Retrieving chlorophyll content and equivalent water thickness of Moso bamboo(Phyllostachys pubescens) forests under Pantana phyllostachysae Chao-induced stress from Sentinel-2A/B images in a multiple LUTs-based PROSAIL framework

Biochemical components of Moso bamboo(Phyllostachys pubescens)are critical to physiological and ecological processes and play an important role in the material and energy cycles of the ecosystem.The coupled PROSPECT with SAIL(PROSAIL)radiative transfer model is widely used for vegetation biochemical component content inversion.However,the presence of leaf-eating pests,such as Pantana phyllostachysae Chao(PPC),weakens the performance of the model for estimating biochemical components of Moso bamboo and thus must be considered.Therefore,this study considered pest-induced stress signals associated with Sentinel-2A/B images and field data and established multiple sets of biochemical canopy reflectance look-up tables(LUTs)based on the PROSAIL framework by setting different parameter ranges according to infestation levels.Quantitative inversions of leaf area index(LAI),leaf chlorophyll content(LCC),and leaf equivalent water thickness(LEWT)were derived.The scale conversions from LCC to canopy chlorophyll content(CCC)and LEWT to canopy equivalent water thickness(CEWT)were calculated.The results showed that LAI,CCC,and CEWT were inversely related with PPC-induced stress.When applying multiple LUTs,the p-values were<0.01;the R2 values for LAI,CCC,and CEWT were 0.71,0.68,and 0.65 with root mean square error(RMSE)(normalized RMSE,NRMSE)values of 0.38(0.16),17.56μg cm-2(0.20),and 0.02 cm(0.51),respectively.Compared to the values obtained for the traditional PROSAIL model,for October,R2 values increased by 0.05 and 0.10 and NRMSE decreased by 0.09 and 0.02 for CCC and CEWT,respectively and RMSE decreased by 0.35μg cm-2 for CCC.The feasibility of the inverse strategy for integrating pest-induced stress factors into the PROSAIL model,while establishing multiple LUTs under different pest-induced damage levels,was successfully demonstrated and can potentially enhance future vegetation parameter inversion and monitoring of bamboo forest health and ecosystems.

Equivalent oxide thickness scaling of Al_2O_3/Ge metal-oxide-semiconductor capacitors with ozone post oxidation

Aluminum-oxide films deposited as gate dielectrics on germanium （Ge） by atomic layer deposition were post oxidized in an ozone atmosphere. No additional interfacial layer was electron microscopy and X-ray photoelectron spectroscopy detected by the high-resolution cross-sectional transmission measurements made after the ozone post oxidation （OPO） treatment. Decreases in the equivalent oxide thickness of the OPO-treated Al2O3/Ge MOS capacitors were confirmed. Furthermore, a continuous decrease in the gate leakage current was achieved with increasing OPO treatment time. The results can be attributed to the film quality having been improved by the OPO treatment.

Prediction of Apparent Equivalent Thickness Using the Spontaneous Potential Method and Its Application to Oilfield Development

The upper spontaneous potential produced by oil and gas accumulation is of a stable potential field, and its intensity is directly proportional to the content of the source and inversely proportional to the radius apart from the source. Theoretical research and practical results show that anomalies of spontaneous potential can indicate oil-bearing sandstone bodies and locate the areas of oil and gas accumulation. In oil areas which have fewer reservoir beds, the petroleum reservoir thickness can be predicted by determining the linear relationship between potential intensity and apparent equivalent thickness. In the Weixing （卫星） oilfield, which is devoid of sufficient reservoir beds, its apparent equivalent thickness can be predicted by the linear equation h= -0.19x＋0.74. On the basis of geological research, we use the spontaneous potential method to predict the equivalent thickness, helping in the selection of the most appropriate drill sites to enhance the probability of successful well boring so as to serve the next round development of the oilfield.

