gases at room temperature. It was found that the SnO(2) doped with 0.1% Sb exhibited high response, selectivity (>100 in comparison to the gases described above) and short response time (～60?s) to Cl(2) at 3?ppm level at room temperature.     

Modelling the time-dependent transmission rate for porcine circovirus type 2 (PCV2) in pigs using data from serial transmission experiments

Six successive transmission trials were carried out from 4 to 39 days post inoculation (DPI) to determine the features of the infectious period for PCV2-infected pigs. The infectiousness of inoculated pigs, assessed from the frequency of occurrence of infected pigs in susceptible groups in each contact trial, increased from 4 to 18 DPI (0, 7 and 8 infected pigs at 4, 11 and 18 DPI, respectively) and then decreased slowly until 39 days post infection (4, 2 and 1 pigs infected at 25, 32 and 39 DPI, respectively). The estimated time-dependent infectiousness was fitted to three unimodal function shapes (gamma, Weibull and lognormal) for comparison. The absence of infected pigs at 4 DPI revealed a latency period between 4 and 10 DPI. A sensitivity analysis was performed to test whether the parametric shape of the transmission function influenced the estimations. The estimated time-dependent transmission rate was implemented in a deterministic SEIR model and validated by comparing the model prediction with external data. The lognormal-like function shape evidenced the best quality of fit, leading to a latency period of 8 days, an estimated basic reproduction ratio of 5.9 [1.8,10.1] and a mean disease generation time of 18.4 days [18.2, 18.5].     

加权空间L2W(Rd)上的向量Weyl-Heisenberg标架

得到了加权空间L2W(Rd)上不存在Weyl-Heisenberg标架,除非权函数W(t)满足0＜AW(x)B＜+∞,a.e.,其中A,B为常数。     

Oxolinic acid photo-oxidation using immobilized TiO(2)

This work studied the photocatalysed oxidation of the antibiotic oxolinic acid (OA) in an annular reactor operated with immobilized TiO(2) on sintered glass cylinders (SGC). Experiments were carried out in 1l solution of OA (18mgl(-1)) at pH 9 with oxygen bubbling. Irradiation was performed with black light (36W). The reaction was monitored by COD, TOC and average oxidation state (AOS) calculations. The antibacterial activity of intermediates was followed using the inhibition halo technique on Escherichia coli cultures. The initial antibiotic concentration decreases in one order of magnitude after 60min irradiation, and was completely eliminated at 100min reaction. The TOC was reduced in 54% and the AOS reach values around +3 indicating the formation of low molecular weight carboxylic acids. The oxidation reaction fit well with the Langmuir-Hinshelwood kinetic model indicating the dependence of reaction rate with initial adsorption step. The antibacterial activity of the solution decreases with antibiotic removal, demonstrating that intermediates do not present antibiotic activity.     

D2声学测量系统的测试功能

D2声学测量系统,是美国AcoustX公司专为影院的综合测试和测量而设计的一套声学测量工具,已经通过了卢卡斯的认证.其中包括如图1所示的4支话筒及支架、D2调制器、D2控制器、USBPre 数字音频接口及Win|RTA测试软件(在所附光盘上).     

Active数据对象(ADO)在多参数测试系统中的应用

在多参数测试系统中,所设置的通道参数比较多,需存储、处理这些参数,数据库技术是一种理想的选择.本文讨论了Visual Basic 6.0的数据访问策略及其在测试系统中利用ADO操纵数据库的一些具体实现及其应该注意的事项.