CINRAD/SA雷达伺服系统稳定性对数据质量的影响

本文分析CINRAD/SA雷达伺服系统运行不稳定,主要有雷达方位俯仰定位超限、跳变、伺服故障等原因,造成雷达回波异常,并将回波异常分为3类。研究从雷达基数据中检测出雷达伺服系统方位俯仰的定位超限、跳变、故障等质控判别方法,及时发现雷达存在的异常回波问题,推送预警短信,指导台站及时进行维护维修,从而在源头上控制由于雷达伺服系统原因造成的异常回波资料生成,提升雷达数据和产品质量。     

GRAPES模式中三维科氏力计算及其效果评估

作为一种连续可压缩流体,大气具有分层流体特性,其状态变化可由牛顿第二定律、热力学第一定律、连续方程和理想大气状态方程组成的偏微分方程组描述。为了更加精细地描述GRAPES全球模式的动力过程,使模式大气更接近真实大气,在全球非静力模式GRAPES中考虑三维科氏力作用,通过重新构建半隐式半拉格朗日求解大气动力方程组的亥姆霍兹方程系数,在不改变求解方案的前提下实现对GRAPES模式动力过程的更新。然后采用在静力平衡基础上建立的三维大气理想试验对新的动力过程进行数值试验,检验其计算效果和数值稳定性。结果显示,考虑三维科氏力的模式动力框架计算稳定,提高了三维标量和矢量场的计算精度,在水平1°×1°分辨率模式中,平衡流试验第15天计算结果标量场Π'的l₁和l₂误差分别为0.00023和0.0004,而三维矢量场 V 的l₁和l₂误差分别为0.002和0.003,均较原模式误差小一个数量级。在罗斯贝-豪威兹波、地形罗斯贝波和斜压波试验中,新框架均表现出很高的计算稳定性和良好的计算效果。      

A STUDY OF NEAR SURFACE WIND PROFILES IN THE HEBEI COASTAL AREA BASED ON OBSERVATIONAL EXPERIMENTS

In order to provide wind profiles for the microscale numerical simulation of wind farm with complex terrain,using the 100 m tower atmospheric turbulence observation experiment data in 2010 in Hebei Province offered by National Climate Center, the variation characteristics of wind profile under the different atmospheric stability conditions are analyzed, and the wind profile expression based on the local similarity theory is established. The results show that:(1) In spring, the occurrence probability of unstable stratification in the Hebei coastal area is as high as 28%, and the probability of stable stratification is more than 43% while, in summer, the probability of occurrence of unstable stratification is as high as 80% with a lower probability for stable stratification; and(2) for stable stratification, the characteristics of atmosphere change is dramatic in terms of the vertical direction, which need to be treated layer by layer.According to the atmospheric turbulence observation experiment data above, under stable stratification, the relationship between the dimensionless velocity gradient and the stability ζ can be expressed as 1 +βmζ, with βm changing with the height: βm takes 4.1-4.3 under 30 m, βm takes 4.6-4.7 between 30-50 m, and βm takes 6.3-6.7 over 50 m.     

藏区公路地质灾害及其稳定性遥感解译

川藏区公路位于青藏高原腹地,地势高亢,气候寒冷。区内断裂构造十分发育,多以压扭性断裂为主,一般具有逆冲和逆掩性质,沿线发育的主要地质灾害有滑坡、崩塌、泥石流。通过遥感解译分析,在此基础上运用彩红外航空像片,确定了滑坡、崩塌、泥石流的解译标志,解析了其稳定性以及对公路的危害程度,为藏区公路灾害整治工程提供了地质依据。     

一个新的全局优化算法在岩土工程反分析中的应用

DCD(dynamic canonical descent)算法是一个新的全局优化算法,运用该法进行优化时,无需考虑目标函数的可微性,只要正确给定优化变量的优化区间,且该区间具有凸性,那么此算法就能很好地收敛于该区间的全局极小点.针对该算法,建立了相应的算法迭代格式.对数值试验和在岩土工程位移反分析的应用中引入该算法的迭代格式进行全局优化反演,其结果表明:该算法稳定性强,优化结果的可靠度高,收敛速度较快.     

Effects of surface forces and film elasticity on foam stability

The thin film pressure balance (TFPB) technique was used to determine the surface forces in foam films stabilized with flotation frothers such as n-pentanol, n-octanol, methyl isobutyl carbinol (MIBC), and polypropylene glycol (PPG). The results were compared with the foam stabilities measured experimentally and the film elasticities calculated using a model developed by Wang and Yoon [Wang, L., Yoon, R.-H., 2006a. Role of hydrophobic force in the thinning of foam films containing a nonionic surfactant. Colloids Surfaces A: Physicochem. Eng. Aspects, 282–283, 84–91.]. It was found that foam stabilities are controlled by both film elasticity and disjoining pressure, the relative contributions from each changing with frother type and concentration. At relatively low concentrations, frother dampens the hydrophobic force, an attractive component of the disjoining pressure, that destabilizes foams. At higher concentrations, elasticity plays a more important role in stabilizing foams.     