Science Letters: Equivalent thickness of materials of fused silica and stainless steel in the flow of microtubes

The deviation of flow characteristics from the predictions of the conventional theory for microtubes was attrib- uted to the change of fluid viscosity resulted from the interactions between the molecules on solid wall and in fluid. The degree of this departure is dependent on the microtubes materials. A concept of equivalent thickness with which conventional theory can be used to predict the flow in microtubes without modifying the fluid viscosity was put forward. The values of equivalent thickness for fused silica and stainless steel materials were determined as 1.8 μm and 1.5 μm, respectively, by repeated numeri- cal simulation.

Nonlinear phase error analysis of equivalent thickness in a white-light spectral interferometer

A white light spectral interferometry based on a Linnik type system was established to accurately measure the thin film thickness through transparent medium.In practical work,the equivalent thickness of a beam splitter and the mismatch of the objective lens introduce nonlinear phase errors.Adding a transparent medium also increases the equivalent thickness.The simulation results showthat the equivalent thickness has a significant effect on thin film thickness measurements.Therefore,it is necessary to perform wavelength correction to provide a constant equivalent thickness for beamsplitters.In the experiments,some pieces of cover glasses as the transparent medium were added to the measured beam and then a standard thin film thickness of 1052.2±0.9 nm was tested through the transparent medium.The results demonstrate that our system has a nanometer-level accuracy for thin film thickness measurement through transparent medium with optical path compensation.

Analytic Computation Method of the Equivalent Thickness of Superposition Multi-Throttle-Slices of Twin-Tubes Shock Absorber

By elastic mechanics, the deformation of single throttle-slice for shock absorber was analyzed, the formula of its deformation was established. According to the relation of the deformation of multi-throttle-slices with the pressure on each slice, the analytic formula of equivalent thickness of multi-throttle-slices was established. Followed is a practical example for the computation of the equivalent thickness of multi-throttle-slices, compared the computed results with that simulated by ANSYS. The results show that the computation method of equivalent thickness of multi-throttle-slices is accurate enough.

Rock burst risk evaluation based on equivalent surrounding rock strength

On-site investigations consistently show that the rock burst inherent to coal seams varies greatly with coal seam thickness.In this study,impact factors related to coal seam thickness and surrounding rock strength were analyzed and a corresponding rock burst risk assessment method was constructed.The model reflects the influence of coal seam thickness on the stress distribution of surrounding rock at the roadway.Based on the roadway excavation range,a stress distribution model of surrounding roadway rock is established and the influence of coal seam thickness on rock burst risk is analyzed accordingly.The proposed rock burst risk assessment method is based on the equivalent surrounding rock strength and coal seam bursting liability.The proposed method was tested in a 3500 mining area to find that it yields rock burst risk assessment results as per coal seam thickness that are in accordance with real-world conditions.The results presented here suggest that coal seam thickness is a crucial factor in effective rock burst risk assessment.

极端生态环境水循环关键参量监测技术研究现状与进展

针对高寒和干旱极端生态环境水循环变化对国家生态安全的重要性,需要开展水循环关键参量监测设备与技术研究。本文重点围绕水循环关键参量野外原位/移动/非接触式、自动、稳定监测等技术难点,开展了一系列监测生态系统水-土-气-冰-雪的关键参量的新技术设备研究。通过构建基于物联网的天地一体化生态系统监测体系,打破行业技术壁垒,促进工程技术、地质学、计算机科学等不同领域的跨学科合作,共同开展极端生态环境水循环关键参量监测技术研究与创新,并将实现对重要生态功能区的大范围、全天候、立体化监测,对推进我国生态文明建设具有重要支撑作用,促进并实现我国生态监测技术的综合应用和发展。

