共查询到19条相似文献,搜索用时 62 毫秒
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连续两年对沿蒋家沟主沟(门前沟和多照沟交汇处至蒋家沟与小江交汇处)新发生的泥石流表层堆积物等距取样,测定热释光信号,计算出本底年龄值.研究表明:2010年泥石流表层堆积物的等效剂量和本底年龄沿沟向下游总体增大,2011年总体减小.2011年呈规律性波动,2010年相对于2011年规律不明显.2010年泥石流表层堆积物的辐照响应有较大差异,2011年则基本相同.随着支沟泥石流堆积物汇入主沟,本底年龄值先增大后减小,支沟泥石流堆积物的加入重置了主沟的退火起点.为确保泥石流释光测年机制的可对比性,应该选用对辐照响应较一致的样品,以不同的支沟退火过程为基础研究主沟的退火机制.本工作为进一步揭示泥石流的释光退火机制,开展古泥石流的释光测年提供技术支撑. 相似文献
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应用热释光技术对模拟阳光晒退后的泥石流标样和实际阳光晒退后的泥石流样品进行了热释光信号分层测定。实验结果表明:泥石流发生后经过曝光,样品积存热释光晒退程度随深度增加逐渐减弱,光晒退明显。光晒退随光照强度和时间增大而增强,深度增大,但深度变化总体不大。模拟的阳光晒退实验晒退深度达1 mm左右,实际阳光晒退实验晒退深度达6 mm左右。根据等效剂量随深度的变化可知,天然泥石流块状样由两次泥石流堆积形成。这一结果可为利用热释光技术开展泥石流测年和发生期次研究提供依据。 相似文献
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北京清水河流域现代稀性泥石流表层物质热释光本底初步研究 总被引:1,自引:1,他引:0
应用热释光技术对北京清水河流域稀性泥石流表层物质进行热释光信号测定,西北山沟、达摩沟、前桑峪沟三沟的形成区等效剂量平均值为48.38 Gy,流通区的平均值为91.75 Gy,堆积区的平均值为62.02 Gy。三个沟的表层泥石流物质本底小,说明原有的认为泥石流由于受物源本底影响无法测年的认识是有局限性的。这个事实可以为应用热释光对老泥石流测年提供依据,对于在泥石流堆积物质中应用热释光技术进行年代测定具有基础性的意义。 相似文献
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蒋家沟流域现代泥石流物质选频光释光特征初步研究 总被引:1,自引:0,他引:1
采用BG2003释光仪研究了云南蒋家沟流域的大凹子沟、蒋家沟、泥得坪沟及其多照沟4个泥石流沟底泥石流物质的选频释光特征,确定了发射光子的特征发射频率.在蓝光(480 nm)激发下,在波长为300nm、310nm、320 mn、400 nm和460nm下,大凹子沟与蒋家沟泥石流物质吸收的光子数都极为接近.用绿光(532nm)激发上述相同的样品,发现大凹子沟与多照沟底的泥石流物质吸收的光子数在波长为310nm、320 nm时也十分相近;进而在相同实验条件下,用绿光激发东北地区沙漠砂样品,得出沙漠砂物质的吸收光子数远大于泥石流物质的吸收光子数. 相似文献
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蒋家沟流域古泥石流物质选频释光特征研究 总被引:1,自引:0,他引:1
采用BG2003释光仪研究云南蒋家沟流域泥得坪台地、多照台地、大凹子沟、蒋家沟4个地点的8个古泥石流物质样品的选频释光特征,确定了发射光子的特征发射频率.在蓝光(488 nm)激发下,各样品的发射光子分别出现在波长为300、310、320、400、460 nm处.用绿光(532 nm)激发上述相同样品,发现其在波长为300、310、320、460 nm时的计数最为明显.进而确定出泥得坪堆积台地在不同时期泥石流物质释光谱图大体一致,但大凹子沟与多照古泥石流堆积台地不同时期的泥石流物质释光谱图表现出差异.以泥得坪堆积台地为例,该台地的上部、中上部、下部泥石流物质样品在绿光激发下,在波长为310、320、460 nm处,随辐照剂量的加大,样品的释光光子数递增.由这一规律可确定泥得坪堆积台地泥石流物质用于年龄测定的波长. 相似文献
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采用RGD-3B热释光仪对达朵泥石流堆积台地进行研究,以单片再生剂量法测定其剖面样品的等效剂量值(E.D.),结果表明:达朵台地剖面随深度的增加,埋藏时间增加,接受周围环境U、Th、K等的辐射剂量增多,等效剂量值总体上呈上升趋势,范围为92.91~155.38 Gy。说明采用热释光技术对古泥石流堆积台地进行年龄测定是可行的。确定达朵台地堆积时的年龄范围,对于云南小江流域划分泥石流活动期次、第四纪地层以及年代学标尺的建立具有基础性意义,同时为古泥石流堆积台地这种事件性的环境记录载体测年提供了一种新的思路和方法。 相似文献
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G. Kitis G.S. Polymeris V. Pagonis 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2010,268(6):592-598
This paper presents an attempt to isolate experimentally optically stimulated luminescence (OSL) signals which may originate from very deep traps (VDT) in quartz samples. As VDT we consider those traps which are responsible for TL glow peaks with a peak maximum temperature above a TL readout temperature of 500 °C. The basic experimental procedure used to isolate OSL signals from VDT is heating the quartz samples to 500 °C immediately before measuring the OSL signal. The study was carried out on eight quartz