NORMALIZED SOLUTIONS FOR THE GENERAL KIRCHHOFF TYPE EQUATIONS

In the present paper,we prove the existence,non-existence and multiplicity of positive normalized solutions(λ_(c),u_(c))∈R×H^(1)(R^(N))to the general Kirchhoff problem-M■,satisfying the normalization constraint f_(R)^N u^2dx=c,where M∈C([0,∞))is a given function satisfying some suitable assumptions.Our argument is not by the classical variational method,but by a global branch approach developed by Jeanjean et al.[J Math Pures Appl,2024,183:44–75]and a direct correspondence,so we can handle in a unified way the nonlinearities g(s),which are either mass subcritical,mass critical or mass supercritical.

Normalized glandular dose coefficients for digital breast tomosynthesis using detailed Chinese breast models

The rise in breast cancer diagnoses among Chinese women has necessitated the use of X-ray breast screening,which carries a radiation risk.This study aimed to provide a dosimetry protocol for the Chinese female population to replace the traditional standard that utilizes simplified breast models,for the accurate estimation of the mean glandular dose of a patient undergoing digital breast tomosynthesis(DBT).The first set of detailed Chinese female breast models and representative breast parameters was constructed.Considering backscatter radiation and computational efficiency,we improved the combination of these models and the Chinese reference adult female whole-body voxel phantom.Image acquisition for four commercial DBT systems that are widely employed in China was simulated using the Monte Carlo method to obtain the normalized glandular dose coefficients of DBT(D_(gN)^(DBT))and the glandular depth dose(D_(g)^(dep)(z))for different breast characteristics and X-ray spectra.We calculated a series of D_(gN)^(DBT) values for breasts with different percentage mass glandularities(5%,25%,50%,75%,and 100%)and compressed breast thicknesses(2,3,4,5,6,and 7 cm)at various tube potentials(25,28,30,32,35,and 49 kV)and target/filter combinations(W/Rh,W/Al,Mo/Mo,Rh/Rh,and Rh/Ag).The parameter dependence of the breast characteristics and beam conditions on D_(gN)^(DBT) in detailed breast models was investigated.The D_(gN)^(DBT) results were 14.6-51.0%lower than those of the traditional dosimetry standard in China.The difference in D_(gN)^(DBT) was mainly due to a decrease in the depth of the main energy deposition area caused by the glandular distribution along the depth direction.The results obtained in this study may be used to improve breast dosimetry in China and provide more detailed information on risk assessment during DBT.

MULTIPLICITY OF NORMALIZED SOLUTIONS FOR THE FRACTIONAL SCHR?DINGER-POISSON SYSTEM WITH DOUBLY CRITICAL GROWTH

In this paper,we are concerned with solutions to the fractional Schrodinger-Poisson system■ with prescribed mass ∫_(R^(3))|u|^(2)dx=a^(2),where a> 0 is a prescribed number,μ> 0 is a paremeter,s ∈(0,1),2 <q <2_(s)^(*),and 2_(s)^(*)=6/(3-2s) is the fractional critical Sobolev exponent.In the L2-subcritical case,we show the existence of multiple normalized solutions by using the genus theory and the truncation technique;in the L^(2)-supercritical case,we obtain a couple of normalized solutions by developing a fiber map.Under both cases,to recover the loss of compactness of the energy functional caused by the doubly critical growth,we need to adopt the concentration-compactness principle.Our results complement and improve upon some existing studies on the fractional Schrodinger-Poisson system with a nonlocal critical term.

Normalized Ground State Solutions of Nonlinear Choquard Equations with Nonconstant Potential

In this paper,we mainly focus on the following Choquard equation-{△u-V(x)(I_(a*)|u|^(p))|u|^(p-2)u=λu,x∈R^(N),u∈H^(1)(R^(N))where N≥1,λ∈R will arise as a Lagrange multiplier,0<a<N and N+a/N<p<N+a+2/N Under appropriate hypotheses on V(x),we prove that the above Choquard equation has a normalized ground state solution by utilizing variational methods.

