Credit risk management is an integral part of banking business. By modifying the standard Markowitz model, the paper aims to study optimum credit portfolio with binary variable, which decides whether providing loads. The model can evaluate the cumulative risk and returns by considering the asset correlation and whether providing loads in the prospective of influencing risk indicators and profit rates. It enforces the empirical research of optimum portfolio by using the proposed model in this paper and the statistics offered by Standard & Poor's rating agency.

Because the risk factors for oil and gas transmission pipeline have complexity and fuzziness, and the factor weights are difficult to distribute. Therefore the entropy weight method was used to determine the factor weights, and the fuzzy comprehensive was used to evaluate the risk. First of all, the basic principle of entropy weight method and steps of fuzzy comprehensive evaluation method were briefly described. Then a section of oil conveying pipeline in Beijing area as an example, the risk evaluation index system was established and the factors weights were determined by using the entropy weight method. Finally, the risk level was determined by using the fuzzy comprehensive evaluation method, and the result was consistent with the judgment made by field experts. And according to the evaluation results, the corresponding prevention measures were proposed, so as to verify the feasibility of the method.

Credit rating is a comprehensive evaluation of the capability and the integrity of fulfilling economic commitments for the individual, the economy and financial instrument. The main function of credit rating lies in the credit risks revealment, which plays an irreplaceable role in increasing the efficiency of financial market. It is of great significance for the security of national finance and economy to have a proper credit rating. Different levels and time of default probability will be studied in this paper, which also includes further discussion on the risk premium and associated dependencies.

For offshore pipeline in a multilevel, multivariable, multiple nonquantitative factors, the lack of effective means of quantitative assessment of the conditions, the establishment of a multilevel system of pipeline safety evaluation index, combining analytic hierarchy process to determine the corresponding layers of indicators weight through the use of multilevel gray theory, the pipeline system for safety assessment would affect the level of risk to quantify treatment, given the reliability of inservice pipeline quantify the results. Multilevel grey evaluation method for less data, small sample, incomplete information and lack of experience with the uncertainty calculation was simple, direct, scientific and practical, and could be used to service for the offshore pipeline safety assessment.

In order to analyze and study our country’s real estate price’s and food price’s effects on inflation, the article chooses relevant statistics recorded from the first Quarter in 2000 to the fourth Quarter in 2010, and carries out the empirical test on the basis of the VAR model. As the result shows , inflation has a longterm and stable cointegration relationship with both the real estate price and the food price, besides, the increase of which are contributive to the occurrence of inflation. By comparison, however,the rise of the real estate price contributes more to the inflation, while the influence on inflation caused by the food price increasing last even longer.

Embedding and extracting algorithm for watermarking in the frequency domain based on the Fresnel and Fourier Hologram was proposed. The image watermarking was restored from the JPEG images with different compression ratios and the stability of watermarking image was compared between two different transformations. The result show that the image watermarking obtained by the proposed algorithm had perfect imperceptibility and stability. By comparison, however, the one based on the Fresnel Hologram had superiority in terms of stability.

A second-order nonlinear neutral delay differential equation was studied, and some sufficient conditions for existence of positive solutions for this equation were established. The advantage of the results is omitting the restriction condition of for any， must be negative. Furthermore, some examples were presented to illustrated that the results is more effective.

When the gas-liquid two-phase flows through tee pipeline, the distribution of two phase in two branch pipes is always uneven. There may be only gas branch in pipelines when it is serious, while the other export tube may be full of liquid. The numerical simulation on oil-gas two phase fluxion in different time by CFD was made and the oil and gas separation characteristics in branch pipes were get. The results show that there will be gas-liquid separation phenomenon in branch pipe when the oil and gas flow through branch pipe of tee pipeline, and close to the mouth branch the separation phenomenon is obvious. There is almost no separation phenomenon in certain distance of the branch mouth.

 

A type Ⅳ functional response predator-prey system was studied.The existence of global limit cycle was investigated by using qualitative analysis and the ideas of Poincaré-Bendixson theory, and some biological illustrations were given.