基于水分光谱指数的烟草叶片等效水厚度估测

为及时、准确监测烟草叶片的水分状况,连续2年开展不同基因型烤烟品种的水分胁迫试验,测定烟叶的光谱反射率和叶片等效水厚度(EWT),系统分析350~2500 nm波段范围内任意2个波段组合而成的比值水分指数(SRWI)和归一化水分指数(NDWI),并构建烟草EWT的光谱指数预测模型。结果表明:(1)不同基因型烟草的叶片等效水厚度均随灌水量的减少而降低。(2)不同水分处理的烟叶光谱反射率在可见光波段和近红外波段均发生了规律性变化。(3)筛选出的烟草叶片等效水厚度的光谱敏感波段主要集中在可见光区域的500~600 nm、近红外区域的700~900和1000~1250 nm、短波红外区域的1900~2000 nm,最佳水分光谱指数分别为NDWI(R1920,R1930)、SRWI(R1930,R1920),核心波段为1920、1930 nm。(4)利用水分光谱指数构建的烟草叶片等效水厚度的线性和非线性预测模型,以极限学习机模型(ELM)的精准度和稳定性最佳(P-R2=0.853**,T-R2=0.855**,RMSE=0.004)。表明可利用水分光谱指数NDWI(R1920,R1930)、SRWI(R1930,R1920)结合机器学习模型实现烟草叶片含水量的精准监测。

双层金属板材同速异径蛇形轧制复合变形研究

采用ANSYS Multiphysics/LS-DYNA软件对Q345碳钢/NM400耐磨钢复合板轧制复合过程进行了有限元模拟,并开展蛇形轧制实验,验证了所建立有限元模型的准确性。总结了轧辊直径、错位量、摩擦条件和压下量对复合板变形行为的影响,结果表明,其他工艺参数不变条件下,初始辊径和摩擦条件对复合板平直度的影响较大,初始辊径越大和摩擦系数越小,复合板越平直;错位量和压下量对复合板结合面处等效塑性应变的影响较大,错位量适当增大,压下量越大,复合板结合面处变形更充分;轧辊直径对复合板厚度比影响较大,轧辊直径越大,复合板层厚比越大。其中蛇形轧制错位量的调整可同时实现对板材厚度比、等效塑性应变和弯曲曲率的正向调控,证明了可以通过调整蛇形轧制的错位量获得形性兼优的金属复合板。

建筑用隔汽材料水蒸气透过性能检测技术研究

介绍了建筑用隔汽材料水蒸气当量空气层厚度Sd的检测现状,并对称重法、红外法和电解法进行了对比分析。针对采用称重法检测建筑用隔汽材料水蒸气透过性能的情况,从理论计算、测试精度、结果稳定性、实际操作可行性等方面进行了详细的论证;总结了3种不同检测方法的测试范围及各自的特性。提出了建筑用隔汽材料使用称重法测试水蒸气透过性能的可行性解决方法,即只测试1个称重周期,既可以缩短测试周期,又可以减少干扰因素的影响,且数据稳定性好,也更能代表材料的真实阻湿性能。

耐张塔输电线路等值覆冰厚度的简化预测方法

输电线路覆冰会引发断线倒塔事故,严重影响电网的安全运行,准确监测线路覆冰情况具有重要的工程意义和应用价值。在输电线路综合荷载的静力学模型基础上,提出了两种简化的等值覆冰厚度预测方法。第一种简化方法不需要水平档距和高度差参数,减少了输入参数;第二种简化方法不需要角度传感器,避免角度传感器误差造成的预测性能下降,且减小了系统的硬件成本。结果表明:在大水平档距情况下,第一种简化方法与现有方法的预测性能基本一致;在覆冰前后悬垂角变化不大的情况下,第二种简化方法的预测误差在工程允许范围以内。

