全站仪三角高程新方法及精度估算

利用传统三角高程原理和方法推导一种全站仪三角高程测量新方法计算公式。该方法的优点是在观测的过程中不需要量测仪器和棱镜高,从而达到提高精度的目的;并利用误差传播定律进行精度估算和分析,通过与《工程测量规范》中相应的水准闭合差比较,得出在一定条件下该方法可以代替三、四等水准测量。此方法用在施工测量中可以大大地提高工作效率和缩短工程工期。     

基于NDVI纹理的山东丘陵地区SPOT-5影像果园信息识别研究

胶东半岛是我国重要的水果生产基地,及时有效地获取果园信息,对指导当地水果生产具有重要意义。在遥感信息提取中,纹理特征是一种有效的辅助信息,但在原始影像中地形阴影对纹理特征有较大影响。本文提出了一种利用NDVI影像的纹理特征和光谱特征从SPOT-5影像自动识别果园信息的方法,消除了地形阴影的影响,取得了86.40%的识别精度。     

混合模型中的层三角变换估计

提出了有着广泛应用的混合线性模型中参数估计的一种新方法,称层三角变换估计。将该变换用于检验和估计中,将产生一束套用于全面分析混合线模型的计算过程,这些过程在计算是稳定的,而且节省空间。     

Effect of irregular structural configuration on floor acceleration demand in hill‐side buildings

A suite of reinforced‐concrete frame buildings located on hill sides, with 2 different structural configurations, viz step‐back and split‐foundation, are analyzed to study their floor response. Both step‐back and split‐foundation structural configurations lead to torsional effects in the direction across the slope due to the presence of shorter columns on the uphill side. Peak floor acceleration and floor response spectra are obtained at each storey's center of rigidity and at both its stiff and flexible edges. As reported in previous studies as well, it is observed that the floor response spectra are better correlated with the ground response spectrum. Therefore, the floor spectral amplification functions are obtained as the ratio of spectral ordinates at different floor levels to the one at the ground level. Peaks are observed in the spectral amplification functions corresponding to the first 2 modes in the upper portion of the hill‐side buildings, whereas a single peak corresponding to a specific kth mode of vibration is observed on the floors below the uppermost foundation level. Based on the numerical study for the step‐back and split‐foundation hill‐side buildings, simple floor spectral amplification functions are proposed and validated. The proposed spectral amplification functions take into account both the buildings' plan and elevation irregularities and can be used for seismic design of acceleration‐sensitive nonstructural components, given that the supporting structure's dynamic characteristics, torsional rotation, ground‐motion response spectrum, and location of the nonstructural components within the supporting structure are known, because current code models are actually not applicable to hill‐side buildings.     

Analytic wave series solution of out-of-plane(SH) waves diffraction by an almost semi-circular shallow cylindrical hill

A closed-form wave equation analytic solution of two-dimensional scattering and diffraction of outof-plane(SH) waves by an almost semi-circular shallow cylindrical hill on a flat, elastic and homogeneous half space is proposed by applying the discrete Fourier series expansions of sine and cosine functions. The semi-circular hill problem is discussed as a special case for the new formulated equation.Compared with the previous semi-circular cases solutions, the present method can give surface displacement amplitudes which agrees well with previous results. Although the proposed equation can only solve the problem of SH-waves diffracted by almost semi-circular shallow hills, the stress and displacement residual amplitudes are numerical insignificantly everywhere. Moreover, the influences of the depth-towidth ratio(a parameter defined in this paper to evaluate the shallowness of the topography of hills) on ground motions are presented and summarized. The limitations and errors of truncation from Graf's addition theorem and Fourier series equations in the present paper are also discussed.     

Experimental Study on Cross-Flow Induced Vibrations in Heat Exchanger Tube Bundle

Vibration in heat exchangers is one of the main problems that the industry has faced over last few decades. Vibration phenomenon in heat exchangers is of major concern for designers and process engineers since it can lead to the tube damage, tube leakage, baffle damage, tube collision damage, fatigue, creep etc. In the present study, vibration response is analyzed on single tube located in the centre of the tube bundle having parallel triangular arrangement (60°) with P/D ratio of 1.44. The experiment is performed for two different flow conditions. This kind of experiment has not been reported in the literature. Under the first condition, the tube vibration response is analyzed when there is no internal flow in the tube and under the second condition, the response is analyzed when the internal tube flow is maintained at a constant value of 0.1 m/s. The free stream shell side velocity ranges from 0.8 m/s to 1.3 m/s, the reduced gap velocity varies from 1.80 to 2.66 and the Reynolds number varies from 44500 to 66000. It is observed that the internal tube flow results in larger vibration amplitudes for the tube than that without internal tube flow. It is also established that over the current range of shell side flow velocity, the turbulence is the dominant excitation mechanism for producing vibration in the tube since the amplitude varies directly with the increase in the shell side velocity. Damping has no significant effect on the vibration behavior of the tube for the current velocity range.     

