Frequency in Middle of Magnon Band Gap in a Layered Ferromagnetic Superlattice

The frequency in middle of magnon energy band in a five-layer ferromagnetic superlattice is studied by using the linear spin-wave approach and Green＇s function technique. It is found that four energy gaps and corresponding four frequencie in middle of energy gaps exist in the magnon band along Kx direction perpendicular to the superlattice plane. The spin quantum numbers and the interlayer exchange couplings all affect the four frequencies in middle of the energy gaps. When all interlayer exchange couplings are same, the effect of spin quantum numbers on the frequency wg1 in middle of the energy gap Δw12 is complicated, and the frequency wg1 depends on the match of spin quantum numbers in each layer. Meanwhile, the frequencies wg2, wg3, and wg4 in middle of other energy gaps increase monotonously with increasing spin quantum numbers. When the spin quantum numbers in each layer are same, the frequencies wg1, wg2, wg3, and wg4 all increase monotonously with increasing interlayer exchange couplings.

Research on Thin Layer Structure Identification and Sedimentary Facies of Middle and Deep Layers Based on Reflection Coefficient Inversion—By Taking Dongying Formation of CFD Oilfield in Bohai Offshore as an Example

The sand layer B of Dongying Formation of CFD oilfield in Bohai offshore belongs to the middle deep layer of buried hill overlap deposit. Its reservoir distribution has the characteristics of large burial depth, thin thickness and rapidly lateral change. Because of low resolution of seismic data and overlying sand layer. It is difficult to identify and interpret the structure of sand layer accurately. The uncertainty of structure and reservoir restricts the fine development of B sand layer. In order to identify the top surface of reservoir effectively. The seismic data are processed by using the reflection coefficient inversion method. The results show that the inversion resolution of reflection coefficient is significantly higher than that of original data. The top surface of sand layer B and its overlying sand layer can be well identified and traced. Carrying out structural interpretation of B sand layer based on reflection coefficient inversion data and the microstructure and the formation tip extinction point are implemented. Based on the constraint of new interpretation level, the sedimentary facies plane distribution of B sand layer is described and make prediction of dominant reservoir development area in detail combining with sedimentary paleogeomorphology, along layer attribute section and limited drilling data. The research shows that the study area is mainly from the northwest material sources, the slope belt in the northwest is close to the lake shoreline with a gentle slope and shallow water depositional environment, which is located on the main transport and deposition channels. The shallow water gentle slope landform is suitable for forming large-area sand bar deposition, mainly composed of underwater distributary channel and debouch bars facies, which is the dominant reservoir development area. The research conclusion guides the deployment and implementation of the development well location effectively.

Fault characteristics and control on hydrocarbon accumulation of middle-shallow layers in the slope zone of Mahu sag, Junggar Basin, NW China

The development, evolution and formation mechanism of faults and their control on the migration and accumulation of Mesozoic oil and gas in the middle-shallow layers of the slope zone of Mahu sag were studied by the interpretation of seismic and drilling data. Two types of faults, normal and strike-slip, are developed in the middle-shallow layers of the slope zone of the Mahu sag and they are mostly active in the Yanshanian period. They are divided into four grade faults: The grade I strike-slip faults with NWW to near EW direction are related to the left-lateral transpressive fault zones in the northwest of Junggar Basin since the end of the Triassic. The grade II faults with NE to NNE direction are the normal faults located at the junction of the fault zone and the slope zone, and their formation is related to the extension at the top of the nose-like structures in the fault zone. The grade III faults, which are also the normal faults, are the result of the extension at the top of the lower uplifts in the slope zone and differential compaction. The grade IV faults with NE direction are normal faults, which may be related to the extension environment at the tip of the lower uplifts. Faults not only are the channel for the vertical migration of oil and gas, but also control the oil-gas accumulation. There are two types of oil-gas reservoirs in the middle-shallow layers of slope zone of Mahu sag: fault block reservoirs and fault-lithologic reservoirs. They have large traps and promising exploration potential.

