复分形网络业务的离散小波谱的特征属性及其参数估计

研究发现,高速因特网的合成业务流具有复分形特性.研究统计过程的复分形结构及其特征属性是研究网络业务全尺度下的行为的重要内容.文中基于离散小波变换给出了一种小波谱函数的定义,它可以表征复分形过程的所有阶的统计特性.文中给出了谱函数存在性的证明,并给出了相应的特征属性和条件.最后,基于谱函数的定义,文中给出了小波谱函数的估计方法,并针对实际网络数据进行了小波谱分析.

连接复分形测度的维数及热力学公式

文中在证明三个联合集分形测度维数的基础上，通过一个假设，证明了连接复分形集的维数．同时，利用复分形的热力学形式来处理连接复分形测度．

复分形概念的发展及在天体物理中应用

阐述了分形研究中复分形的概念 。

分形研究中的复分形概念

本文介绍了分形研究领域近几年提出的复分形概念及复分形研究的新进展，对ｆ－ａ谱的计算方法及物理意义也作了较详细的阐述．

分形的若干理论进展

分形(fractal)概念的诞生,深化了人类对大自然的认识,诱发了一些新的科学生长点,揭示和解决了一些难题。目前,分形理论正向自然科学和社会科学各领域渗透。反过来,这些领域又向分形理论提出了许多新课题,使它引进了许多新概念。如多重分形、拉普拉斯分形、子波变换、熵函数和胖分形。这些,构成了当今分形理论的前沿和主流。

天然分形图案:大自然的绮丽之美

从海螺、螺旋星云．再到人类的肺脏结构．我们身边充满各种各样的混沌图案：一种几何形状．被以越来越小的比例反复折叠而产生不能被标准几何所定义的不标准形状和表面的分形图案。分形的数学之美是利用相对简单的等式形成无限复杂的图案：通过多次重复分形生成等式而形成美丽的图案。这些图案是地球上的天然实例．让我们分享它的绮丽之美吧。

两种低能量起搏电极的动态观察

动态观察分形镀复电极 (FCL)和激素释放电极 (SEL)急、慢性期起搏阈值和阻抗的变化规律 ,为临床选择起搏电极和开始低能量起搏的时间提供参考依据。对 33例起搏器患者的 49条电极 ,其中FCL 2 5条、SEL 2 4条 ,用起搏系统分析仪和体外程控仪测定术中及术后 1,3,5 ,7,10 ,15 ,2 2天和 1,2 ,3个月的电压阈值和阻抗 ,计算各次的能量阈值。结果显示术中FCL的起搏阈值低于SEL(P <0 .0 5 )。术后FCL的起搏阈值逐日升高 ,第 10天达峰值 ,然后逐渐降低 ,2 2天时与SEL的起搏阈值相近。术后 2个月 ,FCL起搏阈值又开始低于SEL ,但无显著差异。SEL的起搏阈值始终保持在一个低水平 ,整个随访期无明显波动。两种电极均为低能量起搏电极 :SEL起搏阈值低而稳定 ,FCL的更低但峰值明显 ,两者可分别于术后拆线时和术后

Computer aided stitching approach for dental restoration models

According to the bio-characteristics of the lower and upper cavity surfaces of dental restoration, a stitching approach is proposed based on a virtual zipper working mechanism and a minimization of the surface total curvature energy, which is used to resolve the stitching problems existing during computer-aided design for dental restorations. First, the two boundaries corresponding to the lower and upper surfaces are triangulated based on the zipper working mechanism to generate the initial stitching surface patch, of which the edges are distributed uniformly between the boundaries. Secondly, the initial stitching surface patch is subdivided and deformed to reconstruct an optimized surface patch according to the bio-characteristics of the teeth. The optimized surface patch is minimally distinguishable from the surrounding mesh in smoothness and density, and it can stitch the upper and lower cavity surfaces naturally. The experimental results show that the dental restorations obtained by the proposed method can satisfy both the shape aesthetic and the fitting accuracy, and meet the requirements of clinical oral medicine.

Fractal analysis of fracture surfaces in aluminum borate whisker-reinforced aluminum alloy 6061 composite

The effect of interface reaction on the fractal dimensions of fracture surface in aluminum borate whisker-reinforced aluminum alloy 6061 composite was investigated. The composite was fabricated by squeeze-casting technique. The fracture surfaces created in tensile test were measured by vertical sectioning method. Fractal phenomena were found in two plots, in which the measuring units were from 3 to 15 μm and 1 to 5 μm, respectively. The relation was established between the tensile properties and fractal dimension with measuring units of 3-15 μm. The results show that the ultimate tensile strength increases while the fracture surface roughness increases with fractal dimension increasing due to the change in fracture mode depending on the degree of interface reaction status induced by heat treatment. But when the measuring units are 1-5 μm, fractal dimension does not change with heat treatment.

On the Conjecture of Gackstatter and Laine Concerning Algebraic Differential Equations

In this paper we investigate the form of a class of complex differential equations withadmissible solution and obtain a main result.