Assessment of vegetation cover changes and the contributing factors in the Al-Ahsa Oasis using Normalized Difference Vegetation Index(NDVI)

The abandonment of date palm grove of the former Al-Ahsa Oasis in the eastern region of Saudi Arabia has resulted in the conversion of delicate agricultural area into urban area.The current state of the oasis is influenced by both expansion and degradation factors.Therefore,it is important to study the spatiotemporal variation of vegetation cover for the sustainable management of oasis resources.This study used Landsat satellite images in 1987,2002,and 2021 to monitor the spatiotemporal variation of vegetation cover in the Al-Ahsa Oasis,applied multi-temporal Normalized Difference Vegetation Index(NDVI)data spanning from 1987 to 2021 to assess environmental and spatiotemporal variations that have occurred in the Al-Ahsa Oasis,and investigated the factors influencing these variation.This study reveals that there is a significant improvement in the ecological environment of the oasis during 1987–2021,with increase of NDVI values being higher than 0.10.In 2021,the highest NDVI value is generally above 0.70,while the lowest value remains largely unchanged.However,there is a remarkable increase in NDVI values between 0.20 and 0.30.The area of low NDVI values(0.00–0.20)has remained almost stable,but the region with high NDVI values(above 0.70)expands during 1987–2021.Furthermore,this study finds that in 1987–2002,the increase of vegetation cover is most notable in the northern region of the study area,whereas from 2002 to 2021,the increase of vegetation cover is mainly concentrated in the northern and southern regions of the study area.From 1987 to 2021,NDVI values exhibit the most pronounced variation,with a significant increase in the“green”zone(characterized by NDVI values exceeding 0.40),indicating a substantial enhancement in the ecological environment of the oasis.The NDVI classification is validated through 50 ground validation points in the study area,demonstrating a mean accuracy of 92.00%in the detection of vegetation cover.In general,both the user’s and producer’s accuracies of NDVI classification are extremely high in 1987,2002,and 2021.Finally,this study suggests that environmental authorities should strengthen their overall forestry project arrangements to combat sand encroachment and enhance the ecological environment of the Al-Ahsa Oasis.

Normalized fatigue properties of asphalt mixture at various temperatures

This study normalized the mixture's fatigue behavior at various temperatures,and the strength and fatigue tests of the mixture were conducted.The stress state of the asphalt mixture includes direct tensile,uniaxial compression,and indirect tensile.The Desai yield surface and fatigue path were proposed.And a normalized fatigue characteristics model of the mixture was established.The following conclusions were obtained.With the increases in the loading rate,the strength of the asphalt mixture increased.As the temperature increases,the strength of the mixture is reduced.At various temperatures and rates,the strength forms a closed curved surface.The Desai strength yield surface was established,which forms a closed curved surface.When the loading rate and temperature are below a certain critical line,the asphalt mixture will not undergo strength damage.At a fixed stress state,the fatigue damage path of the mixture was determined.The stress ratio was determined considering the influence of the loading rate.In this way,a normalized model can be described to express the asphalt mixture fatigue properties at various temperatures and stress levels.For the asphalt mixture in an indirect tensile state,the normalized fatigue equation parameter is 4.09.This model is more suitable for reflecting the viscous-elastic behavior of the mixtures than the fatigue equation determined by the notional stress ratio.

THE EXISTENCE AND STABILITY OF NORMALIZED SOLUTIONS FOR A BI-HARMONIC NONLINEAR SCHR?DINGER EQUATION WITH MIXED DISPERSION

In this paper,we study the ground state standing wave solutions for the focusing bi-harmonic nonlinear Schrodinger equation with aμ-Laplacian term(BNLS).Such BNLS models the propagation of intense laser beams in a bulk medium with a second-order dispersion term.Denoting by Qpthe ground state for the BNLS withμ=0,we prove that in the mass-subcritical regime p∈(1,1+8/d),there exist orbit ally stable ground state solutions for the BNLS when p∈(-λ0,∞)for someλ0=λ0(p,d,‖Qp‖L2)>0.Moreover,in the mass-critical case p=1+8/d,we prove the orbital stability on a certain mass level below‖Q*‖L2,provided thatμ∈(-λ1,0),where■and Q*=Q1+8/d.The proofs are mainly based on the profile decomposition and a sharp Gagliardo-Nirenberg type inequality.Our treatment allows us to fill the gap concerning the existence of the ground states for the BNLS when p is negative and p∈(1,1+8/d].