Deltaic soil behavior classification using CPTu records—Proposed approach and applied to fifty-four case histories

For the past four decades, the CPT has played a key role in onshore and offshore soil investigations. One of the main applications of cone penetration test (CPT) is the soil behavioral classification. Most of the developed methods for soil identification using CPT and CPTu (piezocone) data are well categorized for common soils, such as clays, silts, and sands. Soils with low resistance or more compressibility generally involve problems in geotechnical engineering practice and construction projects. Consequently, these unusual deposits require further evaluation and more detailed data. Five major groups of problematic soils including: liquefiable, sensitive, peaty, collapsible, and expansive soils have been considered in this study. One hundred and forty CPT and CPTu test records were collected from fifteen countries. Sixty-one of the records are related to difficult soils. A brief comparison is performed for currently used soil behavioral classification charts, such as by Campanella et al. (1985 Campanella, R. G., P. K. Robertson, D. Gillespie, and J. Greig. 1985. Recent developments in in-situ testing of soils. Proceedings of 11th International Conference on Soil Mechanics and Foundation Engineering, ICSMFE, San Francisco, Vol. 2, 849–54. [Google Scholar]), Robertson (1990 Robertson, P. K. 1990. Soil classification using the cone penetration test. Canadian Geotechnical Journal 27 (1):151–58. doi:10.1139/t90–014[Crossref], [Web of Science ®] , [Google Scholar]), Jefferies and Davies (1991 Jefferies, M. G., and M. P. Davies. 1991. Soil classification using the cone penetration test: Discussion. Canadian Geotechnical Journal 28 (1):173–76. doi:10.1139/t91–023[Crossref], [Web of Science ®] , [Google Scholar]) and Eslami and Fellenius (1997 Eslami, A., and B. H. Fellenius. 1997. Pile capacity by direct CPT and CPTu methods applied to 102 case histories. Canadian Geotechnical Journal 34 (6):886–904. doi:10.1139/cgj-34–6-886[Crossref], [Web of Science ®] , [Google Scholar]). Analysis based on CPT data indicates that a few commonly used charts recognize relatively well problematic deposits. However, further studies are needed to increase the accuracy and capability of methods. Existing charts have some problems due to the limitations of the nature of rectangular charts based on two axes. A new format of classification chart, i.e., triangular form containing cone tip resistance (q_c), sleeve friction (f_s), and pore pressure (u₂) is proposed for soil identification which can be realized in practice. The proposed chart with more accuracy and less scattering of data than the previous charts is able to identify soil types particularly for deltaic soils.     

汶川地震山脚震害特征及机理分析1

汶川地震和以往地震现场震害调查表明,局部场地地形对震害的影响明显,其中,山脚房屋震害程度明显低于山顶和水平地表土层场地.针对这一震害特征,本文以汶川主震的地形效应观测强震动记录和人工爆破山体地形地震动观测记录为基础,通过数据分析,结合动力集中质量中心差分有限元法进行数值模拟分析,进一步揭示了山脚房屋震害轻微的特征不仅与其所在场地条件良好有关,更与山脚所处山体底部的几何位置直接相关.     

大兴安岭南东段龙头山银铅锌多金属矿床成矿地质特征与远景评价

文章阐述了龙头山银铅锌多金属矿床的地质特征,初步确定了矿床的成矿期与成矿阶段、蚀变作用与蚀变分带,以及控矿构造系统与空间变化等;通过合理的探矿工程并借助于先进的地球物理探测手段,基本探明了Ⅰ、Ⅱ号矿带内矿体的空间产出形态、规模和产状,大致查明了矿石的类型、结构构造以及矿化特征,并合理地圈定了矿体;通过综合取样分析,估算并预测了远景资源储量.     

渤海残留盆地油气地球物理研究综述

本文阐述了海相残留盆地的概念,对近年来渤海海相残留盆地油藏的烃源岩、储集体、构造带及圈闭类型分布特征的研究进展进行总结,并对国内外海相盆地潜山油藏勘探历程进行概述,重点对海相残留盆地及潜山油藏综合地球物理研究现状及进展进行综述,并对未来发展趋势进行展望.