Accuracy assessment of ICESat-2 ATL 08 terrain estimates:A case study in Spain

The Ice,Cloud and Land Elevation Satellite-2(ICESat-2),a new spaceborne light detection and ranging(LiDAR)system,was successfully launched on September 15,2018.The ICESat-2 data increase the types of spaceborne LiDAR data archive and provide new control point data for large-scale topographic mapping and geodetic surveying.However,the accuracy of the ATL 08 terrain estimates has not been fully evaluated on a large scale and in complex terrain conditions.This article aims to quantitatively assess the accuracy of ICESat-2 ATL 08 terrain estimates.Firstly,the ICESat-2 ATL 08 terrain estimates were compared with the high-precision airborne LiDAR digital terrain model(DTM),and impacts of acquisition time,vegetation cover type,terrain slope,and season change on the terrain estimation accuracy were analyzed.We get the following conclusions from the analysis:1)the mean and RMSE of the terrain estimates of day acquisitions are 0.22 m and 0.59 m higher than that of night acquisitions;2)the accuracy of the ATL 08 terrain estimates acquired in vegetated areas is lower than those in non-vegetated areas;3)the accuracy of the ATL 08 terrain estimates is inversely proportional to the slope,and the elevation error increases significantly when the terrain slope is larger than 30°;4)in the non-vegetation covered area,the accuracy of the ATL 08 terrain estimates of summer and winter acquisitions has no obvious discrepancy,but in vegetated area,the accuracy of winter acquisitions is significantly better than that of summer acquisitions.This research provides references for the selection and application of ICESat-2 data.

Uncertainty of Slope Length Derived from Digital Elevation Models of the Loess Plateau, China

Although many studies have investigated slope gradient uncertainty derived from Digital Elevation Models(DEMs), the research concerning slope length uncertainty is far from mature. This discrepancy affects the availability and accuracy of soil erosion as well as hydrological modeling. This study investigates the formation and distribution of existing errors and uncertainties in slope length derivation based on 5-m resolution DEMs of the Loess Plateau in the middle of China. The slope length accuracy in three different landform areas is examined to analyse algorithm effects. The experiments indicate that the accuracy of the flat test area is lower than that of the rougher areas. The value from the specific contributing area(SCA) method is greater than the cumulative slope length(CSL), and the differences between these two methods arise from the shape of the upslope area. The variation of mean slope length derived from various DEM resolutions and landforms. The slope length accuracy decreases with increasing grid size and terrain complexity at the six test sites. A regression model is built to express the relationship of mean slope length with DEM resolution less than 85 m and terrain complexity represented by gully density. The results support the understanding of the slope length accuracy, thereby aiding in the effective evaluation of the modeling effect of surface process.

Ab initio Study of Radical-Molecule Reaction： F＋CH2CHCH3

The radical-molecule reaction F＋propene （CH2CHCH3） was studied in detail by using the Becke＇s three parameter Lee-Yang-Parr-B3LYP/6-311G（d,p） and coupled cluster with single, double, and triple excitationsCCSD（T）/6-311＋G（2d,2p）. It is shown that F＋propene reaction mainly occurs through complex-formation mechanism： F attacks the double bond of propene leading to the formation of complex 1 and complex 2. As the two radical complexes are metastable, they can quickly dissociate to H＋C3HsF, CH3＋C2H3F and HF＋C3H5. Based on the ab initio calculations, the CH3＋C2H3F is the main channel, and the H elimination and HF forming channels also provide some contribution to products. The calculated values are in good agreement with the recently reported experimental results.

Traffic sign recognition algorithm based on shape signature and dual-tree complex wavelet transform

A novel traffic sign recognition system is presented in this work. Firstly, the color segmentation and shape classifier based on signature feature of region are used to detect traffic signs in input video sequences. Secondly, traffic sign color-image is preprocessed with gray scaling, and normalized to 64×64 size. Then, image features could be obtained by four levels DT-CWT images. Thirdly, 2DICA and nearest neighbor classifier are united to recognize traffic signs. The whole recognition algorithm is implemented for classification of 50 categories of traffic signs and its recognition accuracy reaches 90%. Comparing image representation DT-CWT with the well-established image representation like template, Gabor, and 2DICA with feature selection techniques such as PCA, LPP, 2DPCA at the same time, the results show that combination method of DT-CWT and 2DICA is useful in traffic signs recognition. Experimental results indicate that the proposed algorithm is robust, effective and accurate.

Complex Wave Solutions for (2+1)-Dimensional Modified Dispersive Water Wave System

The extended Riccati mapping approach^[1] is further improved by generalized Riccati equation, and combine it with variable separation method, abundant new exact complex solutions for the （2＋1）-dimensional modified dispersive water-wave （MDWW） system are obtained. Based on a derived periodic solitary wave solution and a rational solution, we study a type of phenomenon of complex wave.

Classification Method of Graphlike Manifold

In this paper,we give a kind of method which can easily be operated to classify the graphlike manifold with contraction.

A Remark on Contact Hypersurfaces of a Complex Hyperbolic Space

A differentiable manifold is said to be contact if it admits a linear functional f on the tangent bundle satisfying f ∧(df)^(M-1)≠0.This remark obtain the following the classification:Let M be a complete connected contact hyper-surface of CH^2(-4),then M is congruent to one of the following: (i)A tube of radius r>0 around a totally geodesic,totally real hyperbolic space form H^2(-1); (ii)A tube of radius r>0 around a totally geodesic complex hyperbolic space form CH^1(-4); (iii)A geodesic hypersphere of radius r>0,or (iv)A horosphere.

Thermal stress distribution around a thermally-insulated polygonal cutout in graphite/epoxy composite laminates under heat flux

In this study,the effect of influencing parameters on the stress distribution around a polygonal cutout within a laminated composite under uniform heat flux was analytically examined.The analytical method was developed based on the classical laminated plate theory and two-dimensional thermo-elastic method.A mapping function was employed to extend the solution of a perforated symmetric laminate with a circular cutout to the solution of polygonal cutouts.The effect of significant parameters such as the cutout angular position,bluntness and aspect ratio,the heat flux angle and the laminate stacking sequence in symmetric composite laminate containing triangular,square and pentagonal cutouts was studied.The Neumann boundary condition was used at the edges of the thermally insulated polygonal cutout.The laminate was made of graphite/epoxy(AS/3501) material with two different stacking sequences of [30/45]sand[30/0/-30]_(s).The analytical solutions were well validated against finite element results.