Advances in Researches on the Middle and Upper Atmosphere in 2008-2010

This paper summarizes the results of the researches on the middle and upper atmosphere obtained by Chinese scientists in 2008-2010.The focuses are specifically placed on the researches being associated with ground-based observation capability development,dynamical processes,the property of atmospheric circulation and the chemistry-climate coupling of the middle atmospheric layers.

Advances in the Researches of the Middle and Upper Atmosphere in China

In this report we summarize the research results by Chinese scientists in 2018–2020.The focuses are placed on the researches of the middle and upper atmosphere,specifically the researches on atmospheric structure and composition,climate and chemistry-climate coupling and climate modelling,dynamics in particular those inducing the coupling of the atmospheric layers.

Analysis of the Characteristics of the Low-level Jets in the Middle Reaches of the Yangtze River during the Mei-yu Season

Here,we analyze the characteristics and the formation mechanisms of low-level jets(LLJs)in the middle reaches of the Yangtze River during the 2010 mei-yu season using Wuhan station radiosonde data and the fifth generation of the European Centre for Medium-Range Weather Forecasts(ERA5)reanalysis dataset.Our results show that the vertical structure of LLJs is characterized by a predominance of boundary layer jets(BLJs)concentrated at heights of 900-1200 m.The BLJs occur most frequently at 2300 LST(LST=UTC+8 hours)but are strongest at 0200 LST,with composite wind velocities>14 m s^(-1).Synoptic-system-related LLJs(SLLJs)occur most frequently at 0800 LST but are strongest at 1100LST,with composite wind velocities>12 m s^(-1).Both BLJs and SLLJs are characterized by a southwesterly wind direction,although the wind direction of SLLJs is more westerly,and northeasterly SLLJs occur more frequently than northeasterly BLJs.When Wuhan is south of the mei-yu front,the westward extension of the northwest Pacific subtropical high intensifies,and the low-pressure system in the eastern Tibetan Plateau strengthens,favoring the formation of LLJs,which are closely related to precipitation.The wind speeds on rainstorm days are greater than those on LLJ days.Our analysis of four typical heavy precipitation events shows the presence of LLJs at the center of the precipitation and on its southern side before the onset of heavy precipitation.BLJs were shown to develop earlier than SLLJs.

Analysis of Seismic Activity in the Middle Part of the North-South Seismic Belt——Joint Study on Deep Seismic Sounding Profile and Seismicity Parameters

Using the rich deep seismic sounding data recorded in the middle part of the NorthSouth Seismic Belt in China,the horizontal and vertical profiles are constructed to obtain the seismic velocity structure,analyze the seismic distribution and calculate the seismic energy and the thickness of the seismogenic layer at the same time.On this basis,the seismicity parameters are calculated using the earthquake catalogue of the study area for the past 40 years,and the relationship between the b-value distribution and the velocity structure is analyzed.The results show an uneven b-value distribution in the study area and a segmented feature along the Longmenshan fault zone.Most of the earthquakes occur in the transition zone anomalies from the positive to the negative.In addition,the thickness of the crust drops from ~60 km to ~48 km from the Southeastern to the Northeastern Qinghai-Tibetan Plateau,but the thickness of the seismogenic layer increases gradually.It is speculated that the crustal composition of the Northeastern margin contains more felsic materials and has relatively stronger seismic activities than the Southeastern Qinghai-Tibetan Plateau,possibly associated with the subduction and compression of the Indian Ocean Plate.

