A macro model of spin-transfer torque magnetic tunnel junction

The precise compact modeling of magnetic devices is pivotal for the integrated design of spin-transfer torque magnetic tunnel junction(STT-MTJ)in conjunction with CMOS circuitry.This work presents a macro model for an STT-MTJ which is compatible with SPICE simulation platforms.The model accurately replicates the electrical performance of the MTJ,encompassing the resistance-voltage characteristics and the pulse-width-dependent state switching behavior,and is validated with various experimental data.Additionally,the impact of process variations,particularly those affecting the MTJ diameter and barrier thickness is investigated and summarized in a corner model.Monte Carlo simulations demonstrate that our adaptable and streamlined model can be efficiently incorporated into the design of integrated circuits.

Macro modeling and analysis of traffic flow with road width

The macro modeling and the solution of traffic flow with road width were investigated.Firstly,a new macro model with the consideration of road width was proposed.Secondly,the effects of road width on uniform flow and small perturbation were studied.The analytical and numerical results show that widening (shrinking) road can enhance (reduce) the equilibrium speed and flow,and the increments (decrements) will increase with the absolute value of road width gradient.In addition,the numerical results illustrate that the new model can describe the effects of road width on the evolutions of uniform flow and small perturbation.

Macro Model Study for Nonlinear Spring of Tense Torsion Bar in Gap-Closing Type Electrostatic Micromirror

Nonlinear spring characteristics of the tense torsion bar in the gap-closing type electrostatic micromirror are examined. The macro model is introduced for the experimental study. The tension applied in the torsion bar is well controlled using the electromagnetic attraction. This controllability is suited for clearing the nonlinear nature. The tension is confirmed to have the effect to widen the controllable angle range of the mirror suppressing the pull-in. The pull-in angle is observed to increases to about 74% of the mechanical limit angle at the tension of 0,96 N. This is significantly larger than 44% of the case with the linear spring. The larger resonant frequency is maintained. The hardening of the spring can keep the balance with the electrostatic force over the limit of the linear spring. The observed features are explained reasonably with the combination of twisting and bending displacements of the torsion bar.

A Fractional Micro-Macro Model for Crowds of Pedestrians Based on Fractional Mean Field Games

Modeling a crowd of pedestrians has been considered in this paper from different aspects. Based on fractional microscopic model that may be much more close to reality, a fractional macroscopic model has been proposed using conservation law of mass. Then in order to characterize the competitive and cooperative interactions among pedestrians, fractional mean field games are utilized in the modeling problem when the number of pedestrians goes to infinity and fractional dynamic model composed of fractional backward and fractional forward equations are constructed in macro scale. Fractional micromacro model for crowds of pedestrians are obtained in the end. Simulation results are also included to illustrate the proposed fractional microscopic model and fractional macroscopic model, respectively. © 2014 Chinese Association of Automation.

Behavior of reinforced concrete structural walls with various opening locations: experiments and macro model

Two experimental tests of three-storied reinforced concrete structural walls having large openings were performed.Based on an original macro model,a multiple modified macro-model was proposed to develop a simple method to design a reinforced concrete structural wall with large openings and various opening locations.The interaction between reinforcement ties and concrete struts formed along the perimeter of openings was neglected in the original model.However,the strut-and-tie node was proposed to take account of such interaction in the proposed model.The predicted behavior of two specimens using such a proposed model was compared with the experimental results.It is shown that the behavior of structural walls with large openings could be modeled well using the proposed model.Moreover,the study indicates that the proposed model is applicable even in cases of multi-story structural walls having large openings and various opening locations.

Image processing algorithm acceleration using reconfigurable macro processor model

The concept and advantage of reconfigurable technology is introduced. A kind of processor architecture of re configurable macro processor (RMP) model based on FPGA array and DSP is put forward and has been implemented. Two image algorithms are developed: template-based automatic target recognition and zone labeling. One is estimating for motion direction in the infrared image background, another is line picking-up algorithm based on image zone labeling and phase grouping technique. It is a kind of 'hardware' function that can be called by the DSP in high-level algorithm. It is also a kind of hardware algorithm of the DSP. The results of experiments show the reconfigurable computing technology based on RMP is an ideal accelerating means to deal with the high-speed image processing tasks. High real time performance is obtained in our two applications on RMP.