采动覆岩与地表下沉关系模型及离层量估算方法

地下开采可能导致地表沉陷、基础设施损毁、土地破坏或地面积水等,进而诱发生态环境恶化。而采空区固体充填和覆岩离层注浆是控制岩层移动,减小采动损害的有效技术手段。传统的覆岩离层注浆往往采用关键层理论、数值模拟、相似材料模型实验和理论分析手段,因涉及的物理力学参数多、边界条件限制等,计算过程复杂,仅能给出离层层位,难以定量确定离层量。开采沉陷研究表明,采动覆岩与地表移动方向指向采空中心,移动边界可以简化为线性边界,基于下沉盆地主断面上地表下沉与任一覆岩下沉的面积相等和煤系地层的层状特征,构建了采动覆岩与地表下沉的关系模型,较好地反映了覆岩与地表下沉随边界角、工作面宽度、开采深度的发展演化规律。采动覆岩与地表下沉比值随埋藏深度增加而增大,反映了采动下沉效应从顶板向覆岩、地表的传递规律;随着宽深比的增加,同一层位岩层下沉与地表下沉比值减小,地表下沉增大;当边界角减小时,地表下沉范围增大,地表下沉值减小。结合钻孔揭示的覆岩结构与组合,可以逐层计算上覆岩层和地表的下沉值,利用两相邻岩层下沉的非一致性,可以确定各岩层间的离层量,通过计算导水裂隙带高度,剔除导水裂隙带内无法形成封闭充填空间的无效离层,进而优选确定出适用于覆岩离层注浆的最大离层及层位,为覆岩离层注浆减沉设计提供了简单、便捷的离层识别方法和离层量定量计算方法。

Neutron distribution and yield produced by 50 MeV/u^(18)O-ion on thick targets

Neutron energy, fluence rate, angular distributions and dose equivalent rate distributions around the thick Be, Cu, An targets bombarded by 50 MeV/u 18O-ion were measured using a threshold detector activation method. At the same time,the neutron yields of 18O-ion and the neutron emission rates in the forward direction were obtained approximately.

Hele-Shaw通道内瓦斯爆炸火焰特性试验研究

为探究甲烷/空气预混气体当量比对Hele-Shaw通道内火焰爆燃特性的影响,自行设计搭建尺寸(长×宽×厚)为950 mm×200 mm×6 mm的透明有机玻璃瓦斯爆炸管道试验平台。通过改变试验平台厚度研究通道间隙对甲烷/空气预混气体火焰结构与传播特性的影响。结果表明,不同的通道厚度和当量比对火焰锋面结构和火焰传播动态特性有显著影响。当通道厚度为6 mm时,最大火焰传播速度发生在化学当量比下,为12.84 m/s,且在该工况下火焰最先到通道末端,时间为518.57 ms。当量比为0.8的贫燃状态时,在火焰不稳定性的作用下,火焰传播后期出现二次振荡现象及手指形的火焰锋面。随着通道厚度的减小,火焰到达通道末端的时间逐渐变长,对火焰整体传播速度有明显的抑制作用。

不同网格间距的小剪跨比网格剪力墙抗震性能研究

为研究网格间距对网格剪力墙抗震性能的影响,对两个竖肢中心距不同的小剪跨比网格剪力墙进行了拟静力试验及有限元分析。结果表明:横肢中心距相同、竖肢中心距分别为200 mm及300 mm的网格剪力墙破坏模式不同,竖肢中心距为200 mm的网格剪力墙下部和墙底角部混凝土破坏,破坏模式为剪压破坏;竖肢中心距为300 mm的网格剪力墙沿对角线主斜裂缝错动并产生滑移,破坏模式为剪拉破坏。两个试件的极限位移角均在1/100左右,竖肢中心距为300 mm的网格剪力墙刚度和承载力略大。有限元模拟结果与试验吻合良好,验证了模拟方法的有效性。提出了适用于不同间距网格墙的等效厚度计算方法,网格剪力墙可等效为实体剪力墙计算刚度和承载力。

