A Modeling Framework for Jamming Structures

Jamming is a structural phenomenon that provides tunable mechanical behavior. A jamming structure typically consists of a collection of elements with low effective stiffness and damping. When a pressure gradient, such as vacuum, is applied, kinematic and frictional coupling increase, resulting in dramatically altered mechanical properties. Engineers have used jamming to build devices from tunable-stiffness grippers to tunable-damping landing gear. This study presents a rigorous framework that systematically guides the design of jamming structures for target applications. The force-deflection behavior of major types of jamming structures (i.e., grain, fiber, and layer) in fundamental loading conditions (e.g., tension, shear, and bending) is compared. High-performing pairs (e.g., grains in compression, layers in shear, and bending) are identified. Parameters that go into designing, fabricating, and actuating a jamming structure (e.g., scale, material, geometry, and actuator) are described, along with their effects on functional metrics. Two key methods to expand on the design space of jamming structures are introduced: using structural design to achieve effective tunable-impedance behavior in specific loading directions, and creating hybrid jamming structures to utilize the advantages of different types of jamming. Collectively, this study elaborates and extends the jamming design space, providing a conceptual modeling framework for jamming-based structures.     

压电智能结构的一种建模方法

阐述了压电智能结构建模的几种方法,给出了阻抗法建模的基本概念。并以简支薄板为例,将阻抗法与静力法及实验法比较,结果表明,阻抗法能抓住致动器与结构之间动态耦合的物理实质,是一种方便、直观、精确的建模方法。     

Effect of Number of Coupled Structures on the Segmentation of Brain Structures

This paper reports the effect of the coupling information on the performance of model-based segmentation of the brain structures from magnetic resonance images (MRI). We have developed a three-dimensional, nonparametric, entropy-based, and multi-shape method that benefits from coupling of the shapes. The proposed method uses principal component analysis (PCA) to develop shape models that capture structural variability and integrates geometrical relationship among different structures into the algorithm by coupling them (limiting their independent deformations). At the same time, to allow variations of the coupled structures, it registers each structure individually when building the shape models. It defines an entropy-based energy function which is minimized using quasi-Newton algorithm. Probability density functions (pdf) are estimated iteratively using nonparametric Parzen window method. In the optimization algorithm, analytical derivatives are used for maximum speed and accuracy. Sample results are given for the segmentation of caudate, thalamus, putamen, pallidum, hippocampus, and amygdala illustrating superior performance of the proposed method compared to the most similar method in the literature. The similarity of the results obtained by the proposed method with the expert segmentation is 4% to 12% higher than that of the most similar method. Experimental studies show that the proposed coupling method, which regulates shape variability during segmentation, improves accuracy of the results of the proposed method by 6% and those of the other method by 1%. In addition, the more the structures are used in the coupling process, the more accurate the results are obtained.     

Electromagnetic Pulse Interaction with Mammalian Cranial Structures

The transmitted field strengths in homogeneous spherical models of human and animal heads are determined as a function of time and position, using frequency analytic techniques for an impinging pulse of Gaussian character. A relaxation process and constant conductivity are assumed for the electrical behavior of brain matter. The constant conductivity process predicts continued decrease in pulse amplitude as it advances in the head starting from the leading surface; however, the relaxation process predicts reduction only from the surface to the center. Moreover, it appears that the transmitted pulse in a spherical model of the head is always related to the time derivative of the incident radiation. Numerical results indicate that the transmitted pulse amplitude is quite small and can be estimated using the constant conductivity model.     

Novel Methods for Modeling of Multiple Vias in Multilayered Parallel-Plate Structures

This paper presents novel modeling methods for accurate and efficient analysis of coupling of multiple vias in finite-sized multilayered parallel-plate structures. The new modeling methods address two open problems related to the modal expansion with the T-matrix method for the analysis of via coupling. First, a novel boundary modeling method, called the frequency-dependent cylinder layer (FDCL), is proposed to resolve the open problem of boundary modeling. In the FDCL, virtual cylinders with dynamic radii are postulated to approximate the original finite-sized boundary of parallel-plate structures. Second, a generalized T-matrix model, which is derived by the mode-matching technique, is created to characterize the coupling effect for vias penetrating more than one layer in a multilayered structure. With the two open problems successfully solved, the modal expansion with the T-matrix method incorporating the FDCL boundary modeling method and the generalized T-matrix model can now be fully utilized for efficient and accurate analysis of finite-sized multilayered parallel-plate structures with a large number of vias. Both numerical and experimental verifications are presented to validate the new modeling methods.      

Mathematical Modeling of Promising Structures of Metal Oxides

Russian Microelectronics - Information about the structure and properties of materials is especially important when working with micro-and nanoscale objects due to the complexity of obtaining it....     

Neighboring Coefficients Preservation for Signal Denoising

For traditional thresholding denoising, the wavelet coefficients are thresholded without considering the information of other coefficients. In this paper, we propose a novel denoising approach which incorporates the neighboring coefficients into signal denoising. Our approach not only preserves the coefficients above the threshold, but it also preserves the coefficients predominated by useful components although their magnitudes are smaller than or equal to the threshold. Experimental results illustrate that the proposed approach is better than the NeighShrink scheme and the hard thresholding in both of the visual perception and the numerical results.     

用于平面多层介质结构的全波算法

提出一种平面多层介质带线结构的新型全波算法.该方法基于电场积分方程,由伽略金法求解相应的矩阵方程,从而容易获得表征电路特性的网络参数(如散射参数、导纳).以低温共烧陶瓷(LTCC)带通滤波器为数值算例,并采用Momentum仿真对比,结果表明该方法准确、速度快,可以大大提高格林函数的计算效率.     