samples of very different origins; it is found that all eight samples exhibit OSL signals from VDT, and for a wide region of OSL stimulation temperatures. The OSL signal from VDT depends strongly on the type of quartz sample studied and on whether the sample was fired at high temperatures or not. The behavior of the OSL signal from VDT as a function of the stimulation temperature is found to be very different in fired and unfired samples. The thermal activation energy E for the OSL signals from VDT is obtained in both fired and unfired samples. The OSL signal from VDT in quartz samples fired at 800 °C for 1 h is very high, and the OSL curves consist of three well-defined components and a fourth slow component which is rather poorly resolved. The dose response of these components is obtained using a computerized deconvolution procedure for the dose region 0.5-300 Gy. The results are of importance for dating of ancient fired ceramics, since OSL signals from VDT could potentially extend appreciably the equivalent dose region toward both lower and higher values. 相似文献
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摇摆状态下气液两相流流型转变的实验研究 总被引:2,自引:0,他引:2
通过可视化观察和数码照片对摇摆状态下光滑有机玻璃管内气液两相流流型进行分类和定义,并分析了不同管径、摇摆角度以及摇摆周期对流型之间转变的影响.结果表明:在液相折算流速一样的情况下,管径增加、摇摆周期缩短或摇摆角度减小会使得环状流形成需要更高的气体折算流速;弹状流向搅混流转变所需气相流量则随着管径的减小、摇摆周期的增加或摇摆角度的减小而增加.而在气相折算流速一样的条件下,管径增加、摇摆周期缩短或摇摆角度增大会使泡状流产生需要更高的液相流量. 相似文献
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Jinbo Chen Lili Tong Jian Deng Wei Zeng 《Journal of Nuclear Science and Technology》2013,50(1):131-142
The intermittent flow behavior in a vertical annulus under a low-pressure condition was experimentally studied using a scaling experiment facility. The temperature and pressure variations in the channel had been obtained under the heat load ranging from 0 to 2.0 kW, initial subcooled water temperature ranging from 50 to 90 °C and length–diameter ratio ranging from 1.6 to 50. The effects of the heat load and length–diameter ratio of channel on the flow characteristics were investigated in detail. The experimental results showed that the steam bubbles erupted more frequently and regularly at a high heat load. The intermittent flow period decreased with increase of the heat load and aspect ratio. Based on the mechanism analysis, an empirical model considering the steam oscillation and the vapor–liquid interface rupture based on the experimental data was proposed. It was found that the accumulated steam basically increased linearly. The oscillation of the pressure and velocity decreased gradually with continuous steam accumulation. The Reynolds number of the liquid within the rising section was very small at the stagnation state since there was no forced circulation flow. Finally, a blockage was engendered in the pipeline with the steam accumulated. 相似文献