Determination to Weighting Coefficient of Combination Forecast Based on Rough Set Theory

The problem of determination to weighting coefficient is a key and difficulty for combination forecast. A method of determining weighting coefficient based on rough set theory is showed in this paper. Determining weighting coefficient is translated into estimating significance of attributes among rough set. A relation data model about combination forecast is established. Knowledge systems are built through making attribute value into eigenvalue. Under data moving, the weighting coefficients of a combination forecast model are computed by analyzing the dependence and significance of forecasting method for the predicted object. The proposed approach overcomes the subjectivity of traditional determination to weighting coefficient, avoids computing linear or nonlinear extremum problem and makes combination forecast more objective. The validity of the proposed approach is verified with a case.     

PROBABILISTIC EVALUATION FOR STEEL FRAME COLUMNS OF TALL BUILDINGS

Based on properties of parameters and test data of dom-estic steel,this paper analyses the reliability and partial coefficient forresistance of steel frame columns of tall builings.The result may serveas a scientific basis.It is not only for domestic steel instead of importedsteel in building tall steel structures,but also for compiling concerendstandards.     

Deformation of deep foundation pits due to excavation and dewatering considering the change of void ratio and permeability coefficient with current stress of soil

基于修正剑桥模型理论,推导了孔隙比e随土体当前应力变化的方程,同时比选了4组经典的描述渗透系数k随孔隙比变化的方程,选择了其中一组最佳的估算公式,编写ABAQUS用户子程序VOIDRI和USDFLD,以实现孔隙比和渗透系数随土体当前应力的变化。在此基础上,研究深基坑降水开挖所致的坑内外土体的变形、围护结构的变形及弯矩,得到以下结论：当考虑孔隙比随土体当前应力变化时,坑外地表沉降量、墙体的水平位移、地下连续墙的弯矩、坑底隆起量均大于孔隙比为定值时的情况;当考虑渗透系数随土体当前应力变化时,坑外地表沉降量、墙体的水平位移、地下连续墙的弯矩均小于渗透系数为定值时的情况,但同时考虑渗透系数和孔隙比变化情况时,其对坑底的隆起量的影响可以忽略不计。     

Discussion on Second-order Analysis of Variable-Section Beam-Column

In this paper, based on the discussion of orthogonal decomposition method for the buckling mode of unsymmetrical structure, taking the variable-section beam-column as an example, a simple and direct method of the second order analysis is presented. In the new method, the conception of enlargement coefficient brought forward by Timoshenko is developed. To begin with the curvature of the variable-section beam-column, the linear equations are set up. With their solution, a group of orthogonal buckling mode can be obtained. The primary deflection can be decomposed to a group of homomorphic deflection similar to buckling mode. Then, the group of deflection is multiplied by corresponding enlargement coefficient and plus the result, finally, the second-order total deflection can be obtained.     

Application of Matter Element Analysis in Assessment of Ambient Air Quality

A new method for assessment of ambient air quality is proposed by using matter element analysis.This model is simple and reasonable in assessment.The practical example is given,and compared with other methods.     

大麦多数量性状相关分析

穗长、穗粒重两性对小区产量直接影响较大;每穗实粒数和每穗不实粒两性状数对小区产量直接影响很小,但通过其他性状对小区产量的间接负影响很大;每穗总粒数对小区产量直接负影响很大,株高通过其他性状对小区产量间接正影响很大。     

高雷诺数对无量纲参数的影响

研究了高雷诺数对气体滚流强度和流量系数的影响。试验表明,气门升程和气道压差小时,难以形成充分发展的湍流,随着气门升程的增大,无量纲滚流强度和流量系数呈上升趋势,并且波动较大;充分发展时,可压缩气体的滚流强度和流量系数恒定不变,不可压缩气体的滚流强度比真实值偏大,而流量系数比真实值偏小,误差大小只与压力比有关,并随着压力比的增大而增大。     

喷油嘴流量系数对柴油机性能的影响

研究了喷油嘴流量系数变化对单缸直喷柴油机性能的影响。结果表明,增大流量系数对ZH1105柴油机标定工况和低速大转矩工况的烟度和燃油消耗率有明显影响。通过对燃油喷雾的分析,揭示了流量系数影响柴油机性能的原因。