独立分量分析在机械振动信号分离中的应用

针对机械运转时工作环境复杂,监控采集的信号多为混合信号的情况,研究了如何从混合信号中分离出相对应的各振动源信号.采用独立分量分析的分离方法,通过对极大似然估计的目标函数进行简化,基于无需选择学习率的快速不动点迭代的优化方法,选用可同时估计亚高斯和超高斯独立成分的非线性函数估计概率密度,推导出了该算法.最后,对工程中几种特殊情况下的混合信号进行仿真和实验室实测的分离试验.结果表明,算法简单易行,具有快速稳定收敛的性质.     

基于贝叶斯估计的起重机械主梁的可靠性预测

针对起重机械主梁工作环境的复杂性和在相同工作环境下可靠性数据不足的问题,将贝叶斯估计方法和数据拟合相结合,以主梁的退化量作为性能参数,建立了起重机械主梁在工作环境下的可靠性预测模型;利用贝叶斯估计方法最大限度地将工作现场数据和历史试验数据相结合,及时更新主梁在工作环境下性能参数的分布函数,进而估计工作环境下不同时刻主梁的可靠度,最后采用最小二乘法估计主梁的可靠性函数.预测结果表明,起重机械主梁失效满足参数为(9.290,225.9)的2参数威布尔分布,得到为了满足主梁98％的可靠度要求,最小的维修间隔周期为149天.     

Weldability of low-alloy steels in submersion-arc welding at high linear energies

Results of analysis of investigations of welded joints produced in welding low-alloy high-strength 07G2NDMFBT steel at linear energies up to 6 kJ/mm show that the proposed combinations of welding materials and the technology of multi-arc submerged-arc welding result in high hot-cracking resistance and high properties of the weld metal. However, regardless of the high cold-cracking resistance of the steel, in welding at high heat inputs there is a considerable degradation of the structure and the toughness of the metal in the coarse-grained region of the heat-affected zone decreases under the effect of the welding thermal cycle. Consequently, it is concluded that the weldability of this steel is limited and it is therefore necessary to apply restrictions in the practical application of the processes with high heat input.     

凝析气藏工业气流量计算方法

国土资源部颁发的《DZ/T 0217-2005 石油天然气储量计算规范》给出了我国东部地区气藏不同埋藏深度下估算的工业气流标准,但该标准没有考虑气藏储渗条件的影响,也没有明显体现凝析油成分对工业气流的影响,不适合凝析气藏的对照使用。根据投入产出平衡原理,提出了凝析气藏工业气流计算模型,以我国西部凝析气藏为例,根据目前各项参数测算了相应的工业气流,绘制了工业气流图版。提出的方法也适用于含硫化氢等其他复杂成分气藏工业气流的计算。     

横向各向同性介质Thomsen近似公式的适用范围

Thomsen为横向各向同性（TI）介质提出的各向异性参数和线性近似公式被广泛采用,但目前对Thomsen近似公式的适用范围的认识仍很模糊。针对这一问题,研究了TI介质P波和SV波Thomsen近似公式最大相对误差随各向异性参数变化的特征以及近似公式的适用范围。研究结果表明,波速比α0/β0=1．5时,在-0．12≤ε≤0.16且-0.16≤δ≤0.24,或｜ε-δ｜〈0.17（ε和δ为正）时,P波相速度近似公式的最大相对误差不超过l％,随着了0／0的增大,适用范围略有扩大。SV波近似公式的精度比P波要低一些,在｜ε｜≤0.1且｜δ｜≤0.14,或｜ε-δ｜〈O．02（ε和占为正）时,SV波相速度平方线性近似公式的最大相对误差不超过1％,随着α0/β0的增大,适用伪范围明显缩小。总体来说,P波近似公式适用范围较大,对一些中等强度的各向异性也适用;SV波近似公式尤其是群速度近似公式适用范围很小,必要时需要使用高阶近似或者精确解。     

截尾数据下一类半参数回归模型的估计

讨论了一类半参数回归模型y =x′β+g(t′α) +e .假定y被随机变量T右侧截尾 ,T与y独立 ,T～G。在G已知和未知两种情况下 ,构造了α、β和g(·) 的强相合估计     

A test object with a line width less than 10 nm for scanning electron microscopy

Data are given on the test object for scanning electron microscopy in which the components (ridges) are of trapezoidal profile and have large angles of inclination for the side walls. The width of the top surface of a projection is less than 10 nm. Methods have been developed for measuring such dimensions of test objects on standard scanning electron microscopes. __________ Translated from Izmeritel'naya Tekhnika, No. 8, pp. 20–23, August, 2008.     

Analysis of errors in the measurement of the volume of natural gas under standard conditions using measurement complexes that incorporate counters

A comparative analysis of techniques used to estimate the errors of measurement complexes that incorporate counters, using as an example measurements of the volume of natural gas from the Tyumen region in the range of absolute pressure 0.1-10 MPa, is conducted. Practical recommendations are given.Translated from Izmeritelnaya Tekhnika, No. 11, pp. 30–35, November, 2004.     

An approach to accidents modeling based on compounds road environments

The most common approach to study the influence of certain road features on accidents has been the consideration of uniform road segments characterized by a unique feature. However, when an accident is related to the road infrastructure, its cause is usually not a single characteristic but rather a complex combination of several characteristics. The main objective of this paper is to describe a methodology developed in order to consider the road as a complete environment by using compound road environments, overcoming the limitations inherented in considering only uniform road segments. The methodology consists of: dividing a sample of roads into segments; grouping them into quite homogeneous road environments using cluster analysis; and identifying the influence of skid resistance and texture depth on road accidents in each environment by using generalized linear models. The application of this methodology is demonstrated for eight roads. Based on real data from accidents and road characteristics, three compound road environments were established where the pavement surface properties significantly influence the occurrence of accidents. Results have showed clearly that road environments where braking maneuvers are more common or those with small radii of curvature and high speeds require higher skid resistance and texture depth as an important contribution to the accident prevention.     

基于P2P技术的文件分发结构的研究

论述了三种基于P2P技术的文件分发结构及文件分发过程,讨论了这三种结构的文件分发时间与接收节点数量和文件分块数量之间的关系,比较了各自的特点和缺点.