台内滩型薄层状白云岩储集层特征及主控因素——以四川盆地高石梯—磨溪地区中二叠统栖霞组为例

通过对四川盆地高石梯—磨溪地区中二叠统栖霞组台内滩分布及白云岩储集层特征的研究,分析储集层发育控制因素,建立“台内滩型薄层状白云岩储集层”成储模式。研究表明:栖霞组自下而上为海退旋回,栖一段发育低能开阔海亚相,栖二段海平面下降演化为台内滩及滩间海,台内滩主要分布于栖二段两个次级变浅旋回近顶部。栖霞组主要的储集层岩性为薄层状裂缝-孔洞型白云岩,其次为孔洞型白云岩,缝洞中常见鞍状白云石半充填,晶间孔、残余溶蚀孔洞叠加裂缝形成了有效的孔渗网络。基于沉积及成岩特征耦合分析,系统建立了“沉积前微古地貌控滩、沉积期滩体控制白云岩展布、准同生白云石化有利于孔渗网格保存,晚期热液作用有效改善储集物性”的成储模式。栖霞组沉积前的“一级高带”微古地貌控制栖二段沉积期高石梯地区台内滩的大面积发育;滩相是早期云化的基础条件,台内滩与白云岩储集层分布范围的吻合程度较高;滩相颗粒灰岩受两期白云石化叠加改造,准同生期白云石化有助于原生孔隙和次生溶孔保存,埋藏期热液沿峨眉山玄武岩事件伴生的裂缝进入早期白云岩体,使其重结晶为中—粗晶白云岩,晶间孔叠加顺缝热液溶蚀的残余孔洞,形成了台内滩型薄层状优质白云岩储集层。该成储模式的建立可为四川盆地二叠系气藏的可持续开发提供地质理论支撑。

Acute macular neuroretinopathy following COVID-19 infection:Three case reports

BACKGROUND During the Coronavirus disease 2019(COVID-19)pandemic,a notable increase in acute macular neuroretinopathy(AMN)cases was observed.This study aimed to investigate the potential association between AMN and COVID-19 by examining 3 cases in China.CASE SUMMARY The first case involved a 30-year-old man who presented with progressive vision loss following a COVID-19 infection.Optical coherence tomography(OCT)and near-infrared imaging identified hallmark AMN lesions,hyperreflective disruptions within the outer plexiform layer,and hyporeflective anomalies in the ellipsoid zone,leading to an AMN diagnosis.Despite partial visual recovery,OCT angiography(OCTA)revealed persistent microvascular changes,specifically a decreased vascular density in the deep capillary plexus.The second case was a 24-year-old woman who experienced blurred vision and exhibited bilateral cottonwool spots on fundus examination post-COVID-19.Imaging confirmed the presence of AMN along with paracentral acute middle maculopathy(PAMM).Follow-up OCTA found a progressive reduction in vascular density,indicating ongoing microvascular compromise.The third case was a 28-year-old woman who reported sensations of occlusion in her right eye following a COVID-19 infection.Imaging confirmed both AMN and PAMM,revealing similar decreases of microvascular density on OCTA despite a significant improvement in visual acuity.We noted that all 3 patients had received the COVID-19 vaccine prior to the appearance of symptoms.CONCLUSION The findings highlight the diagnostic utility of advanced ocular imaging in detecting AMN in COVID-19 patients and the importance of comprehensive eye examinations.

板桥地区中浅层辫状河沉积储层预测研究

板南中浅层馆陶组油藏具有油层单一、底水发育的特点,准确刻画油层的位置、油层上下隔夹层的分布是有效开发的关键。通过开展沉积储层研究,认为板南馆陶组为辫状河沉积体系,主要发育心滩、辫状水道、水道间、泛滥平原泥4个微相。储层属高孔高渗储层,非均质性较强,油层分布比较稳定。分析认为常规反演方法分辨率较低,无法有效识别单砂体;而地震波形指示反演在单砂体的识别能力上具有明显的优势,可以满足水平井部署的需要。以储层反演成果为基础,完成油藏工程方案及实钻动态跟踪,并取得良好效果,证明了储层反演方法的可靠性。

辽河盆地西部凹陷中深层超压体系成因机制研究

辽河盆地西部凹陷中深层发育明显超压,明确其超压的分布和形成机制对该地区中深层油气勘探具有重要意义。基于实测地层压力、测井曲线组合、超压成因判识图版及盆地模拟等方法,针对西部凹陷中深层超压发育特征、成因机制及超压对成藏的控制作用进行了研究。结果表明,西部凹陷整体发育超压型、常压型、低压型3类温压系统,超压主要发育在2500~4000 m的中深层,超压成因以欠压实作用为主。在中段冷家—雷家地区沙三段地层超压除欠压实作用贡献外,局部伴有生烃增压、成岩作用和构造挤压的混合贡献,北段因遭受过强烈的抬升剥蚀作用,表现为异常低压为主。采用盆地模拟手段对超压成因贡献量进行评价,其压力演化存在3期:第1期以构造沉降作用导致的欠压实作用为主;第2期由于地层抬升泄压,欠压实和流体膨胀作用经历短暂停止;第3期烃源岩到达生烃高峰,生烃增压作用逐渐增强且流体膨胀增压可达5 MPa。