THE EXISTENCE OF GROUND STATE NORMALIZED SOLUTIONS FOR CHERN-SIMONS-SCHRODINGER SYSTEMS

In this paper,we study normalized solutions of the Chern-Simons-Schrödinger system with general nonlinearity and a potential in H^(1)(ℝ^(2)).When the nonlinearity satisfies some general 3-superlinear conditions,we obtain the existence of ground state normalized solutions by using the minimax procedure proposed by Jeanjean in[L.Jeanjean,Existence of solutions with prescribed norm for semilinear elliptic equations,Nonlinear Anal.(1997)].

建构高质量的教师教育实践课程体系

教育实践课程作为教师教育的重要组成部分,承担着重要的育人使命。梳理新中国成立后教育实践课程的发展历程发现,教育实践课程经历了学苏中改造、恢复中改革、发展中转型等三个阶段。教育实践课程的开设有助于完善师范生的知识结构、提升师范生的教学技能、塑造师范生的情怀品质。未来应从教师教育信念、实践课程资源、实践课程师资队伍与课程评价体系四个向度构建高质量的教师教育实践课程体系。

1991~2020年中国地面气候值数据集研制

基于国家气象信息中心归档的中国地面观测数据,研制了1991~2020年中国地面气候值数据集。数据集研制期间,对1991年以来的地面台站观测数据集元数据进行了系统的质量检查和核实订正。在基于站址迁移信息对所有要素进行了分段处理基础上,基于非均一性检验结果完成了气温序列的分段处理。依据人工、自动观测调整信息完成了能见度观测数据的分段处理,提供了一套与当前能见度观测方式一致、代表性更好的气候背景场。采用傅里叶级数理论对气温、降水累年日值序列进行了谐波处理,在体现气象变量季节性转换的同时,避免了日与日之间的异常突变特征,具有更好的气候代表性。最终建立的1991~2020年中国地面气候值数据集提供了中国2438个站点的气温、降水、气压、风向风速、相对湿度、水汽压、云、天气现象、能见度、蒸发、积雪、地温、冻土、日照共14个要素的气候背景信息,为天气气候业务提供了数据支撑。

基于Sentinel-2的青铜峡灌区水稻和玉米种植分布早期识别

及时准确地掌握灌区内作物种植分布对于灌溉水资源高效配置、农田精准管理具有重要指导意义。以宁夏青铜峡灌区为研究对象,利用多时相Sentinel-2卫星数据,通过水稻和玉米早期特征分析,提取关键的“水淹”信号和“植被”信号,构建时序归一化差异水体指数(MNDWI)和归一化植被指数(NDVI)特征值数据集,并通过样本分析关键特征阈值,构建水稻和玉米早期种植分布决策树模型,提取2022年宁夏青铜峡灌区水稻和玉米种植的空间分布。结果表明(:1)玉米和水稻苗期的后半段5月15—31日,水淹信号和植被信号是区分二者关键时期。(2)基于早期作物物候特征的方法,在5月16—31日获取的水稻和玉米图像制图精度高于90%,用户精度超过91%,总体精度超过90%,Kappa系数高于0.88,明显高于同时期随机森林方法的分类精度。(3)本研究提出的方法在早期水稻和玉米种植分布提取方面具有较强的适用性,并且能够在时空尺度上以较少的实地样本进行延展,同时在时间上也更有优势。因此,该方法为青铜峡灌区水稻和玉米种植分布早期调查提供了重要的方法支撑。

