Do mesogranules exist?     

Haimin Wang 《Solar physics》1989,123(1):21-32

Applying spatial and temporal averaging techniques to several long sequences of Dopplergrams obtained at the solar disk center and near the limb, we confirmed the persistent supergranule velocity pattern. After excluding the 5-min oscillation and supergranule velocity fields from the disk center Doppler data, we find that the velocity structure shows a typical scale of 7 Mm, consistent with the scale of mesogranules found by November, Toomre, and Gebbie (1981) and November et al. (1982). However, this velocity pattern does not show properties of the cellular convection. It is not coherent for more than one hour, the period during which the raw Doppler images are averaged to remove the 5-min oscillation. Furthermore, we did not find convection patterns in the scale of mesogranules from the Doppler data obtained near the solar limb. We propose that the mesogranule velocity structure found by November et al. might be the uncorrected part of the 5-min oscillation and granule velocity.  相似文献   

含水量对高含冰量冻结砂土屈服面的影响     

杜海民  马巍  张淑娟  周志伟  穆彦虎 《冰川冻土》2019,41(3):579-586

以往关于冻土屈服特性的研究很少考虑含水量的影响,但实际工程中经常遇到的是变含水量情况,因此本文通过-5.0℃条件下高含冰量冻结砂土的一系列三轴压缩试验,系统地研究了含水量对屈服特性的影响,并且由此建立了带有含水量参数的偏应力-剪应变增量型关系式。试验结果表明：随含水量的变化,应力-应变曲线类型有明显变化,即在不同的含水量区间,含水量对硬化规律有不同的影响特性,因此为了使屈服函数的形式更加简单和提高拟合准确度,对于屈服函数的具体形式应该根据塑性剪应变（硬化参数）和含水量不同区间进行分别确定;当塑性剪应变较小时（0.00%~1.00%）,随含水量的增大,偏应力逐渐增加,而当塑性剪应变较大时（大于1.00%）,随含水量的增大,偏应力有一个先减小后增大的变化过程,并且42.0%可以作为含水量转折点;通过分段硬化原则建立的带有含水量参数的屈服函数与偏应力-剪应变的增量型关系式的模拟值与试验点基本相吻合,这说明得到的屈服函数与偏应力-剪应变的增量型关系式可以用于不同含水量条件下屈服面和偏应力-剪应变曲线的预测。  相似文献   

乌尔米耶盐湖的综合利用          下载免费PDF全文

马培华  李海民  张彭熹 《盐湖研究》1999,(1)

伊郎乌尔米耶盐湖是中东地区最大的盐湖之一。本文针对该湖卤水的和当地自然地理条件,对其卤水中钾,钠,溴,镁等资源综合利用的可能性,合理的开发规模,可行的化学加工路线,未来建厂的选址,环境问题及技术经济可行性等问题进行了研究。结果表明,该湖的溴和钠资源具有重要的开发价值。  相似文献   

Counter-streaming Mass Flow and Transient Brightening in Active Region Loops     

Qiu  Jiong  Wang  Haimin  Chae  Jongchul  Goode  Philip R. 《Solar physics》1999,190(1-2):153-165

An active region loop system was observed in a decaying active region for three hours by TRACE and BBSO in a joint campaign on September 27, 1998. Continuous mass motion was seen in Hα offband filtergrams throughout the three hours, and some UV loops were exhibited transient brightenings. We find that: (1) cool material was flowing along the loops at a speed of at least 20 km s^?1. Further, in Hα red and blue wings, we see mass motion along different loops in opposite directions. This is the first report of a counter-streaming pattern of mass motion in an Hα loop system. (2) Transient brightenings of different UV loops at different times were observed at C?iv 1550 Å. These brightened UV loops were located in the same region and at the same altitudes as the Hα loops. The observations show a clear correlation between the transient brightenings of UV loops and mass motion in Hα loops. (3) Both footpoints of the loop system were located in regions of mixed magnetic polarities. Frequent micro-flares at one footpoint of the loops with small-scale brightenings spreading along the loop leg were observed before the brightening and rising of one C?iv loop. Similar to the case of a filament, the continuous mass motion along the loops seems important for maintaining the cool Hα loop system at coronal height. There may be an indication that the mass motion in cool Hα loops and the correlated transient brightening of the active region loops were due to the small-scale chromospheric magnetic reconnection at the footpoint regions of the loop system.

