The Growth Theorem for Strongly Starlike Mappings of Order α on Bounded Starlike Circular Domains

The authors obtain the growth and covering theorems for strongly starlike mappings of order α on bounded starlike circular domains.This kind of domain discussed is rather general,since the domain must be starlike if exists a normalized biholomorphic starlike mapping on it.

Application of pseudo-random frequency domain electromagnetic method in mining areas with strong interferences

Due to the strong electromagnetic interferences and human interference,traditional electromagnetic methods cannot obtain high quality resistivity data of mineral deposits in Chinese mines.The wide field electromagnetic method(WFEM),in which the pseudo-random signal is taken as the transmitter source,can extract high quality resistivity data in areas with sever interference by only measuring the electric field component.We use the WFEM to extract the resistivity information of the Dongguashan mine in southeast China.Compared with the audio magnetotelluric(AMT)method,and the controlled source audio-frequency magnetotelluric(CSAMT) method,the WFEM can obtain data with higher quality and simpler operations.The inversion results indicate that the WFEM can accurately identify the location of the main ore-body,which can be used for deep mine exploration in areas with strong interference.

Evaluation of strongly singular domain integrals for internal stresses in functionally graded materials analyses using RIBEM

An accurate evaluation of strongly singular domain integral appearing in the stress representation formula is a crucial problem in the stress analysis of functionally graded materials using boundary element method.To solve this problem,a singularity separation technique is presented in the paper to split the singular integral into regular and singular parts by subtracting and adding a singular term.The singular domain integral is transformed into a boundary integral using the radial integration method.Analytical expressions of the radial integrals are obtained for two commonly used shear moduli varying with spatial coordinates.The regular domain integral,after expressing the displacements in terms of the radial basis functions,is also transformed to the boundary using the radial integration method.Finally,a boundary element method without internal cells is established for computing the stresses at internal nodes of the functionally graded materials with varying shear modulus.

关于代数L-domain的一个刻画定理

引入了强core紧拓扑空间的概念,给出了代数L-domain的刻画定理,其主要结果是:偏序集D是代数L-domain当且仅当对每个强core紧拓扑空间X,函数空间[X→D]是代数L-domain.

A STRONG SOLUTION OF NAVIER-STOKES EQUATIONS WITH A ROTATION EFFECT FOR ISENTROPIC COMPRESSIBLE FLUIDS

We study the initial boundary value problem for the three-dimensional isentropic compressible Navier-Stokes equations in the exterior domain outside a rotating obstacle,with initial density having a compact support.By the coordinate system attached to the obstacle and an appropriate transformation of unknown functions,we obtain the three-dimensional isentropic compressible Navier-Stokes equations with a rotation effect in a fixed exterior domain.We first construct a sequence of unique local strong solutions for the related approximation problems restricted in a sequence of bounded domains,and derive some uniform bounds of higher order norms,which are independent of the size of the bounded domains.Then we prove the local existence of unique strong solution of the problem in the exterior domain,provided that the initial data satisfy a natural compatibility condition.

ROPER-SUFFRIDGE EXTENSION OPERATOR ON A REINHARDT DOMAIN

Let pj ∈ N and pj≥ 1, j = 2, …, k, k ≥ 2 be a fixed positive integer. We introduce a Roper-Suffridge extension operator on the following Reinhardt domain ΩN ={z =（z1, z′2,…, z′k）′∈ C × C^n2×…× Cnk： ｜z1｜^2＋ ｜｜z2｜｜2^p2＋ … ＋ ｜｜zk ｜｜k^pk〈 1} given〈1} give by F（z）=（f（z1）＋f＇（z1）∑j=2 kPj（zj,（f＇（z1））1/p2 z2＇,…,（f＇（z1））1/pkzk＇）＇, where f is a normaljized biholomorphic function k（z） =（f（z1） ＋ f′（z1）=2 on the unit disc D, and for 2 ≤ j ≤ k, Pj ： C^nj→ C is a homogeneous polynomial of degree pj and zj =（zj1, …, zjnj）′∈ C^nj, nj ≥ 1, pj ≥ 1,｜｜zj｜｜j =（∑l=1 nj｜zjl｜^pj）1/pj. In this paper, some conditions for Pjare found under which the loperator p ｜zjl｜pj=1reserves the properties of almost starlikeness of order α, starlikeness of order αand strongly starlikeness of order α on ΩN, respectively.

Non-stationary Buffeting Response Analysis of Long Span Suspension Bridge Under Strong Wind Loading

The non-stationary buffeting response of long span suspension bridge in time domain under strong wind loading is computed. Modeling method for generating non-stationary fluctuating winds with probabilistic model for non-stationary strong wind fields is first presented. Non-stationary wind forces induced by strong winds on bridge deck and tower are then given a brief introduction. Finally,Non-stationary buffeting response of Pulite Bridge in China,a long span suspension bridge,is computed by using ANSYS software under four working conditions with different combination of time-varying mean wind and time-varying variance. The case study further confirms that it is necessity of considering non-stationary buffeting response for long span suspension bridge under strong wind loading,rather than only stationary buffeting response.