Evaluating cut slope failure by numerical analysis—a case study

Slope failure is very common phenomenon in hilly regions, especially in young techno active mountainous like Himalayas. It is hazardous because of the accompanying progressive movement of the slope-forming material. In order to minimize the landslide effects, slope failure analysis and stabilization requires in depth understanding of the process that governs the behavior of the slope. The present article mainly deals with the analysis of the stability of road cut slopes of Rudraprayag Area, Uttarakhand, India. The area experiences local as well as regional slides every year. Extensive field study was carried out along the road cut slopes. Laboratory experiments were conducted to determine the various Physio-mechanical properties of rock mass. These properties have been used as input parameters for the numerical simulation of slope using FLAC3D (Fast Lagrangian Analysis of Continua) including geological discontinuities. The computed deformations and the stress distribution along the failure surface are compared with the field observations. The study indicates that the overall slope is unstable except at the location E where slope is critically stable. The effects of instability have been thoroughly considered and remedial measures have been recommended.     

Experimental Investigation of the Upper Thermal Stability of Mg-rich Actinolite; Implications for Kiruna-Type Iron Deposits

The occurrence of actinolite in magnetite deposits of possiblemagmatic origin has prompted an experimental investigation ofthe upper thermal stability of Mg-rich actinolite to determinehow the stability of actinolite changes with increasing Fe content.Experiments were carried out primarily on the compositionalre-equilibration of natural tremolite [molar Fe/(Fe + Mg) =Fe-number = 0·014] in the presence of synthetic clinopyroxene(Ca_0·80Fe_0·67Mg_0·54Si_2·00O₆), syntheticpigeonite/orthopyroxene (Ca_0·08Fe_1·19Mg_0·70Si_2·02O₆),quartz, and water to a more Fe-rich actinolite over the rangeof 600–880°C, 1 and 4 kbar, at the Ni–NiO oxygenbuffer, for durations of 1–2 weeks. The bulk compositionof the mineral mixture is close to actinolite with Fe-number= 0·5. These experiments constitute a half-reversal ofthe amphibole composition, which, when approached from a Mg-richstarting composition, provides information on the minimum Fecontent of actinolite at a given temperature. Compositionalchanges were monitored by electron microprobe analysis of amphibolerim compositions and/or overgrowths on the original tremolite.At 4 kbar and 880–800°C, tremolite shows strong re-equilibrationwith overgrowths of an Fe-rich but low-Ca (1·7 > Ca> 1·4) actinolite; Fe-rich cummingtonite (Ca <0·7)begins to nucleate at 860°C. At 800–700°C, tremoliteshows weak compositional re-equilibration but strong nucleationof Fe-rich cummingtonite. Similar results were observed at 1kbar, with tremolite showing strong re-equilibration to low-Caactinolite at 790–600°C with cummingtonite nucleationat 800°C and below. The wide variation in Ca contents ofthe re-equilibrated amphiboles was unexpected. Additional univariantreversal experiments were carried out on the thermal decompositionof a natural actinolite (Fe-number = 0·22) from PleitoMelón, Chile, indicating the breakdown of actinoliteto clinopyroxene, orthopyroxene, quartz, and water at 780°Cand 1 kbar, and 850°C and 4 kbar. Considering only amphiboleswith Ca >1·7 a.p.f.u., the thermal stability of actinoliteis observed to decrease in a linear manner over the P–Trange investigated with a dT/dFe-number slope of –372°C/Fe-numberat 1 kbar and –546°C/Fe-number at 4 kbar. The highthermal stabilities (750–900°C) of actinolites withFe-numbers in the range of 0–0·4 overlap with therange of water-saturated melting for a typical andesite or tonalite.These conditions also overlap the field of experimental Fe–P-richmelt formation, suggesting that actinolite may have an igneousorigin in Kiruna-type ore deposits. KEY WORDS: actinolite; mineral stability; Kiruna deposits, thermodynamic values; cummingonite     

基于遗传算法的边坡稳定性分析

边坡稳定性分析的关键是如何确定最危险滑动面。遗传算法是一种全局优化分析方法,克服了一般优化方法容易陷入局部最优解的缺点。由于工程实际中边坡几何形状的不规则和材料的非均匀性,真正的临界滑动面形状并不是都能用圆弧来准确描述的,研究任意型滑面情况下的稳定性很有必要。为更加合理地进行边坡的稳定性分析,利用遗传算法来搜索模拟边坡的最危险滑动面,在工程实例中进行具体应用,得到了非圆弧型滑动面,与其他软件计算结果对比,表明本文算法精度更高,适应性更广。     

奇异Itô随机系统几个重要基础问题的研究进展

近年来,一类由Itô随机微分方程驱动的奇异随机系统因其在实际领域中的广泛应用而备受关注.然而,系统方程同时包含奇异矩阵和扩散矩阵,大大增加了分析问题的复杂性.本文首先概述了奇异Itô随机系统几个重要基础问题的研究进展,主要包括:系统方程解的存在条件、广义Itô公式、容许性定义及稳定性问题.同时针对不同文献对上述问题的研究结果提出了自己的观点.最后对以上基础问题研究待解决的问题进行了展望.