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粤东地区早白垩世花岗质岩浆作用及其成因演化     

赵希林  余明刚  刘凯  毛建仁  叶海敏  邢光福 《地质论评》2012,58(5):965-977

粤东地区出露有大埔黑云母花岗岩、大埔黑云母钾长花岗岩和揭西黑云母钾长花岗岩3种岩石类型,大埔黑云母花岗岩和揭西黑云母钾长花岗岩的LA-ICP-MS锆石U-Pb年龄分别为136.3±0.6Ma和134.9±0.4Ma,属于晚中生代早白垩世,而非前人认为的晚侏罗世;3种岩石在主量元素上总体具有富硅、铝,碱含量中等,贫铁、镁、钙、钛、磷的特征,属于高钾钙碱性的弱过铝质岩石;大埔黑云母花岗岩的δEu负异常中等,具略向右倾的轻稀土富集模式,可能是由时代相当于元古宙的富砂屑岩部分熔融形成的;大埔黑云母钾长花岗岩、揭西黑云母钾长花岗岩具有中等—强的δEu负异常,稀土配分模式为海鸥型,二者在野外分布上紧密共生,时间上比较接近,在地球化学上表示出连续变化的趋势,具有相似的同位素组成,可能是由时代相当于元古宙的陆壳富泥质变质沉积岩部分熔融形成的,是同一岩浆演化到不同阶段的产物.  相似文献   

赣南与钨锡矿化有关的九曲二云母花岗岩的   总被引：2，自引：0，他引：2  

赵希林  毛建仁  刘凯  叶海敏  王开虎 《地质论评》2013,59(1):83-96

九曲二云母花岗岩与钨锡成矿关系密切,锆石SHRIMP U-Pb和LA-ICP-MS U-Pb测试结果分别为169±8Ma和169.6±0.8Ma,属于中生代中侏罗世.九曲岩体的钾长石和白云母的Ar-Ar坪年龄分别为100.80±0.76Ma和169.7±1.2 Ma,反等时线年龄分别为104.1±3.5 Ma和170.4± 2.2 Ma,分别代表了钾长石和白云母的结晶年龄.九曲岩体具有两阶段的冷却速率,在早阶段其冷却曲线为近垂直于年龄轴的直线,晚阶段的冷却速度为2.90℃/Ma;在地球化学特征上总的特点是富硅、碱,贫钙、镁、钛、磷;DI介于95.04～ 95.57之间,反映了岩体经历了高程度分异演化作用;属于过铝质的高钾钙碱性系列岩石;稀土配分模式呈稍向左倾的重稀土富集型,Eu强烈负异常,εNd(t)值介于-9.51～-10.12之间,计算的二阶段Nd模式年龄T2DM介于1.83 ～1.87Ga,推测其可能是由时代相当于元古宙的陆壳富泥质变质沉积岩部分熔融形成的S型花岗岩类,较低的K/Rb值暗示了在演化过程中有挥发分流体参与并经历了较强的分异作用,是岩浆演化到晚期阶段的产物.  相似文献   

Hard x-ray and Microwave Flux Spectra of the 2 November 1991 Solar Flare     

Lee  Chik-Yin  Wang  Haimin 《Solar physics》2000,195(1):149-164

We analysed the hard X-ray and microwave flux spectra of the solar flare (BATSE No. 1791) on 2 November 1991, which started at 16:11:03 UT and ended at 16:56:10 UT. This flare is particularly interesting because of its deep cyclic intensity modulation. Data are available simultaneously from the 16-channel BATSE/LAD hard X-ray and 45-frequency OVRO microwave database. We quantitatively compare the time variations in profiles of the hard X-ray spectral photon index, the 50 keV X-ray flux, and microwave spectral indices (at both high and low frequency ends). As expected, the X-ray photon spectral index decreases as the hard X-ray flux increases. This pattern appears in all the sub-peaks. This is consistent with previous observations that hard X-ray emission hardens at the emission peak. However, the behaviour of the high-frequency microwave index is unexpected. We observe an anti-correlation between the high-frequency microwave index and the hard X-ray photon index during the course of the flare. Finally, we study the arrival time of microwave flux peaks as a function of frequency and find that the microwave peak at a higher frequency comes earlier than that at a lower frequency. A maximum delay of 72 s is found among the main peaks at different frequencies. Shorter delays are found for the other five sub-peaks.  相似文献   

Automatic Solar Filament Detection Using Image Processing Techniques     

Ming Qu  Frank Y. Shih  Ju Jing  Haimin Wang 《Solar physics》2005,228(1-2):119-135

