不同误差结构对运用股分析(CA)模型求算鱼类自然死亡系数影响的初步研究

当鱼类一个世代的资源量和渔获量数据已知,POPE(1972)提出的股分析(cohortanalysis,CA)模型可以用来求算鱼类的自然死亡系数(M)。在以往的计算过程中来自模型和数据的误差往往被忽略。文章讨论了用股分析模型求算M的方法,并运用广义线性模型(generalizedlinearmodel,GzLM)探讨了3种不同误差结构(正态,对数正态和伽马)对求算结果的影响。蒙特卡罗(MonteCarlo)模拟分析显示,当数据的噪音(即变异系数coefficientofvariation,CV)小于大约10%时可以得到M较好的估计值。不同的误差结构会影响M的估算,其中对数正态分布的GzLM误差得到了最好的结果。构造了长寿命小自然死亡系数和短寿命大自然死亡系数的2个鱼类种群,模拟结果表明这种方法更适用于寿命短而自然死亡系数大的种群。同样假设以上3种误差结构,将该方法应用到黄海鳀鱼(Engraulisjaponicus)渔业数据上。与其它2种误差结构相比,对数正态的GzLM误差结构同样得到了良好的结果。由于低龄鱼具有较为准确的观测数据,其M的估计值好于高龄鱼。

Ratio K: a New Way of Metering and Evaluating the Risk and Return of Stock Investment

Although widely used, both the Markowitz model and VAR (Value at Risk) model have some limitations in evaluating the risk and return of stock investment. By the analysis of the conceptions of risk and return, together with the three hypotheses of technological analysis, a novelty model of metering and evaluating the risk and return of stock investment is established. The major indicator of this model , risk-return ratio K, combines the characteristic indicators of risk and return. Regardless of the form of the risk-return probability density functions, this indicator K can always reflect the risk-return performances of the invested stocks clearly and accurately. How to use the model to make optimum investment and how to make portfolio combined with clustering analysis is also explained.

Return threshold model analysis of two stock markets： Evidence study of Italy and Germany＇s stock returns

This paper discusses the model construction and the association between the Italy and the Germany＇s stock markets. The period of study data is from January 3, 2000 to June 30, 2008. This paper also utilizes Student＇s t distribution to analyze the proposed model. The empirical results show that the two stock markets are mutually affected each other, and the dynamic conditional correlation （DCC） and the bivariate asymmetric-GARCH （1, 2） model is appropriate in evaluating the relation between them. The empirical result also indicates that Italy and Germany＇s stock markets show a positive relationship. The average value of correlation coefficient equals to 0.8424, which implies that the two stock markets return volatility have a synchronized influence on each other. In addition, the empirical result also shows that there is an asymmetrical effect between Italy and the Germany＇s stock markets, and demonstrates that the good news and bad news of the stock returns＇ volatility will produce the different variation risks for Italy and the Germany＇s stock price markets.

Stress Transfer Modeling at the Interface of Cemented Prosthesis and Femur

Objective：To model the stress transfer at the interface of the cemented prosthesis and femur, an axisymmetric model of the interfacial stress transfer was established. Methods ： Assuming that the prosthesis, the cement and the femur were concentric cylinders with linear elastic and isotropic properties, distributions of the axial stresses in the prosthesis, the cement and the femur as well as the interfacial shear stresses at the prosthesis/cement interface and the cement/femur interface in the axial direction were obtained from the established axisymmetric stress transfer model. Results ： Interfacial failure was the main form for the prosthesis/cement/femur structure under external loads. Considering the residual thermal stresses, it was more likely to produce the mixed failure form than the pure shear failure form. Since the cement had a relatively high thermal expansion coefficient, the thermal effect accelerated the interface failure and thus aggravated the stress shielding effect. Due to a relatively high thermal residual temperature difference, the interfacial debonding and femur failure was more likely to occur for the cobalt-chromium alloy prosthesis material than the Ti-6A1-4V alloy prosthesis material. Conclusion： Assuming that the prosthesis, the cement and the femur are concentric cylinders with linear elastic and isotropic properties, distributions of the axial stresses in the prosthesis, the cement and the femur as well as the interfacial shear stresses at the prosthesis/cement interface and the cement/femur interface in the axial direction was obtained using the basic equations of axisymmetric elastic mechanics when the prosthesis bears the compressive stresses. Interface failure is the main failure form for the prosthesis/cement/femur structure under external loads. The thermal effects accelerate the failure of the prosthesis/cement interface and the cement/femur interface and the relaxation of the prosthesis, and then aggravates the stress shielding effect of the femur. Also, the thermal effects decrease the efficiencies of the interfacial stress transfer to some extent since it alleviates the failure of the interface and the femur, which was confirmed by the clinical results.

An Empirical Study on the stock Price of Modeling

the model in time series analysis are widely used in the field of economy. We often use the model in time series to analyze data, but without regard to the rationality of the model. In this paper, we introduce and analyze Ping An Of China（601318） shares at the opening price（2013/01/04-2013/07/04）.The model is established by analyzing data. Modeling steps of ARIMA model and GARCH model are presented in this paper. The data whether ARIMA model is suitable by white noise. Or the data whether GARCH model is suitable by since the correlation of variance test. By comparing the analysis, it selects a more reasonable model.

IS TECHNICAL ANALYSIS INFORMATIVE IN UK STOCK MARKET? EVIDENCE FROM DECOMPOSITION-BASED VECTOR AUTOREGRESSIVE(DVAR) MODEL

The paper proposes a new approach -- The decomposition-based vector autoregressive （DVAR） model to scrutinize the predictability of the UK stock market. Empirical studies performed on the monthly British FTSE100 index over 1984-2012 confirm that the DVAR model does provide informative forecasts for both in-sample and out-of-sample forecasts. Trading strategies based on the DVAR forecasts can Significantly beat the simple buy-and-hold, which demonstrates the valuable information provided by technical analysis in the UK stock market.

COMPLEX SYSTEM ANALYSIS OF MARKET RETURN PERCOLATION MODEL ON SIERPINSKI CARPET LATTICE FRACTAL

This paper investigates the statistical behaviors of fluctuations of price changes in a stock market.The Sierpinski carpet lattice fractal and the percolation system are applied to develop a new random stock price for the financial market.The Sierpinski carpet is an infinitely ramified fractal and the percolation theory is usually used to describe the behavior of connected clusters in a random graph.The authors investigate and analyze the statistical behaviors of returns of the price model by some analysis methods,including multifractal analysis,autocorrelation analysis,scaled return interval analysis.Moreover,the authors consider the daily returns of Shanghai Stock Exchange Composite Index,and the comparisons of return behaviors between the actual data and the simulation data are exhibited.