长江中下游岸坡单元体的水力侵蚀室内试验研究

水作用下长江中下游岸坡正在面临严峻的崩岸破坏。为探究岸坡土体的水力侵蚀特性,进行单元体单面浸水湿化-崩解试验与侧向冲刷水毁室内试验,通过分析冲刷沟形态、测量单元体质量、探究侧向冲刷深度和高度变化规律,研究根系和格栅植被面层对单元体侵蚀破坏的影响,分析运用乔木根系联合格栅植被面层对岸坡进行防冲的可行性。试验结果表明:湿化-崩解与侧向冲刷二者共同作用,引起和加剧岸坡土体的淘蚀破坏。随着水深、流速及冲刷时间的增加,单元体侧向冲刷深度与冲刷高度一直增加;在本实验较小的单元体尺寸下,较粗的乔木模拟根系对于减小单元体冲蚀破坏程度的作用有限,其根土间隙优先流效应在一定程度上反而增加侧向冲刷深度;根系对黏性土的牵拉锚固作用明显强于粉土质砂,能够延缓上部土体的崩塌;设置格栅植被面层后,可有效减小单元体侧向冲刷深度,抗冲效果显著,研究结果可为生态护岸技术研发和应用提供借鉴。

基于深度流形蒸馏网络的高光谱遥感图像场景分类方法

当前场景分类任务大多面向高分辨率遥感图像,由于缺乏光谱信息限制了它的场景鉴别能力,而高光谱遥感图像具有“空谱合一”的特性,在场景分类问题上具有独特优势。针对高光谱遥感图像中地物分布复杂,以及高光谱图像中维度高、存在冗余等问题,本文提出一种高光谱场景分类流形蒸馏网络(hyperspectral scene classification manifold distillation network,HSCMDNet),有效提高了分类性能。对于遥感图像地物分布复杂问题,HSCMDNet模型使用基于移位窗口的层次化视觉Transformer(hierarchical vision transformer using shifted windows,SwinT)作为教师网络来充分挖掘高光谱图像的长距离依赖信息,捕获不同波段之间的关系。在此基础上,在教师网络与ResNet-18学生网络之间设计流形蒸馏损失,通过在流形空间中匹配学生和教师的中间层输出特征实现教师模型的知识更有效地向轻量化学生模型转移,缓解了高光谱图像中维数高导致的高计算复杂性问题。在欧比特高光谱图像场景分类数据集(Orbita hyperspectral image scene classification dataset,OHID-SC)及天宫二号遥感图像自然场景分类数据集(natural scene classification with Tiangong-2 remotely sensed imagery,NaSC-TG2)上,所提出的HSCMDNet网络的最佳分类精度分别达到了93.60%和94.55%。

中深层地热田开发利用技术研究进展

地热能是重要的可再生能源,是我国“十四五”期间重点发展的可再生能源之一。我国地热能直接利用量连续多年保持世界第一,但中深层地热田开发利用技术与国外先进水平尚有差距。当前全球地热初创公司快速增长,地热资源开发力度持续加大,地热能利用场景多样化,地热发电装机容量稳步增长,开发利用技术取得较大进展。具体表现为4个方面:(1)中深层闭式换热系统设计技术逐渐成熟;(2)EGS技术取得历史性突破,应用潜力巨大;(3)多国重视含水层储热在弥补能源供需不平衡上的作用,加快推进含水层储热场址选择、热回收率及风险分析等方面的研究;(4)回灌成为中深层水热型热储开发的通用做法,回灌数值模拟及方案设计、防腐蚀、防结垢、防堵塞等技术进步有效延长了地热田的生命周期。“双碳”背景下,我国应将关键技术研发作为发展新质生产力的主要突破口,快速升级中深层地热田开发利用技术,有效提升地热项目经济性,实现地热利用规模持续增长。

