混凝土复合混合料活性研究

以活性较低的锂盐渣与粉煤灰复合研制一种新型的、具有较高活性的复合混合料 ,经试验研究表明 ,该复合混合料中锂盐渣掺量不同对复合混合料的火山灰活性影响较大 ,对混凝土 7d、2 8d、6 0d、180d各龄期的强度影响也较大 ,且复合混合料混凝土比粉煤灰混凝土强度平均高出 30 %以上。采用扫描电镜及X衍射进行了形貌和物相分析。得出在复合混合料中锂盐渣存在最佳掺量范围 ,而复合混合料火山灰活性与混凝土龄期关系较大 ,6 0d内复合混合料火山灰活性较突出 。

汞压法对水泥浆和掺合料水泥浆孔隙分析

硬化后混凝土材料具有细观、微观多孔隙特征,即使配制良好的高性能混凝土,也含有微孔隙和微裂纹。混凝土内部孔隙率及孔径分布对混凝土材料的性质有重要影响,如强度、变形、容重、导热性、吸水性、抗渗性及耐久性等;而矿物掺合料可改变混凝土内部孔隙的分布,从而影响混凝土的性能;因此,对混凝土材料内部孔隙的研究也是混凝土微观研究的一个重要方面。

Correlation-weighted least squares residual algorithm for RAIM

The Least Squares Residual(LSR)algorithm,one of the classical Receiver Autonomous Integrity Monitoring(RAIM)algorithms for Global Navigation Satellite System(GNSS),presents a high Missed Detection Risk(MDR)for a large-slope faulty satellite and a high False Alarm Risk(FAR)for a small-slope faulty satellite.From the theoretical analysis of the high MDR and FAR cause,the optimal slope is determined,and thereby the optimal test statistic for fault detection is conceived,which can minimize the FAR with the MDR not exceeding its allowable value.To construct a test statistic approximate to the optimal one,the CorrelationWeighted LSR(CW-LSR)algorithm is proposed.The CW-LSR test statistic remains the sum of pseudorange residual squares,but the square for the most potentially faulty satellite,judged by correlation analysis between the pseudorange residual and observation error,is weighted with an optimal-slope-based factor.It does not obey the same distribution but has the same noncentral parameter with the optimal test statistic.The superior performance of the CW-LSR algorithm is verified via simulation,both reducing the FAR for a small-slope faulty satellite with the MDR not exceeding its allowable value and reducing the MDR for a large-slope faulty satellite at the expense of FAR addition.

An enhanced least squares residual RAIM algorithm based on optimal decentralized factor

The Least Squares Residual(LSR)algorithm is commonly used in the Receiver Autonomous Integrity Monitoring(RAIM).However,LSR algorithm presents high Missed Detection Risk(MDR)caused by a large-slope faulty satellite and high False Alert Risk(FAR)caused by a small-slope faulty satellite.In this paper,the LSR algorithm is improved to reduce the MDR for a large-slope faulty satellite and the FAR for a small-slope faulty satellite.Based on the analysis of the vertical critical slope,the optimal decentralized factor is defined and the optimal test statistic is conceived,which can minimize the FAR with the premise that the MDR does not exceed its allowable value of all three directions.To construct a new test statistic approximating to the optimal test statistic,the Optimal Decentralized Factor weighted LSR(ODF-LSR)algorithm is proposed.The new test statistic maintains the sum of pseudo-range residual squares,but the specific pseudo-range residual is weighted with a parameter related to the optimal decentralized factor.The new test statistic has the same decentralized parameter with the optimal test statistic when single faulty satellite exists,and the difference between the expectation of the new test statistic and the optimal test statistic is the minimum when no faulty satellite exists.The performance of the ODFLSR algorithm is demonstrated by simulation experiments.

水泥石孔隙结构模型的研究

混凝土材料具有细观、微观多孔隙特征,即使配制良好的高性能混凝土,也含有微孔隙。混凝土内部孔隙率及孔径分布对混凝土材料的性质有重要影响,混凝土内部孔隙主要分布在水泥浆硬化后的水泥石体中,因此,研究水泥石孔隙结构和创建水泥石孔隙模型对混凝土材料的研究具有重要意义。