冀东金厂峪金矿剪切带控矿规律及找矿建议

冀东金厂峪金矿为典型受构造作用控制的矿床,金矿体主要产于NNE向脆-韧性片理化带内的强变形带之中,直接控矿构造为叠加于强变形带之上的NNE向燕山期脆性断裂构造。本文在详细的野外调查基础上进行了构造分期配套,建立了弱变形域控岩+强变形带赋矿的透镜体控矿模式,结合矿体赋存和矿化富集规律总结,提出了韧脆性片理化带深部、两侧次级平行构造等找矿方向。

电磁防护技术发展综述与展望

针对复杂电磁对抗环境中电子信息装备面临的强电磁环境威胁以及防护加固需求,对强电磁防护技术的发展现状进行了综述,并提出了强电磁系统级综合防护的发展展望。强电磁防护是为了保证电子信息装备在强电磁环境中免受损伤或损毁的技术手段,从电磁波的耦合途径分析了当前电磁防护的重点和难点,然后分别以限幅器技术、频率滤波技术、能量选择防护技术三个方面对前门防护技术的发展现状进行了分析总结,最后从新型屏蔽材料和防护器件两个方面对新型电磁防护技术进行了展望,并从前后门一体防护、场路一体防护、多域联合防护三个角度对系统级电磁防护进行了总结,为电子信息装备在复杂电磁环境下的电磁防护加固设计提供了支撑。

基于知识图谱的浓香型白酒酿造微生物可视化分析

为了深入了解浓香型白酒酿造微生物领域的研究成果与研究进展,该研究基于中国知网数据库及Web of Science核心数据库,对该领域在2009—2022年中英文文献进行查阅与筛选。分别从年度发文量、关键词、作者及科研机构等方面,采用文献计量学的方法,对该领域1017篇中文文献及130篇英文文献进行知识图谱可视化分析。结果表明,浓香型酿造白酒微生物领域处于蓬勃发展阶段,随着时间的推移,发文数量及质量都在不断提升。研究热点集中于窖泥、微生物多样性、大曲、己酸菌、酒醅、风味物质、己酸乙酯。同时,该领域科研人员沟通密切,高校及科研机构与浓香型白酒企业间合作紧密。通过该文综合分析,为科研人员了解该领域研究方向及热点,开展学术合作及交流提供了参考。

中红外大气强吸收波段地气杂波全球空间分布研究

中红外大气强吸收波段(2.7和4.3μm附近)具有抑制背景杂波信号的特点,常被用于红外探测卫星载荷上,实现目标的稳定探测与跟踪。背景杂波起伏水平对红外目标探测具有重要影响,研究中红外2.7和4.3μm波段附近的地气杂波空域起伏具有重要意义。首先,利用MODTRAN辐射传输模型迭代求解6种标准大气模式下水汽和CO_(2)的光学厚度(OD),根据OD>1的准则筛选强吸收波段,并对各种大气模式下的波段计算结果取交集,最终确定的强吸收波段为:2.52~2.83和4.18~4.47μm。然后,根据遥感卫星数据产品、数据同化资料生产出背景地表和大气的全球月均产品。其中,结合MODIS短波红外和中红外4个波段(2.13、3.75、3.96和4.05μm)的月均地表反射率/发射率产品(MYD09A1/MOD11C3),采用非负矩阵分解(NMF)的方法重建出强吸收波段处的全球地表反射率产品;根据ERA5再分析数据生产全球地表温度月均产品;水汽和云光学厚度(COT)全球月均产品分别由MODIS大气产品(MOD05_L2和MOD06_L2)拼接融合得到;CO_(2)全球月均产品来自OCO-2卫星的数据同化产品;为了各类数据产品的空间匹配和节约计算资源,将全球产品限制在南北纬60°区间范围内并重采样至1°×1°的空间分辨率;接着,在有云和无云情况下,分别逐像元仿真计算两个强吸收波段的背景杂波强度,分析杂波的空间分布规律。最后,利用11×11方窗邻域统计法,对仿真结果进行杂波空域起伏的计算,换算95%概率下的杂波起伏,并进行直方图统计,从杂波抑制的角度,给出两个吸收波段的红外目标探测性能对比。研究结果表明:有云情形下,2.52~2.83μm波段背景杂波起伏水平具有“点状峰值、区域增强、整体低值”的特征;4.18~4.47μm波段杂波起伏水平呈现“区域高值、片状增强、高纬低值”的特征。无云情形下,2.52~2.83μm波段背景杂波起伏水平在水汽含量低值区,有较大增幅;4.18~4.47μm波段杂波起伏水平总体较低,大部分控制在2×10^(-4)W/m^(2)/sr/μm以内。在全球尺度上,有云时,2.52~2.83μm波段的红外目标探测性能较优,无云时,4.18~4.47μm波段的红外目标探测性能较优;研究结果能够为探测红外目标提供空域规律和谱段优选的参考依据,对增强目标的可探测性具有重要价值。

