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The geometrical structure of disperse system is described by fractal theory, which is based on the easily measurable parameters, such as the occupation probability, the diameters of disperse pellets, etc. A fractal model of thermal conductivity of a disperse system with even particles has been developed with the aid of the analogy between the heat conduction and percolation. The measurement of the thermal conductivity in the disperse system was carried out by the cutout hot wire method

This paper presents a new technology using Bismuth-film to determinate lead instead of mercury film. It is proved in the experiment that, in the optimum measuring situation (when the pH is 4, deposition time is 150s, and the deposition potential is 0.8.), the lead concentration and stripping peak current shows a good linear relationship in the measuring range of 10 to 110ug/L, which is I=0.1002C+0.0539. The experimental analysis shows that the concentration of lead in tea samples is 1.667μg / g, and the recovery rate is 91.2% ~ 101.8%. It is proved that the method of bismuth film electrode is used to measure lead with advantages of convenience, speediness, sensitivity and accuracy, etc.

Corrosion associated with microorganisms has been recognized for over 50 years and yet the study of microbiologically influenced corrosion (MIC) is relatively new. MIC can occur in diverse environments. Industrial cooling water from rivers, lakes and sea water contain lots of microorganisms which are able to grow and multiply under certain conditions when pH, water temperature and sunlight etc are suitable. MIC is one of key cause of heat exchanger faults. MIC of heat exchanger materials in cooling waters has caused expensive unplanned outages, the need for local repairs and, in some cases, completes system replacement. Sulfate-reducing bacteria (SRB) are the main harmful bacteria in circulating cooling water. Under anaerobic conditions, SRB reproduce a lot to produce mucus, which speed up the formation of corrosion, erode the metal equipment, plug the pipeline, affect the efficiency of heat transfer, and bring a lot of inconvenience to the production. The corrosion behaviors of 304 stainless steel induced by SRB were studied by measuring the polarization curves, electrochemical impedance Spectrum, weight loss measurements of fore-and-aft biocorrosion, and electrochemical noise method. The electrochemical noise signal of 304 stainless steel corrosion were de-noised by using a wavelet threshold de-noising method, which made the quadratic biorthogonal spline wavelet as the mother wavelet and adopted an soft threshold processing function. The result showed that the slope of cathodic polarization curves measured included with SRB is lower than the one obtained without SRB, while the slope of anodic polarization curves is higher than it. It is concluded that the process of anode polarization was repressed at the presence of SRB. With the growth of the culture time, the value of electrochemical impedance without bacteria reduced at first, then rose, while with bacteria fell at all times. It indicated that SRB accelerated the corrosion of stainless steel. With the dipping time, a biofilm, under which corrosion products congregate to form local battery corrosion, was formed on the surface of stainless steel, so that the serious pitting corrosion is induced. The results from electrochemical noise method showed that the quadratic biorthogonal spline wavelet much smoother and it can remove the noise from the electrochemical noise effectively, and can effectively identify the location of the sudden changes in the signal and accurately reflect the useful information of the signal. The more useful information and data about biocorrosion induced by SRB are also gotten.

This paper provides a comprehensive analysis on cooling tower fouling data taken from seven 15.54 mm I.D. helically ribbed, copper tubes and a plain tube at Re = 16000. A new mathematical model has been developed. The mass transfer coefficient Km is calculated through three analogies, which are Prandtl analogy, Von-Karman analogy, and j factor analogy. Fouling deposition is assumed to be determined by two processes, which are corresponding to heat flux and fluid friction. Von-Karman analogy is proved the best analogy among the three. Series of semi-theoretical fouling correlations as a function of the product of area indexes and efficiency indexes were developed. They were applicable to different internally ribbed geometries. The correlations can be directly used to assess the fouling potential of enhanced tubes in actual cooling tower water situations.Copyright © 2010 by ASME

In this paper, we use the electronic tongue as a detection tool and Normal Pulse voltammetry (NPV) as the measuring principle to identify the sulfate-reducing bacteria and iron bacteria. The main task is to classify the two bacteria on the reference of broth culture medium. We adopted non-supervised (principal component analysis PCA) and supervised (partial least squares PLS and artificial neural network ANN) pattern recognition to process data, and compared the performance of model for supervised identification, the experimental results showed that ANN was better. The recognition rate of ANN in the training set came to 100%, and in the test set came to 91.67%. The results prove that the electronic tongue with ANN pattern recognition system is a good choice to identify the two types of bacteria.