中华民族共同体学学科的时代价值与建设路径

加强中华民族共同体学学科建设,是铸牢中华民族共同体意识从单项突破迈向系统推进,完善宣传教育常态化机制,构建课堂教学、社会实践、主题教育等多位一体教育平台的必要举措。从政治、经济、文化和社会等维度来看,中华民族共同体学学科建设有助于民族事务治理现代化、推动各民族共同繁荣、加强中华民族共有精神家园建设、促进民族团结进步创建,具有防范化解民族领域风险隐患,维护国家统一、民族团结稳定大局,维护民族领域意识形态安全等时代价值。针对现阶段中华民族共同体学学科建设相对滞后,与推进新时代党的民族工作高质量发展的要求还有较大差距的情况,需要加强学术体系、人才培养体系、社会服务体系等方面的建设,使之与推进新时代党的民族工作高质量发展、实现中华民族伟大复兴的历史任务相适应。

教育家精神融入师范院校人才培养的价值、挑战与路径

习近平总书记提出的教育家精神在师范院校人才培养中具有重要的价值和意义,师范院校人才培养能够与其自洽融合,它是师范教育体系构建的精神支柱,能够促进师范生专业素养与职业道德的提升。但师范院校在培养师范生教育家精神方面也面临各种困境,需要师范院校主动作为克服一系列挑战,在理想信念的内化、道德情操的塑造、育人智慧的授予、躬耕态度的引导、仁爱之心的培养、弘道追求的激励等六个方面,切实加强师范生教育家精神的养成。

“经师”与“人师”统一:我国中小学教师职前培养的关键难点

中小学教师职前培养是其职业生涯的主体中心环节,在此过程中强调“经师”与“人师”的统一,是其可否成为教师职业胜任者的重中之重,也是中小学教师职前培养的关键难点。当前我国中小学教师职前培养偏重“经师”,体现出知识本位、技能本位、实践本位等目标取向。实现“经师”与“人师”的统一培养特别是培养“人师”意义重大,培养“人师”不仅是弘扬中华优秀传统文化的内在要义,而且是落实“立德树人”教育根本任务的必然要求,还是新时代建设高质量教师队伍的根本遵循。目前在实现“经师”与“人师”统一过程中,还面临着培养主体育人理念存在错位、培养对象在专业学习过程中功利化倾向较为严重、培养过程的核心维度和关键内容失之偏颇等问题。基于此,中小学教师职前培养应遵循国家聚焦制度政策建设、学校致力培养过程改革、高校教师夯实“人师”培养能力、师范生主动提升“人师”力等多维协同,最终实现“经师”与“人师”的统一培养。

压裂复杂裂缝中支撑剂输送数值模拟研究

在非常规储层水力压裂施工过程中,水力裂缝容易与天然裂缝交汇形成复杂裂缝,支撑剂的运移和铺置形态直接决定了储层的增产效果。为了研究支撑剂在复杂裂缝中的铺置规律,基于欧拉-欧拉方法建立了支撑剂-压裂液两相流数学模型,并利用复杂裂缝室内实验装置与数值模拟的砂堤铺置形态对比的方式进行了模型验证,结果表明,选取的模型可用于研究滑溜水在复杂裂缝内的携带支撑剂的运移铺置规律。以相似准则为基础,建立了简化的复杂裂缝平板模型,并将砂堤形态参数、砂堤面积进行归一化处理,获得了压裂液排量、黏度、支撑剂粒径、裂缝宽度以及裂缝形态对支撑剂在复杂裂缝中铺置的影响规律。结果表明:增大排量、黏度和减小粒径均有利于支撑剂向裂缝深处运移,并且排量对支缝中的砂堤形态影响最明显,但增大排量不利于支撑剂填充近井地带。缝宽的影响体现在壁面效应,在注入时间相同的情况下,当压裂液黏度从1 mPa·s增加到5 mPa·s时,主缝砂堤的归一化长度平均增加了37.9%,归一化高度平均降低了61.4%。裂缝结构越复杂,所有支缝中的支撑剂铺置面积占比越高,分流作用越大。随着复杂裂缝的支缝数量、级数以及支缝延伸长度的增大,支缝中的砂堤高度与长度均有所降低;相对于T1型裂缝,T3和T5型裂缝中的砂堤长度、高度减小最多。

