Spatial Autocorrelation and Localization of Urban Development

A nonlinear analysis of urban evolution is made by using of spatial autocorrelation theory. A first-order nonlinear autoregression model based on Clark’s negative exponential model is proposed to show urban population density. The new method and model are applied to Hangzhou City, China, as an example. The average distance of population activities, the auto-correlation coefficient of urban population density, and the auto-regressive function values all show trends of gradual increase from 1964 to 2000, but there always is a sharp first-order cutoff in the partial auto- correlations. These results indicate that urban development is a process of localization. The discovery of urban locality is significant to improve the cellular-automata-based urban simulation of modeling spatial complexity.

A new beam element for analyzing geometrical and physical nonlinearity

Based on Timoshenko＇s beam theory and Vlasov＇s thin-walled member theory, a new model of spatial thin-walled beam element is developed for analyzing geometrical and physical nonlinearity, which incorporates an interior node and independent interpolations of bending angles and warp and takes diversified factors into consideration, such as traverse shear deformation, torsional shear deformation and their coupling, coupling of flexure and torsion, and the second shear stress. The geometrical nonlinear strain is formulated in updated Lagarange （UL） and the corresponding stiffness matrix is derived. The perfectly plastic model is used to account for physical nonlinearity, and the yield rule of von Mises and incremental relationship of Prandtle-Reuss are adopted. Elastoplastic stiffness matrix is obtained by numerical integration based on the finite segment method, and a finite element program is compiled. Numerical examples manifest that the proposed model is accurate and feasible in the analysis of thin-walled structures.

Influence of nonlinear spatial distribution of stress and strain on solving problems of solid mechanics

The stress and the strain should be defined as statistical variables averaged over the representative volume elements for any real continuum system.It is shown that their nonlinear spatial distributions undermine the classical framework of solid mechanics and may cause non-ignorable errors to the solutions.With considering the high-order gradients of the stress and the strain,a two-step solution scheme is proposed to compensate for the influence.Through a revisit to three simple but typical problems,i.e.,the hole size-dependence of the fracture strength of perforated plates,the indentation depth-dependence of the measured elastic modulus by micro-indentation tests,and the tensile necking of metallic materials as well as hyperelastic materials,the effect of the nonlinear spatial distribution of stress and strain on solving these problems is illustrated.The observed size effect and the instability of deformation can be quantitatively explained if the effect is properly considered by the proposed method.

Non-collinear nonlinear properties of steel and LY12 aluminum alloy

The sensitivity of collinear nonlinear nondestructive testing technique based on harmonic detection is high,but the results are vulnerable to interference from other nonlinear of experiment sources,which leads to this technology limited in industrial applications.To solve this problem,a non-collinear nonlinear ultrasonic testing experimental system is established based on non-collinear beam mixing technology.The non-collinear nonlinear response is observed in the steel and LY12 aluminum alloy.The results show that:1 Based on the benefits of space selection,mode conversion,frequency and steerable optional of non-collinear beam mixing technology,the interference of system nonlinear effects can be suppressed effectively;2 Mode conversion and beam mixing are present in steel and LY12 aluminum alloy,and the non-collinear non-linear response of LY12 aluminum alloy is stronger than steel and the measurement results are more obvious;3 The technology has the feasibility to evaluate the uniformity of material internal.

GACNet: A Generative Adversarial Capsule Network for Regional Epitaxial Traffic Flow Prediction

With continuous urbanization,cities are undergoing a sharp expansion within the regional space.Due to the high cost,the prediction of regional traffic flow is more difficult to extend to entire urban areas.To address this challenging problem,we present a new deep learning architecture for regional epitaxial traffic flow prediction called GACNet,which predicts traffic flow of surrounding areas based on inflow and outflow information in central area.The method is data-driven,and the spatial relationship of traffic flow is characterized by dynamically transforming traffic information into images through a two-dimensional matrix.We introduce adversarial training to improve performance of prediction and enhance the robustness.The generator mainly consists of two parts:abstract traffic feature extraction in the central region and traffic prediction in the extended region.In particular,the feature extraction part captures nonlinear spatial dependence using gated convolution,and replaces the maximum pooling operation with dynamic routing,finally aggregates multidimensional information in capsule form.The effectiveness of the method is evaluated using traffic flow datasets for two real traffic networks:Beijing and New York.Experiments on highly challenging datasets show that our method performs well for this task.

Disaster Risk Reduction and Management: Recalling the Need for Paradigm Shift in Definition

The paper articulates the need for a paradigm shift in defining the basis of what constitutes a disaster. This new framework must be sensitive to the need for a more theoretical approach to inform disaster and hazard management. Central to this is that the resulting approach cannot be muddled in linear rational and procedural doctrines but appreciate the dynamics of complex nonlinearity of disaster events. By engaging in thought experiment and critical analysis of existing literature, the paper deconstructs the normative paradigm of defining disaster. The end is to inform disaster management and risk reduction intervention and mitigation programmes. The presented alternative approach is sensitive of the need to equally include;spatial, political, social, parameters. These are appreciated as being equally important as those dealing with ecological and economic. The resulting not only include other elements, but also expands the definition to the complex conditions inherent in the origin of phenomena to the interaction of the phenomena with multiple and complex socio-spatial and demographic dynamics, and then appreciating the complex results of this nonlinear interaction. The need for a more substantive definition of disaster underlines the pre-analysis that is necessary for implementation of mitigation and prevention strategies. That disasters are becoming more complex is synonymous with the complexities inherent in post-war development dynamics.

Image encryption using spatial nonlinear optics

Optical technologies have been widely used in information security owing to its parallel and high-speed processing capability.However,the most critical problem with current optical encryption techniques is that the cyphertext is linearly related with the plaintext,leading to the possibility that one can crack the system by solving a set of linear equations with only two cyphertext from the same encryption machine.Many efforts have been taken in the last decade to resolve the linearity issue,but none of these offers a true nonlinear solution.Inspired by the recent advance in spatial nonlinear optics,here we demonstrate a true nonlinear optical encryption technique.We show that,owing to the self-phase modulation effect of the photorefractive crystal,the proposed nonlinear optical image encryption technique is robust against the known plaintext attack based on phase retrieval.This opens up a new avenue for optical encryption in the spatial nonlinear domain.

Vortex and Gaussian Solitons of (3+1)-Dimensional Spatially Modulated Cubic-Quintic-Septimal Nonlinear Schrdinger Equation with External Potential

Based on the variable separation principle and the similarity transformation, vortex soliton solution of a （3＋1）-dimensional cubie-quintic-septimal nonlinear Schrodinger equation with spatially modulated nonlinearity under the external potential are obtained in the spatially modulated cubic-quintic-septimal nonlinear media. If the topological charge m = 0 and m ≠0, Gaussian solitons and vortex solitons can be constructed respectively. The shapes of vortex soliton possess similar structures when the value of l - m is same. Moreover, all phases of vortex solitons exist m-jump with the change of every jump as 2π/m-jumps, and thus totally realize the azimuthal change of 21r around their cores.