We present an automatic solar filament detection algorithm based on image enhancement, segmentation, pattern recognition, and mathematical morphology methods. This algorithm cannot only detect filaments, but can also identify spines, footpoints, and filament disappearances. It consists of five steps: (1) The stabilized inverse diffusion equation (SIDE) is used to enhance and sharpen filament contours. (2) A new method for automatic threshold selection is proposed to extract filaments from local background. (3) The support vector machine (SVM) is used to differentiate between sunspots and filaments. (4) Once a filament is identified, morphological thinning, pruning, and adaptive edge linking methods are used to determine the filament properties. (5) Finally, we propose a filament matching method to detect filament disappearances. We have successfully applied the algorithm to Hα full-disk images obtained at Big Bear Solar Observatory (BBSO). It has the potential to become the foundation of an automatic solar filament detection system, which will enhance our capabilities of forecasting and predicting geo-effective events and space weather.  相似文献   

Precise Dating and Geological Significance of the Caledonian Shangyou Pluton in South Jiangxi Province     

MAO Jianren  ZENG Qingtao  LI Zilong  HU Qing  ZHAO Xilin  YE Haimin 《《地质学报》英文版》2008,82(2):399-408

The zircon SHRIMP dating age for the Shangyou granites is 464±11 Ma. The geological feature of the pluton is consistent with the isotopic age, which shows that it is a product of Caledonian orogenesis. The Shangyou granites are regarded as peraluminous crust-derived granites to possess the typical geochemical characteristics of calc-alkaline rocks on the active continental margin with enriched Si, K, Al （A/CNK -- 1.11 on average）, HREE, Rb, U, Th and heavily depleted V, Cr, Co, Ni, as well as Ti-Y, Nb-Ta, Zr, Sr, P and Ba, to be commonly corundum normative （av C -- 1.44）. The Shangyou granites with higher 87Sr/86Sr ratios （0.707126-0.712186）, ENd（t） values （-7.29 to -10.22） and （tDM） values （1.52-1.63 Ga）, which are considered to result from partial melting of continental crust metamorphic sedimentary rocks with relatively low of crust maturation degree corresponding to the Middle Proterozoic, to have some possible contributions of mantle-derived components. The Shangyou granites are regarded as post-collision granites, which were formed in a transitional tectonic setting from compression to extension in the Middle Ordovician period after the Yangtze plate was subducted beneath the Cathaysian plate. The Ar-Ar total ages of K-feldspar and biotite are 292.1 Ma and 295.5 Ma respectively, which have recorded information of a late-stage thermal alteration event.  相似文献   

Video image selection studies of granules,pores, and penumbral flows near a large sunspot     

Harold Zirin  Haimin Wang 《Solar physics》1989,119(2):245-255

An excellent high-resolution movie in the green continuum was produced by shift-and-add treatment of two 60-min videotapes obtained at the Big Bear Solar Observatory. We have studied the digitized images by direct measurement, cross-correlation techniques, and correlation tracking. The seeing-limited resolution was about 0.3 arc sec.While the cross-correlation lifetime for granules is about five minutes, we find that actually tracking the growth and decay of a granule gives lifetimes from 10 to 22 minutes, the longest lifetimes pertaining to the largest granules. The longer lifetime comes from tracking the granule while it undergoes large changes in size and shape, while the cross-correlation lifetime is just the time in which it grows by a factor two. All the granules followed began as small elements, grew to some size, and either faded (88%), exploded (2%) or were hit by an exploding granule (10%). The major variation in granule structure appears to be due to substantial variations in the dark lanes, which often double in width.The granulation shows the typical exploding granule behavior; we find the probability that any granule will be affected by an exploding granule during its lifetime to be 10%. We also observed a larger scale explosion covering about 10 granules. This explosion was marked by rapid (1 km s^–1) outward flux of the granules.We tracked the development of six small pores, one of which could be followed for two hours. The latter showed four maxima of absorption separated by about 30 min each, virtually disappearing in between. Another was observed to form in about 20 min, but no changes occur in less than granule lifetime.We confirm the inflow in penumbral fibrils observed by Muller. The inflow velocity is about 0.5 km s^–1, and all bright spots disappear into the umbra. The inflow which affects bright and dark features in the penumbral fibrils, is also observed in the smaller spots. We surmise that the Evershed flow is limited to the areas between the bright fibrils. We confirm granular outflow outside the penumbra.  相似文献