小波域强面波衰减方法研究

基于离散小波变换(DWT)阈值法压制面波适用于面波、反射波频带重叠的少数尺度范围去噪的特点,文中利用理论模型分析比较了四种阈值选取准则对DWT阈值方法压制面波结果的影响,并选出最佳准则。在此基础上首先使用改进的DWT阈值方法初步压制面波,然后再利用联合二维物理小波标架去噪(PWFD)方法压制剩余面波能量。理论记录和实际资料处理结果表明:DWT阈值去噪联合PWFD阈值去噪既可以较好地压制面波,又可以较好地实现有效信号的保真。该方法去噪效果优于F-K方法及其他方法。

强噪声条件下激光光斑图像预处理方法研究

为了研究强噪声光斑图像的抑噪方法,采用基于小波阈值法和形态学滤波的级联算法及小波域中值滤波法进行预处理,以信噪比、均方根误差和光强分布作为评估标准,并将处理效果与其他方法对比。结果表明:小波域中值滤波处理效果优于空域中值滤波;级联法的抑噪和光斑特征恢复效果更优于传统方法,其中对-2.0843dB的原低信噪比图像处理后的信噪比、均方根误差分别约为小波变换和空域中值滤波法的1.34、0.81倍和3.14、0.50倍;且原图像信噪比越低,其处理效果相对于传统方法的优越性越明显。

ON THE GENERALIZATIONS OF DENJOY-WOLFF THEOREM

We consider generalizations of Denjoy-Wolff theorem on strongly pseudoconvex domains. Beardon [3] gave a general Denjoy-Wolff theorem in hyperbolic domain in the complex plane. Our main results are generalizations of Beardon＇s result in a higher dimensional setting.

基于Adaboost的视频文本定位

提出了一种基于Adaboost的视频文本定位的新方法。首先我们提取视频图像中的连通域,经过对视频文本区域分析,提取了视频文本的5类特征,然后利用这5类特征经过分类与回归决策树构造了Adaboost强分类器,最后将候选文本区域送入强分类器,得到正确的文本区域。实验结果表明本方法不仅对视频帧图像中字体、大小和颜色多变的文本具有很好的定位效果而且还实现了视频文本定位要求的快速性和准确性的特点。

PTW整环的刻画

引入了PTW整环的概念,刻画了PTW整环的局部化性质,然后对PTW整环的拉回图进行了研究,证明了若RDTF是强M ilnor方图,则w-d im(R)=m ax{htTM+w-d im(D),w-d im(T)},最后通过例子说明了PTW整环不是TW整环.

小波方法及其力学应用研究进展

小波理论在进行信号处理与函数逼近时体现出非常独特的时频局部性与多分辨分析能力,小波基函数则可兼具正交性、紧支性、低通滤波与插值性等优良的数学性质,这均使得小波分析理论在计算数学与计算力学领域具有很大的应用潜力,也进一步为这些领域的突破性发展带来了新的契机.自20世纪90年代以来,大量的研究已经证明,基于小波理论的数值方法在微分方程求解中具有非常明显的优势,但与此同时也暴露出了一些由小波基函数本身与其特有逼近方式所造成的数值计算应用局限.为了促进小波理论在计算数学与力学领域的创新性应用,给研究人员提供新的研究视角,该文简要梳理了小波分析的发展背景以及基于小波理论的数值方法的研究历史,并着重讨论分析了后者所面临的问题,以及近年来针对这些问题中的基础性难题所取得的研究进展.这些总结与评述有望为后续进一步发展并完善基于小波理论的定量数学求解方法,以及拓展其在力学乃至广泛工程问题求解中的应用提供有意义的参考.

几乎Prüfer整环多项式环的维数和分式环

证明了如下2个结果:若R是几乎Prfer整环,则dimR[X1,…,Xn]=dimR+n;若R〈X〉■Rc〈X〉是根扩张,则R是几乎Prfer整环当且仅当R〈X〉是几乎Prfer整环.

用改进的变形参数法求解强参数激励Mathieu方程

为了研究大幅值参数激励M ath ieu方程,通过引入新的变换,将强参数激励系统转化为弱参数激励系统,利用改进的变形参数法求解无阻尼项的M ath ieu方程,分别得到具有π和2π方程的周期解和相应的过渡曲线,并利用过渡曲线得到方程的不稳定区域和稳定域.结果表明,该方法与文献[7]得到的过渡曲线基本吻合,通过数值法验证了用该方法得到稳定域比文献[7]的结果更为合理.

基于强系数关系的水印算法

数字水印技术是保护数字媒体安全的一种有效手段,从健壮性角度考虑,采用变频域方法实现数字水印比较理想。通过对原始图像进行8×8分块、置乱变换、调整交流系数满足较强关系,提出了一种基于强系数关系的DCT域盲图像水印算法,实验结果表明,该算法对几种常见图像处理攻击有很强的健壮性,由于密钥的使用,算法本身也具有一定的安全性。