The principle on the electrochemical noise detected by using wavelet transform was described briefly. In the electrochemical noise measurements, there is always having noise more or less. If they are analyzed directly, the useful information and data can not be got from them, so they must be de-noised. Wavelet analysis has many advantages that other signal processing tools do not have, it can provide characteristics of the signal both in time domain and frequency domain, it has high resolution, and high resulting accuracy. The electrochemical noise of 304 stainless steel corrosion which is measured in the solution of sulfate-reducing bacteria were de- noised by using a wavelet threshold de-noising method, which made the quadratic biorthogonal spline wavelet as the mother wavelet and adopted an soft threshold processing function. The results showed that the quadratic biorthogonal spline wavelet much smoother and it can remove the noise from the electrochemical noise effectively, and can effectively identify the location of the sudden changes in the signal and accurately reflect the useful information of the signal.

Wavelet analysis has many advantages that other signal processing tools do not have, it can provide characteristics of the signal both in time domain and frequency domain, it has high resolution, and high resulting accuracy. As a result of these characteristics, this article attempts to adopt the appropriate Wavelet filtering method in de-noising the signal of AC impedance techniques of the signal processing, and thus the noise was eliminated, the further analytical work was prepared.

Support vector machine (SVM) is applied for classification in this paper. The SVM operates on the principle of structure risk minimization; hence better generalization ability is guaranteed. This paper discussed the basic principle of the SVM at first, and then we chose SVM classifier with polynomial kernel and the Gaussian radial basis function kernel (RBFSVM) to recognize the cancer samples (benign and malignant). Selecting some value for parameters to know different performance each parameter produces to outputs. The simulations of the recognizing of two class samples have been presented and discussed. Results show the RBF SVM can classify complicated patterns and achieve higher recognition rate. SVM overcomes disadvantages of the artificial neural networks. The results indicate that the SVM classifier exhibits good generalization performance and the recognition rate above 93.33% for the testing samples. This means the support vector machines are effective for classification.

The application of wavelet neural network based on Levenberg-Marquardt Optimization to predict heat exchanger fouling is reported in this paper. We construct a 6-6-1 network according to the fouling monitor principle and parameters, the modeling of the wavelet neural network programmed with MATLAB, and trained with Levenberg-Marquarde Optimization algorithm, all training data came from the Automatic Dynamic Simulator of Fouling and input the network after normalized processing and reclassification. Simulations show that the relative error of fouling prediction is less than 0.71 percent, and wavelet neural network can be used to predict heat exchanger fouling, and has the rapid convergence rate and perfect prediction precision, the Levenberg-Marquarde Optimization algorithm can also improve convergence rate of wavelet neural network to a certain extent.

Heterotrophic bacteria is detected and counted by National Standard Method of China at present, i.e. flat dish numberation, which has the disadvantages of subjectivity, big error and low efficiency because of relying on manual counting. A method of rapid determination of heterotrophic bacteria in industrial cooling water is developed. After converting the original image into a greyscale one, we removed the edge image of culture dish on the basis of the principle that three unco-linear points can determine a circle. Then binarization with the greyscale-weighted threshold method, distance transform and watershed algorithm to segment overlapping colonies are applied, and finally four-connected searching algorithm was used to mark and count the colony. It has been proved that the method greatly improves the accuracy and efficiency of the heterotrophic bacteria counting and the counting results are not affected by shapes or sizes of the colony. It has been revealed that colony counting based on image processing method can be an effective way.

In allusion to the present heterotrophic bacteria colony counting method having the disadvantages of subjectivity, big error and low efficiency, we proposed a recognition method for heterotrophic bacteria colony based on SVM. After a series of pre-processing and segmentation to the acquired colony image, 6 feature parameters such as: area, perimeter, equivalent diameters of colony individual and non-colony ones were extracted. Then we adopted SVM to recognize them and the recognition rate of 98.7% was obtained. This means the effectiveness of the feature extraction method and the feasibility of support vector machines used for heterotrophic bacteria colony recognition.

To adopt protective measure and guarantee safe and economic operation for heat exchanger, it's necessary to accurate monitor and evaluate fouling and corrosion of heat exchanger. Point at the imperfection of present method to monitor fouling and corrosion of heat exchanger, A new practical on-line equipment was developed based on the soft-measure technology for fouling with easily measured parameters and the mental corrosion rate monitoring technology with the weak polarization method, and introduces mainly the measuring principle, the structure, the performance and the application of the monitoring equipment based on the above principle.