中下地壳切向分层流变的结果:喜马拉雅东段雅拉香波片麻岩穹隆

大陆中、下地壳切向(近水平)分层固态流动变形是地壳物质流动的重要形式之一,也是片麻岩穹隆的重要形成机制。雅拉香波穹隆位于特提斯喜马拉雅构造带的最东段,出露不同变质级别和时代的岩石地层,发育强烈的韧性剪切变形以及多期岩浆事件,是研究造山过程中构造变形和岩浆历史的天然实验室。本文以该穹隆为研究对象,进行了详细的野外构造解析和显微观察等工作,总结出以下三个特点:(1)雅拉香波穹隆内不同构造层次的岩石经历了相同的构造体制和不同变形条件改造:从浅部到深部,变形温度逐渐递增,由390℃到600℃;差应力逐渐减小,从24.58MPa减少至8.72MPa;应变速率逐渐加快,从1.27×10^(-13)~1.28×10^(-13)/s增加到5.19×10^(-11)~5.21×10^(-11)/s。以上体现了地壳活动带强烈的分层流变特点。(2)结合前人研究划分了穹隆变形的三个期次(D_(1)、D_(2)和D_(3)),其中D_(1)表现为上盘向南的剪切方向,D_(2)则表现为上盘向北的剪切方向。进一步,将主要变形期次D_(2)进一步划分为两个阶段,早期主要是以单剪为主导的剪切作用类型,而晚期则是以纯剪为主导的剪切作用类型。(3)根据D_(2)面理和线理的产状分布特点,可以得出,深部岩石线理的倾伏角近水平,而浅层次岩石的线理倾伏角近竖直。基于以上研究表明,雅拉香波穹隆各部分岩石均遭受了不同程度的剪切改造,不同构造层次的岩石具有几何学上的一致性以及运动学上的解耦,体现了穹隆发育过程中运动方向上的转变。结合穹隆各部位线理的倾伏角的变化规律,本文认为雅拉香波穹隆记录了中下地壳分层流动的过程,穹隆的形成主要受中下地壳近水平切向流动控制,辅以垂向流动的改造。

公意机制:国家治理中“中间层”的新实践形式

在中国,国家在乡村社会的治理通常需要一个“中间层”,纵向联结农民,横向组织社会。这个“中间层”存在多种实践形式,除了常见的代理机制外,成都市公共服务资金制度的运行过程展示出一种新形式,即公意机制。公意机制是在国家资源下乡的背景下,农民通过议事协商等方式形成的公共意志及其运行过程,是国家外部建构与村庄内部生长联动的产物。与代理机制的精英化路线不同,公意机制运用国家的资源输入直接动员农民,将分散的农民个体转变为组织化的行动集体,走的是群众化路线。公意本身就是一种公共性力量,能够释放出强大的治理效能,能够弥补代理机制本身附带的代理失效问题,为理解新时代国家与社会的关系提供了新思路。

社会再组织化与村级治理有效——基于湖北“雁子工作室”治理经验的实证分析

村级治理有效不仅需要基层组织发挥示范引领作用,还需要将农民组织起来,发挥村庄内生性禀赋优势。基层治理转型期,自上而下的治理压力和细碎繁琐的治理事务对村干部精力和注意力的挤占,弱化了村干部组织农民参与治理的能力。对湖北恩施“雁子工作室”治理创新的田野调查发现,在对农民进行行政性的整合基础上,通过再组织化机制实现治理对农民的社会性吸纳,是治理有效的重要路径。“雁子工作室”通过细化治理单元、再造组织载体、优化权责分配重塑农民参与治理的组织结构,健全农民参与治理的制度保障和路径支持。再组织化的核心是激活基层治理的“社会性”属性,通过治理结构的社会性嵌入与调整、治理主体的社会性动员与吸纳、内生性社会资本的激活与整合,再组织化再造了国家与社会互动的“中间结构”,在提高国家与社会的互动效率和社会的自主治理能力基础上,推动村级治理有效。

基于新课标的初中英语分层阅读教学路径探究

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