Micro-macro models for viscoelastic fluids:modelling,mathematics and numerics

This paper is an introduction to the modelling of viscoelastic fluids,with an emphasis on micromacro(or multiscale) models.Some elements of mathematical and numerical analysis are provided.These notes closely follow the lectures delivered by the second author at the Chinese Academy of Science during the Workshop "Stress Tensor E?ects on Fluid Mechanics" in January 2010.

MODEL B-I FOR MACRO RECTANGULAR ELEMENT AND PROBLEMS OF INFLUENCE SURFACE FOR PLATE STRUCTURES

Model B-I for marco rectangular element is presented for the first time in this paper. To establish the influence surf ace for resultant R of bending plates, a number of generalized distributive loads q are defined. It is shown by numerical examples that Model B-I and the formula for the generalized distributive loads advanced in this paper are featured by high accuracy, low memory space and flexibility in practical application, and that they are especially effective for plate structures subject to moving loads, such as the two-dimensional continuous plates of highway bridges and the flat stabs in piled jetty engineering.

A statistical mechanics model of carbon nanotube macro-films

Carbon nanotube macro-films are two-dimensional films with micrometer thickness and centimeter by centimeter in-plane dimension.These carbon nanotube macroscopic assemblies have attracted significant attention from the material and mechanics communities recently because they can be easily handled and tailored to meet specific engineering needs.This paper reports the experimental methods on the preparation and characterization of single-walled carbon nanotube macro-films,and a statistical mechanics model on the deformation behavior of this material.This model provides a capability to optimize the synthesis process by comparing with the experiments.

Three-Dimensional Nonlinear Dynamic Model and Macro Control of Real Estate

In this paper, according to economics of real estate and macro-control theory, combine with the characteristics of the real estate market, macro-control of the real estate market is studied. After giving the dynamic model of three-dimensional nonlinear differential equations based on the total number of houses on the real estate business, the government’s averages housing investment funds and the standard price, systematically established the stability conditions of equilibrium point for this model. What’s more, through the use of extreme value analysis model, government funds have been invested in real estate business building devotion principles and the construction base of the real estate businessmen has also been estimated successfully. This provides the corresponding theoretical basis for government macro control policy-making.

AI作曲技术的创新实践与研究

随着大数据技术的完善,AI技术在音乐创作领域的应用日益广泛。AI作曲技术通过深度学习模型实现自动作曲,降低了音乐创作的门槛,使普通人也能参与专业创作。目前已有众多AI作曲平台及工具,如Magenta、Suno、天工SkyMusic等,本文首先分析了AI技术在音乐生成、风格迁移、音乐补全等方面的应用。其次,以上海音乐学院在教学实践中不断探索AI作曲的应用为例,展现其在非遗传承、声音疗愈等领域的强劲潜力。值得注意的是,虽然AI技术也对音乐艺术产生冲击,但音乐工作者应积极融合新技术,推动艺术与科技的共同发展。

A review of compact modeling for phase change memory

Phase change memory(PCM)attracts wide attention for the memory-centric computing and neuromorphic comput-ing.For circuit and system designs,PCM compact models are mandatory and their status are reviewed in this work.Macro mod-els and physics-based models have been proposed in different stages of the PCM technology developments.Compact model-ing of PCM is indeed more complex than the transistor modeling due to their multi-physics nature including electrical,thermal and phase transition dynamics as well as their interactions.Realizations of the PCM operations including threshold switching,set and reset programming in these models are diverse,which also differs from the perspective of circuit simulations.For the purpose of efficient and reliable designs of the PCM technology,open issues and challenges of the compact modeling are also discussed.

Multi-scale modeling of hemodynamics in the cardiovascular system

The human cardiovascular system is a closed- loop and complex vascular network with multi-scaled het- erogeneous hemodynamic phenomena. Here, we give a selective review of recent progress in macro-hemodynamic modeling, with a focus on geometrical multi-scale model- ing of the vascular network, micro-hemodynamic modeling of microcirculation, as well as blood cellular, subcellular, endothelial biomechanics, and their interaction with arter- ial vessel mechanics. We describe in detail the methodology of hemodynamic modeling and its potential applications in cardiovascular research and clinical practice. In addition, we present major topics for future study： recent progress of patient-specific hemodynamic modeling in clinical applica- tions, micro-hemodynamic modeling in capillaries and blood cells, and the importance and potential of the multi-scale hemodynarnic modeling.