基于高阶叠层型基函数的微波管慢波结构的三维有限元模拟

采用基于二阶叠层基函数的矢量有限元法对微波管慢波电路进行了三维数值模拟,从而准确求出其高频参数.为了提高慢波电路有限元仿真效率,提出了一种方便快速去除慢波电路有限元仿真中伪直流模式的方法,同时利用一种p-型乘法的多重网格预处理隐式重启Arnoldi法快速求解最后的大型广义本征矩阵.在此基础上开发了一个微波管高频电路模拟器的子模块一多重网格本征求解器.通过仿真实际的慢波电路,模拟器的计算精度得到验证,同时显示了其优越的计算性能.     

一种改进的自适应背景建模视频分割方法

针对传统的自适应背景建模难以解决背景复杂以及外界光照变化等因素影响视频分割质量的问题,提出了一种改进的自适应背景建模视频分割方法。该方法首先对彩色图像建立高斯背景模型,然后对背景模型进行更新,最后通过对高斯分布准则进行改进使前景目标分割性能得到提高。仿真实验表明,该方法能够准确建立背景模型,准确分割前景目标,较传统算法具有更强的鲁棒性。     

Modeling of Gate Current and Capacitance in Nanoscale-MOS Structures

By applying a fully self-consistent solution of the Schrodinger-Poisson equations, a simple unified approach has been developed in order to study the gate current and gate capacitance of nanoscale-MOS structures with ultrathin dielectric layer. In this paper, the model has been employed to investigate various gate structure and material combinations, thereby demonstrating wide applicability of the present model in the design of nanoscale-MOSFET devices. The results obtained by applying the proposed model are in good agreement with experimental data and previous models in the literature. A new result concerning optimum nitrogen content in HfSiON high-k gate-dielectric structure reported in this paper requires experimental verification through device fabrication     

Unsupervised Video Object Segmentation via Weak User Interaction and Temporal Modulation

In unsupervised video object segmentation(UVOS), the whole video might segment the wrong target due to the lack of initial prior information. Also, in semi-supervised video object segmentation(SVOS), the initial video frame with a fine-grained pixel-level mask is essential to good segmentation accuracy. It is expensive and laborious to provide the accurate pixel-level masks for each training sequence. To address this issue, We present a weak user interactive UVOS approach guided by a simple huma...     

基于体分割重建的增强现实交互系统

利用手持彩色和深度摄像头(Kinect)作为图像采集设备,在KinectFusion算法的基础上进行了扩展,实现了一个人与虚拟屏幕直接触碰交互的增强现实系统。本文提出一种腐蚀膨胀的方法提取场景中的运动物体,借助深度图采用分层渲染的方法实现虚实物体互遮挡效果,最后采用一种体素碰撞检测的方法解决人与屏幕的碰撞检测问题。系统的实现过程中采取GPU并行处理,显著提高了算法速度。     

Wave-Field Interaction With Complex Structures Using Equivalence Principle Algorithm

A domain decomposition scheme based on the equivalence principle, similar to Huygens' principle, for integral equation solvers and the method of moments is introduced. The equivalence principle allows the replacement of unknown currents distributed in a volume in space by equivalence currents residing on the surface that bounds the volume. It also allows the dissociation of the solution of one region from that of another region. In this manner, problems of high complexity can be encapsulated by surfaces of simpler shapes using less unknowns. It can aid in parallel algorithms, reusability of solutions, as well as improving the condition number of a matrix system when disparate mesh or adaptive mesh are needed. The challenge arises when an equivalence surface intercepts a current-carrying conductor, because the breakup of the current into separate pieces gives rise to charge singularity. A junction basis can be used to mitigate this singularity. However, a better solution is to introduce a tap basis to model the current that intercepts with the equivalence surfaces. Using this scheme, the current continuity is conserved and the singularity of the charges is avoided. The solution is shown to be accurate     

Interaction of Two Cross-Polarized Electromagnetic Waves with Mammalian Cranial Structures

A study has been made of the interaction of two crosspolarized plane electromagnetic waves with six-layered spherical models of a mammalian head. The numerical results indicate that the absorbed powers induced inside small animal and human heads by incident circularly polarized waves and linearly polarized waves are very similar except that the absorbed power in the planes transverse to the direction of propagation is uniform for the cross-polarized wave. It is also shown that the average absorbed power depends strongly on the frequency and head size involved. The maximum absorbed powers in a given size spherical head vary only slightly with frequency for the two frequencies studied. However, since a greater amount of the absorbed power occurs in the inner sphere representing the brain of a human head when 918 MHz rather than 2450 MHz is used, the former constitutes a greater health hazard to man at the same incident power.     

图像分割技术在多媒体人机交互领域的应用研究

随着多媒体技术的发展,计算机人机交互界面正向多媒体人机交互界面阶段过渡;在多媒体信息处理中引入图像分割技术,将使每个媒体对象都能脱离它的原有环境而独立表现,用户可以选择性地与某一个或几个对象交互,从而使人机交互能力大幅度提高.文中在分析用于图像分割的各种边界技术、区域技术及其应用特点的基础上,研究了图像分割技术在多媒体人机交互领域的应用前景和存在的主要问题,并且提出了在图像分割过程中引入图像匹配技术的可能性.     

Linear Analysis of Traveling Wave Tubes with Nonuniform Lossy Interaction Structures

A linear theory model is developed to analyze traveling wave tubes (TWT) employing distributed wall loss. The loss can be a function of position. The electronic and circuit equation are derived, taking into account the spatial variation of the circuit loss. This model can be used to provide a first-cut design of the TWT.