Physical properties of white-light flares derived from their center-to-limb distribution

We compare the observed center-to-limb distribution of 86 white-light flares (WLFs) with calculated distributions derived from five flare models, each covering different heights, temperatures, and densities in the solar atmosphere. Considering the limited statistics and the possibility of selection effects in reporting WLFs, the following results may be considered tentative: (1) WLFs cannot be modeledsolely by high-altitude optically thin sources, by optically thin chromospheric sources, or by photospheric sources located less than 150 km above the ₅₀₀₀ = 1 level; (2) middle photospheric sources extending somewhat higher than 150 km provide the best fit to the observed center-to-limb distribution, and (3) middle photospheric sources not exceeding 150 km altitude combined with chromospheric or higher-altitude sources are acceptable. An important feature of this work is that the methods used in the analysis are entirely independent of spectral analysis; yet spectral analysis has provided evidence for both photospheric and chromospheric components in WLFs.Operated by the Association of Universities for Research in Astronomy, Inc., under cooperative agreement with the National Science Foundation. Partial support for the National Solar Observatory is provided by the USAF under a Memorandum of Understanding with the NSF.     

Theoretical mean wave resistance of precursor soliton generation of single-layer flow

Theoretical mean wave resistance and regional division of the energy of single-layer flow over topogra-phy is studied at the near-resonant region in the weakly nonlinear, long wave limit. The theoretical meanwave resistance is determined in terms of the 1st and 2nd conservation laws of the fKdV equation. It isproved by the asymptotic mean method that the theoretical mean wave resistance depends only on the intensityand moving velocity of the topography. The theoretical results of this paper are in good agreement withnumerical calculations. Comparisons between the theoretical and numerical results showed that the theoryof the present paper holds for any small compact topography.     

文安地震现场观测与思考

简要介绍了文安地震现场观测工作,它不是一般意义上的地震现场观测,所以本文总结了现场监测工作的成功与不足,提出了改进地震应急观测工作的建议和思考。     

云南天文台新型斑点象探测系统

斑点成象技术能有效地消除地球大气湍流的不良影响,实现地基大型天文望远镜的衍射受限分辨率成象,其所需的原始数据是天文目标及参考星的一系列的短曝光斑点象,它们取自望远镜的终端设备：斑点象探测系统。文中对比该技术对原始数据的要求：介绍了云南天文台研制的新型斑点象探测系统的结构和性能。实际观测结果表明,该系统基本能满足要求。     

Processing and interpretation of data from a sonobouy refraction seismic section in the East China Sea shelf marginal ridge

Refraction seismic data obtained from a sonobuoy (SB7) in the East China Sea shelf marginal ridge was processed and interpreted. Intercept times and layer velocities were used to set up a one-dimension depth-velocity model based on which a two-dimenssion depth-velocity crustal model was established through two-dimension ray-tracing. The computation results showed that the upper crustal depth-velocity model beneath lineSB7 is composed of four layers with primary wave velocities of 1.80–2.20, 2.85–2.90, 3.24–3.34 and 4.55–6.00 m/s respectively. Neighbouring reflection seismic data and data on the East China Sea (ECS) regional geology were used to study the relationship between the velocities and their formation ages and also the contact relationship between the velocity boundaries. Contribution No. 3259, from the Institute of Oceanology, Chinese Academy of Sciences. Project 49376266 supported by NSFC.     

相对蒸散在冬小麦干旱宏观评估中的应用

利用最新的Ｐｅｎｍａｎ－Ｍｏｎｔｅｉｔｈ参考蒸散估算方法,计算了华北各地历年小麦各发育阶段的相对蒸散。根据水分亏缺引起的不同减产程度,确定冬小麦各发育阶段干旱指标,并据此分析了小麦干旱程度及发生概率。建立了冬小麦干旱影响综合评估模式。结果表明,干旱指标农业意义明确,分析评估符合实际。利用综合考虑冬季严寒和生育期内各阶段水分状况的模式进行农业干旱影响评估的尝试取得了较好的效果。     

江西省修水县地质灾害及减灾防灾措施探讨

崩塌、滑坡、山洪、山坡型泥石流为修水县主要地质灾害类型。通过对地质灾害形成条件的分析,进而提出防灾减灾措施     

近百年齐齐哈尔市的气温变化

通过对齐齐哈尔市近百年来气温变化的多时间尺度结构和局部化特征的分析，得出齐齐哈尔市的气温不仅存在准2a、4a、4～6a和8a左右的年际尺度的周期性变化，也存在40～60a的年代际尺度的周期性变化；而且具有明显的突变特征，40～60a尺度的冷暖交替分别出现在1924、1955和1989年。     

天山北缘的地壳结构和1906年玛纳斯地震的地震构造

长86km、南北向横跨乌鲁木齐坳陷的深地震反射剖面，揭示了北天山山前地壳的薄皮构造特征．共深度点叠加剖面的石河子以南部分显示了天山北缘平行山体的第一和第二排背斜构造．与双程时间分别为2.5～3.0s和5.5～6.0ｓ的反射事件对应的滑脱构造，将地壳深部构造与地表逆断裂 褶皱构造联系在一起．玛纳斯断裂以铲形方式向下延伸，在2.5ｓ左右深度归并于第一滑脱面，向南与清水河断裂汇合．在5.5～6.0ｓ深度上为与玛纳斯下背斜相连的主滑脱面．它们最终汇集到准噶尔南缘断裂．石河子以北的坳陷沉积深度达12～14km．沿剖面的莫霍界面深度在准噶尔盆地为45ｋｍ 左右，往南加深至50ｋｍ．对该区域内的深地震测深剖面和布格重力异常资料的分析结果，与深反射剖面的地壳结构图象具有一致性．深地震反射剖面通过1906年玛纳斯7.7级地震宏观震中区，共深度点叠加剖面用于推断玛纳斯7.7级地震与北天山山前地壳构造之间的关系:玛纳斯地震属于一类褶皱地震，其发震构造是由准噶尔南缘断裂、清水河逆冲断裂、滑脱面和玛纳斯浅部断坡组成的断层系．