断层对煤层瓦斯封闭性定量方法研究

断层对煤层瓦斯具有封闭和通道的双重作用,这主要取决于断层的封闭能力。针对断层对瓦斯封闭能力定量化表征方法,结合断裂带结构发育多元学说,分析了断裂带结构参数(两盘煤层对接系数、泥质含量、紧闭系数等)对断层封闭性的影响规律;考虑了诱导裂隙带宽度与渗透率的相关性,提出了一个断裂带泥岩等效厚度的计算公式和一种渗透率补偿算法,以此为基础,依据低速渗流理论,实现了断层极限封闭压力计算,继而对断层封闭性进行量化表征。研究结果表明:(1)断层封闭性主要受控于断裂带内部结构与断层端面受力状态,考虑顶底板围岩封闭能力和煤储层压力,利用断裂带结构参数和断层封闭压力可对断层封闭性进行综合定量表征;(2)诱导裂隙带煤层渗透率与距端面距离负相关,离端面越远,综合渗透率越低,最后趋近于原始煤层渗透率;(3)等效泥岩厚度越大,断层极限封闭压力越高,断层封闭性越好;(4)沁水盆地郑庄-樊庄区块的寺头断层封闭性计算结果显示,该断层封闭压力高于4.67 MPa,大于储层压力3.83 MPa。然而,该断层走向上的封闭能力存在差异,北东向断层端面封闭性好,西南向断层端面封闭能力则相对较差。研究成果对于科学判识断层的瓦斯封闭能力,指导井下煤与瓦斯突出预测及地面煤层气高效开发具有重要技术支撑作用。

水中总α放射性测量的超铀α核素探测效率研究

乏燃料处理厂运行、退役可能释放超铀核素到环境中,其环境水体和废水中总α放射性监测是环境监管重点工作。超铀α核素发出α射线能量和分支比不同,造成其探测效率有较大差异,准确分析其探测效率有利于提高测量准确性。通过蒙特卡洛模拟和实验装置模型,模拟20个不同质量厚度的13个超铀α核素的探测效率,并计算其计数率、探测效率等效因子、活度比计数率,进一步分析这些量与质量厚度的关系及对测量结果的影响。研究表明:当用^(241)Am作标准源,需要用探测效率等效因子、分支比、比例进行探测效率修正;当质量厚度小于2.548 mg/cm^(2)时,探测效率等效因子为0.72~1.00;当质量厚度大于饱和厚度时,探测效率的倒数与质量厚度呈线性关系,可以更优刻度探测效率;饱和厚度与α射线平均能量呈线性关系,可以最优进行质量厚度源制备。

水中总α、β放射性测量中探测效率等效因子相关性探讨

研究水中总放射性测量探测效率等效因子相关性。通过蒙特卡洛模拟计算和试验测量比较8个不同质量厚度40K、241Am源探测效率,验证实验测量装置模拟模型。模拟20个不同质量厚度、3个不同半径辐射源的6个α和β核素探测效率,计算其探测效率等效因子,进一步分析不同质量厚度,不同半径辐射源,不同能量的α、β核素探测效率等效因子相对偏差。40K作标准源,β核素辐射源半径不同,引起的探测效率等效因子相对偏差小于1.5%;241Am作标准源,α核素辐射源半径不同,引起的探测效率等效因子相对偏差小于8.05%,当质量厚度等于11.21 mg/cm^(2),辐射源半径不同引起的探测效率等效因子相对偏差小于3.08%。水中总α、β放射性测量,辐射源半径对α、β探测效率等效因子影响小于10%;日常水中总放射性测量,可以不考虑辐射源半径不同引起的探测效率等效因子修正,其结果能够满足相关标准要求。

基于蒙特卡罗方法的钢渣混凝土的中子屏蔽性能模拟

基于蒙特卡罗方法,采用FLUKA软件建立了中子源散射球壳和质子源入射水靶球壳数值模型,分析了不同厚度钢渣混凝土对不同能量等级和不同屏蔽角度中子射线的屏蔽能力,并与普通混凝土进行了对比。结果表明:随着屏蔽厚度的增加,混凝土对中子射线的屏蔽能力不断提升;混凝土对慢中子射线和中能中子射线的屏蔽效果优于快中子射线;钢渣混凝土对中子射线的屏蔽效果优于普通混凝土;屏蔽角度越大,使关注点剂量当量率满足规范要求的混凝土屏蔽厚度越小;用钢渣混凝土取代普通混凝土可显著减小材料的屏蔽厚度。