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91.
地史转折期的生态系   总被引:7,自引:2,他引:7  
生态系的演变是地球各圈层系统耦合关系变化的直接标志。地史转折期的生态系具有复杂的生物内涵,在绝灭—残存—复苏过程中,各生物类别的演替遵循着一定的生存型式。大绝灭后生态系复苏的原动力是绝灭后迁入避难所的复活类型和大绝灭末期高压环境中产生的祖先类型的新生和辐射发展。全面了解绝灭后生态系的组成和结构,对于正确认识地史转折期,即圈层耦合结点处的地质作用型式和过程具有重要作用。  相似文献   
92.
本文分析了特征点应满足的几种条件,给出了一次范围最小(L1)法,最小二乘法以及粗差探测法进行特征点粗差定位方法,并以模拟实例为例对它们进行了比较,得出了一些有意义的结论。  相似文献   
93.
静力弹塑性分析(Pushover Analysis)的基本原理和计算实例   总被引:86,自引:3,他引:86  
阐述了美国两本手册FEMA273/274和ATC-40中关于静力弹塑性分析的基本原理和方法,给出了利用ETABS程序进行适合我国地震烈度分析的计算步骤,并用一框剪结构示例予以说明,表明Pushover方法是目前对结构进行在罕遇地震作用下弹塑性分析的有效方法。  相似文献   
94.
地热井井位确定研究——以豫煤二队院内地热井为例   总被引:2,自引:0,他引:2  
通过对龙门地热田地质构造、地下水运动特点及规律的研究,提出了在地热田内寻找地下热水的富水靶区,并推算了其范围。又以地面调查、地面电法等手段进行了验证,确定了地下热水富水带的具体位置及地热井施工井位,一次成功地打中千米以下地热水的富水区,为地热田内寻找、开发地下热水总结了经验,丰富了深井及地热田找水的理论。  相似文献   
95.
玉米淀粉废水回收及处理研究   总被引:1,自引:1,他引:1  
采用调节等电位点—超过滤组合技术对玉米淀粉废水的资源回收和处理进行研究,确定了最佳工艺参数。结果表明通过调节等电位点,可回收粗蛋白用作家禽饲料,同时废水中的CODcr、TSS和BOD5去除率分别可达48.8%、49.6%和27.2%以上,减轻了后续超过滤处理压力;通过超过滤进一步处理,出水COD、TSS和BOD去除率分别达91.3%、92.5%和95.1%。  相似文献   
96.
When comparing solutions for the propagation of SH waves in plane parallel layered elastic and viscoelastic (anelastic) media, one of the first things that becomes apparent is that in the elastic case the location of the saddle points required to obtain a high frequency approximation are located on the real p axis. This is true of the branch points also. In a viscoelastic medium this is not typical. The saddle point corresponding to an arrival lies in the first quadrant of the complex p-plane as do the branch points. Additionally, in the elastic case the saddle point and branch points lie on a straight line drawn through the origin (the positive real axis in the complex p-plane), while in the viscoelastic case this is generally not the case and the saddle point and branch points lie in such a manner as to indicate the degree of their complex values.In this paper simple SH reflected and transmitted particle displacement arrivals due to a point torque source at the surface in a viscoelastic medium composed of a layer over a half space will be considered. The path of steepest descent defining the saddle point in the first quadrant will be parameterized in terms of a real variable and the high frequency solutions and intermediate analytic results obtained will be used to formulate more specific constraints and observations regarding saddle point location relative to branch point locations in the complex p-plane.As saddle point determination for an arrival is, in general, the solution of a non-linear equation in two unknowns (the real and imaginary parts of the complex saddle point p 0), which must be solved numerically, the use of analytical methods for investigating this problem type is somewhat limited.Numerical experimentation using well documented solution methods, such as Newton's method, was undertaken and some observations were made. Although fairly basic, they did provide for the design of algorithms for the computation of synthetic traces that displayed more efficient convergence and accuracy than those previously employed. This was the primary motivation for this work and the results from the SH problem may be used with minimal modifications to address the more complicated subject of coupled P-SV wave propagation in viscoelastic media.Another reason for revisiting a problem that has received some attention in the literature was to approach it in a fairly comprehensive manner so that a number of specific observations may be made regarding the location of the saddle point in the complex p-plane and to incorporate these into computer software. These have been found to result in more efficient algorithms for the SH wave propagation and a significant enhancement of the comparable software in the P-SV problem.  相似文献   
97.
98.
基于共反射点叠加的观测参数选择   总被引:1,自引:2,他引:1  
在地震勘探数据处理中,通常采用的共中心点(CMP)叠加技术对于复杂的地质构造难以取得好的效果。若通过从道间距、覆盖次数等观测参数与目标层地层倾角、共反射点离散度的关系出发,并结合模型正演,对复杂构造地层的观测参数选取进行优化,使之能对目标层尤其是逆断层下降盘的阴影层段进行较充分的“照明”,即可得到共反射点叠加剖面,这对共反射点叠加是一项有益的研究。  相似文献   
99.
A gravity and magnetic survey has been carried out with the purpose of investigating geophysical features of the crusts beneath three geological provinces in western Argentina: Cuyo Precordillera, the Sierras Pampeanas of San Juan and La Rioja, and Famatina System, the results of which are displayed in three maps: Bouguer anomaly, total field magnetic anomaly and total field reduced to the pole.

The top and bottom boundaries of the magnetized crust were calculated from power-density spectra of the total-field anomalies from our terrestrial database in 90 2D windows. The depths obtained for the bottom of magnetized crust are assumed to correspond to Curie point depths. The values thus obtained for the Precordillera range between 29 and 40 km, whereas for the Sierras Pampeanas, in the Sierra de Pie de Palo, and other mountain chains along the Bermejo-Desaguadero lineament or Valle Fértil lineament, such depth ranges between 20 and 35 km. These results are consistent with Curie point depths determined on different continental regions in the world.

A map of regional heat flow has been prepared in the present work based on the depth of the Curie point isotherm, which shows that heat flow patterns in Precordillera are different from those found in Sierras Pampeanas.

A significant heat flow extending in Northeast-Southwest direction seems to be directly related to Juan Fernández Ridge trace.

The results of the present investigations also point out a possible relationship between the base of the magnetized crust and the boundary separating the brittle from the ductile crustal regime.  相似文献   

100.
于春生 《现代测绘》2004,27(4):33-34
通过实例推导幂函数对建筑物沉降进行回归分析,并且得出较为精确的结果,同时也说明在选择回归函数的时候,还会受到很多条件影响。  相似文献   
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