A micromechanical damage model for rocks and concretes under triaxial compression

Based on analysis of deformation in an infinite isotropic elastic matrix containing an embedded elliptic crack, subject to far field triaxial compressive stress, the energy release rate and a mixed fracture criterion are obtained by using an energy balance approach. The additional compliance tensor induced by a single closed elliptic microcrack in a representative volume element and its in-plane growth is derived. The additional compliance tensor induced by the kinked growth of the elliptic microcrack is also obtained. The effect of the microcracks, randomly distributed both in geometric characteristics and orientations, is analyzed with the Taylor＇s scheme by introducing an appropriate probability density function. A micromechanical damage model for rocks and concretes under triaxial compression is obtained and experimentally verified.

基于改进分数去噪网络的铁路场景点云模型去噪方法

基于点云数据的逆向建模是铁路工程数字化发展的关键步骤,也是铁路数字孪生、结构健康监测等各种延伸应用的基础。为解决传统直接依赖无人机航测数据构建的点云模型存在精度低、可靠性差等问题,尤其是对于复杂的铁路场景,易导致模型与实际偏差过大,提出一种改进的分数去噪网络(Improved Score-based Denoised Network,ISDNet)。该网络在传统分数去噪网络的基础上构建了一套全新的编码器与解码器,在提高三维点云模型精度的同时,有效降低了计算复杂度和计算成本。该算法既减少了无人机逆向三维点云建模过程中由于环境扰动等因素产生的离散噪点,在铁路基础设施的结构细节处理上有较好的表现,将重建后的点云模型测量点坐标与全站仪测量的坐标进行了对比验证。实验验证结果表明,基于ISDNet网络去噪后的铁路场景三维模型的误差降低至原始模型的一半,各测量点间X方向的平均误差为5.67 mm,Y方向的平均误差为6.67 mm,Z方向的平均误差为6.83 mm。去噪后的三维点云模型有效减少了接触网、钢轨等细节数据的丢失,并显示出了更强的形状表征性,能够更清晰。本文所提方法能够实现铁路场景点云模型的高效去噪,并将模型精度进行提高,有效减少了点云模型中各构件细节的丢失,能够为相关的延伸应用提供可靠的技术支持。

三维机织复合材料的连接性能与失效机制

为了研究织物结构对三维机织复合材料连接性能的影响,设计了多层多向机织结构和层联机织结构复合材料,建立了开孔连接结构宏细观耦合分析模型,揭示了三维机织复合材料连接失效机制。研究表明:±45°纱所占的比例对复合材料机械连接的挤压强度具有重要影响,±45°纱线的引入,可以提高承载纱线的含量,能够有效改善孔边的应力集中现象;多层多向机织复合材料主要发生0°纱、90°纱和斜向纱的横纵向的损伤,损伤最初发生在孔边并逐渐扩展且呈对称分布,载荷的传递方向和损伤的传播方向呈现角度的特征。

泥岩卸荷损伤-水次序作用下的劣化规律研究

工程开挖建设导致软岩形成卸荷损伤,其在水-岩作用下的劣化特征与卸荷损伤程度密切相关。以巴东地区红层泥岩为研究对象,设计进行了泥岩卸荷损伤模拟试验,随后对卸荷损伤泥岩试样进行水-岩作用试验,结果显示:卸荷损伤导致泥岩局部矿物颗粒形态破坏、微裂缝发育,在后续水-岩作用下颗粒间胶结程度持续弱化,孔隙、裂缝进一步扩展。宏细观参数随水-岩作用时间的增长,其中质量m呈现先上升后骤然下降再趋于稳定的趋势,纵波波速P呈现先减少后上升的趋势,体积应变εv呈现逐渐增大的趋势,分形维数K呈逐渐增长的趋势;且各参数的增长速率均随卸荷损伤程度D的增大呈幂函数增加,当D≥0.49时,各参数的增长速率急剧增大;确定以质量、纵波波速、体积应变和分形维数作为与水反应系统的变量,并运用非线性动力学理论建立了水-岩作用下的泥岩劣化模型,并验证了模型的合理性。研究结果表明所建模型能表征卸荷损伤泥岩在水-岩作用下的宏细观特征参数变化趋势提供一定理论参考。