基于特征相似性和特征规范化的注意力模块

近年来,注意力机制在图像分类、目标检测和语义分割等领域取得了巨大成功,但现有的注意力机制大多只能在通道或空间维度上实现特征融合,这极大限制了其在通道和空间维度上变化的灵活性,导致无法充分利用特征信息。为此,文中提出一种基于特征相似性和特征规范化的、可同时利用特征图各维度信息的卷积神经网络注意力模块FSNAM。该模块由特征相似性模块(FSM)和特征规范化模块(FNM)两部分组成,FSM利用输入特征图的通道特征信息和局部空间特征信息生成一个二维的特征相似性权重图;FNM利用输入特征图的全局空间特征信息生成一个三维的特征规范化权重图;两个模块生成的权重图融合在一起,生成一个三维的注意力权重图,以此实现通道特征信息和空间特征信息的融合。为证明FSNAM的可行性和有效性,进行了消融实验,结果表明:在图像分类任务方面,FSNAM模块对分类网络在CIFAR数据集上的性能提升明显优于其他主流注意力模块;在目标检测任务方面,使用FSNAM模块的目标检测网络对VOC数据集中的小目标和中等大小目标的检测准确率分别提高了3.9和1.2个百分点;在语义分割任务方面,使用FSNAM模块可以提高HRNet模型的性能,在SBD数据集上模型的平均像素准确率提高了0.58个百分点。

师范院校公费师范生乡土情怀研究的现状与展望

公费师范生是乡村教师的重要来源,其乡土情怀直接影响乡村教师队伍建设的质量和水平。乡土情怀是乡村教师对乡村地区、乡村教育、乡村学生发展的关注与关爱,体现为乡村教师对乡村教育的使命感与责任感。本文从公费师范生、乡土情怀、师范院校公费师范生乡土情怀三方面描述了当前的研究现状,并分析了其存在的困境等。从研究可以看出,目前公费师范生乡土情怀较为薄弱,培育过程仍存在困难。如何激发公费师范生内生乡土情怀,如何从国家政策、学校培育、社会参与、家庭教育等多个方面协同发力,提升公费师范生乡土情怀,这是我们亟待解决的现实问题。

面向《教师数字素养》标准的师范生数字素养框架与培养路径

《教师数字素养》行业标准的发布,为师范生数字素养的培养指明了方向。面向教师数字素养框架,开展师范生数字素养框架构建与培养路径设计,能够为推动师范生数字素养理论研究与实践创新提供支持。研究对标教师数字素养框架,参照师范生核心素养相关标准,运用内容分析和对比分析法,构建了包括5个一级维度,13个二级维度,28个三级维度的师范生数字素养框架。在框架构建的基础上,提出了师范生数字素养培养路径:推动师范教育的全面数字化转型,筑牢培养底座;构建以“第一课堂为主,第二课堂为辅”主辅并行的培养体系;组建“校内教师+校际教师”两个共同体支撑的师资队伍;建设“课程资源+实践资源”两个资源库;形成“混合必修+网络选修”两种课程模式;建立师范生数字素养智能测评系统等。

环境监测中干扰采样行为的刑法定性

司法实践中,以物理方式干扰环境监测设备采样的行为常被认定为破坏计算机信息系统罪,最具代表性的是最高人民法院第104号指导性案例。然而,此类判决存在三方面问题,即用司法解释架空刑法条文、用保护法益架空构成要件、用系统目的无法实现代替系统不能正常运行。破坏计算机信息系统罪的保护法益应为计算机信息系统的正常运行,以物理方式干扰采样行为不符合《刑法》第286条第1款和第2款。其中,对第1款中“干扰”的限制应从行为对象和保护法益两方面展开。同时,对司法解释的理解也应遵守罪刑法定原则,与刑法规定一致。

师范大学高质量发展与教育强国建设

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