基于SBFEM的剪切型裂纹动态开裂模拟

剪切型断裂是岩土工程中常见的破坏模式,了解剪切破坏机理并准确预测剪切型裂纹的萌生、扩展过程对保障工程结构的安全性与稳定性具有重要意义.文章建立了基于比例边界有限元法(scaled boundary finite element methods,SBFEM)和非局部宏-微观损伤模型的剪切型裂纹动态开裂模拟方法,定义了基于偏应变概念的物质点对的正伸长量,可作为预测剪切型裂纹扩展行为的动态开裂准则,一点的损伤定义为该点影响域范围内连接的物质键损伤的加权平均值,而物质键的损伤则与基于偏应变概念的物质点对的正伸长量相关联,并引入能量退化函数建立结构域几何拓扑损伤与能量损失之间的关系,将拓扑损伤与应力应变联系起来,通过能量退化函数修正了SBFEM的刚度系数矩阵,得到了子域在损伤状态下的刚度矩阵,推导了考虑结构损伤的SBFEM动力控制方程,采用Newmark隐式算法对控制方程进行时间离散.最后,通过3个典型算例验证了建议的模型可较好地模拟剪切型断裂问题,能够很好地捕捉剪切型裂纹的扩展路径,并得到较为准确的载荷-位移曲线.

Investigation of Pile Construction and Productivity Loss: An Analysis of Macro Impact Factor

Pile foundations are challenging to build due to subsurface obstacles, contractor ignorance, and difficulties with site planning. Given the unpredictable environment of the construction site, productivity losses during pile work are to be thought possible. Prior to finishing a site pre-investigation, a foundation’s area is usually sampled for statistical reasons. There are studies on pile construction outside of Bangladesh that are supported by relevant empirical data in the literature. Since Bangladesh, which is regarded as a third-world country, is ignored in this regard, the literature currently available about pile building and the associated productivity loss is unable to provide adequate information or appropriate empirical data. Due to this pile-building sector in Bangladesh has been experiencing a decline in production for quite some time now. Before attempting to increase productivity in pile construction, it is essential to investigate the potential losses and the variables that might have an influence. This study aims to accomplish the following objectives: 1) identify the primary factors that have an impact on pile construction;2) develop an SVR model that accurately predicts productivity loss;and 3) figure out the projected loss by basing it on the historical scenario that is the most comparable to the current one. A Support Vector Regression (SVR) model was developed after a study of the relevant literature. This model enabled the collection of 110 pile building projects from five significant locations in Bangladesh. The model was constructed using a list of eight inputs in addition to a list of five macro elements (labor, management, environment, material, and equipment) (soil condition, pile type, pile material, project size, project location, pile depth, pile quantity, and equipment quantity). Using 10-way cross validation, the SVR achieves an accuracy of 87.2% in its predictions. On the basis of what has occurred in the past, we are able to estimate that there will be a loss of around 18.55 percent of the total output. A new perspective for engineers studying the delay factors with productivity loss is provided by the outcome of important tasks as it relates to loss in productivity and overall factors faced. In the building construction industry, effective management should place more emphasis on the correlation between productivity loss and the factors that cause it. Therefore, to represent the effect on productivity loss, real factors can be summed up as a decline in productivity loss. The findings of the study would urge specialists to concentrate on waste as a means of increasing overall production.

原油价格不确定性测度及其对宏观经济的非对称影响研究

有效测度原油价格不确定性并研究其对我国宏观经济的影响,具有重要的理论和现实意义。本文基于最小生成树模型,从全局视角衡量原油多元定价机制中195个影响因素的相对重要程度,并采用高维因子非预期条件波动率模型测度国际原油价格的不确定性。基于收敛交叉映射模型,本文对原油价格不确定性与宏观经济间的非线性因果关系进行识别,研究发现仅存在原油价格不确定性对固定资产投资、产出增速的单向因果关系。进一步地,在厘清原油价格不确定性对宏观经济影响机制的基础上,利用包含马尔可夫区制转移特征的向量自回归模型考察原油价格不确定性对我国宏观经济的影响,理论与实证结果均表明原油价格不确定性对我国宏观经济具有显著负向影响;在不同经济状态下,原油价格不确定性对投资、产出增速的影响具有非对称性。本研究为有效防范原油市场风险、保障能源安全和推动经济稳定增长提供了理论支持。