Decision-making and biases in cybersecurity capability development: Evidence from a simulation game experiment

We developed a simulation game to study the effectiveness of decision-makers in overcoming two complexities in building cybersecurity capabilities: potential delays in capability development; and uncertainties in predicting cyber incidents. Analyzing 1479 simulation runs, we compared the performances of a group of experienced professionals with those of an inexperienced control group. Experienced subjects did not understand the mechanisms of delays any better than inexperienced subjects; however, experienced subjects were better able to learn the need for proactive decision-making through an iterative process. Both groups exhibited similar errors when dealing with the uncertainty of cyber incidents. Our findings highlight the importance of training for decision-makers with a focus on systems thinking skills, and lay the groundwork for future research on uncovering mental biases about the complexities of cybersecurity.     

Event-by-event simulation of a quantum delayed-choice experiment

The quantum delayed-choice experiment of Tang et al. (2012) is simulated on the level of individual events without making reference to concepts of quantum theory or without solving a wave equation. The simulation results are in excellent agreement with the quantum theoretical predictions of this experiment. The implication of the work presented in the present paper is that the experiment of Tang et al. can be explained in terms of cause-and-effect processes in an event-by-event manner.     

Generating different profiles of gradient concentrations inside a gel-filled chamber: design and simulation

Spatial and temporal in vivo variations of biochemical cues affect the cellular behavior and responses in live systems. To study the biological phenomena, an appropriate environment that could facilitate generation of gradients within extracellular spaces is highly desirable. Microfluidic platforms have been widely used in cellular biology research because of their ability to mimic in vivo environments. This paper discusses the design and simulation of a microfluidic device to generate predictable profiles of various stable gradient concentrations in a hydrogel-filled chamber. Simulations have been carried out by using Coventorware for steady state, transient mode and overlapping gradients to fine-tune the design parameters. The design will have applications in three-dimensional biological cell cultures and studies.     

聚能装药侵彻混凝土数值模拟

采用自主开发的EXPLOSION-2D软件对不同锥角药型罩结构的聚能装药成型进行数值模拟,结果表明:随着药型罩锥角的增加,侵彻体的头部速度和长度均不断减小,导致其侵彻能力下降,但侵彻体直径不断增加使得其侵彻孔径增加.因此,设计一种在炸药内开槽的装药结构,并对炸药内部开槽位置以及槽的高度和宽度对侵彻体侵彻能力的影响进行数值模拟,获得其对侵彻体侵彻性能的影响规律.结果表明:开槽位置以及槽的高度和槽的宽度均存在一个最佳值,使得侵彻体侵彻混凝土性能达到最佳,由此说明合理的设计开槽结构能够有效提升侵彻体侵彻混凝土的有效深度.     

Predictable behavior during contact simulation: a comparison of selected physics engines

Contact behaviors in physics simulations are important for real‐time interactive applications, especially in virtual reality applications where user's body parts are tracked and interact with the environment via contact. For these contact simulations, it is ideal to have small changes in initial condition yield predictable changes in the output. Predictable simulation is key for success in iterative learning processes as well, such as learning controllers for manipulations or locomotion tasks. Here, we present an extensive comparison of contact simulations using Bullet Physics, Dynamic Animation and Robotics Toolkit (DART), MuJoCo, and Open Dynamics Engine, with a focus on predictability of behavior. We first tune each engine to match an analytical solution as closely as possible and then compare the results for a more complex simulation. We found that in the commonly available physics engines, small changes in initial condition can sometimes induce different sequences of contact events to occur and ultimately lead to a vastly different result. Our results confirmed that parameter settings do matter a great deal and suggest that there may be a trade‐off between accuracy and predictability. Copyright © 2016 John Wiley & Sons, Ltd.     

玫瑰线轨迹模型及其仿真实验

建立了玫瑰线轨迹模型,对模型进行了理论证明并使用Mathematica软件对其做了仿真实验。理论与实验均表明,当模型中参数k=1+n/1-n时,即可得到玫瑰线轨迹ρ=acosnθ。该模型从运动的角度揭示了玫瑰线的生成规则,为机械绘制玫瑰线提供了理论依据。     

皮卫星在轨能量平衡仿真及实验

以往对皮卫星的能量平衡分析,都仅仅建立在仿真的基础上.针对皮卫星的实际情况以及特点,改进了电源系统的仿真建模,建立了分流器件的真实模型,实时计算太阳电池阵、蓄电池和负载的在轨工作参数以及分析实时的电压平衡和能量平衡,得出了真实的能量平衡仿真模型.为了给能量平衡分析提供更加有力的依据,并验证能量平衡仿真,提出了一种基于实物的能量平衡实验方法,并设计出太阳电池模拟器.通过对卫星母线电压、锂离子电池电量的仿真结果和实验结果进行对比,使能量平衡分析得到了验证,也表明浙江大学皮卫星的能量条件可以保证整星的能量平衡.     

Finite dose percutaneous drug absorption: a BASIC program for the solution of the diffusion equation

A BASIC program to obtain the solution for the diffusion equation describing the finite dose percutaneous absorption pharmacokinetics is shown. Drug amount in the solution matrix, Av, that in the skin which is regarded as a simple diffusion membrane. As, and the drug flux from the skin which is provided by the local circulation per unit area, J, and the blood drug concentration. C, expressed as functions of time are obtained using Fourier series. Usually, a small number (less than 10) of series is enough to obtain the accurate values for Av, As, J, and C. It is also shown that the solution of the diffusion equation reported previously for the specific case where both the diffusion coefficient of a drug through the vehicle and skin-capillary clearance are very large is expressed as a limit.     

Finite element simulation of dynamic strain-localization: A multi-scale problem

A Finite Element procedure for the post-localization analysis of elasto-plastic solids is developed. To ensure unique solutions, the Duvaut-Lions visco-plastic regularization procedure [1] is implemented. A bifurcation analysis of the underlying backbone elasto-plastic material is performed to locate the shear band and to define its orientation. The width of the shear band is assumed to be much smaller than the characteristic element size h. To capture the structure of the shear band, the kinematics is enriched by incorporating additional degrees of freedom in a patch within the element and overlying the shear band. Within each localized element, compatibility is ensured between the strain fields inside and outside the patch. A Petrov-Galerkin type procedure to account for the narrow width of the patch is implemented. The results indicate formation of mesh and patch invariant shear bands. Finally, the effects of varying material parameters are studied. The results are found to be consistent with known localization characteristics.     

Finite element response sensitivity analysis: a comparison between force-based and displacement-based frame element models

This paper focuses on a comparison between displacement-based and force-based elements for static and dynamic response sensitivity analysis of frame type structures. Previous research has shown that force-based frame elements are superior to classical displacement-based elements enabling, at no significant additional computational costs, a drastic reduction in the number of elements required for a given level of accuracy in the simulated response. The present work shows that this advantage of force-based over displacement-based elements is even more conspicuous in the context of gradient-based optimization methods, which are used in several structural engineering sub-fields (e.g., structural optimization, structural reliability analysis, finite element model updating) and which require accurate and efficient computation of structural response and response sensitivities to material and loading parameters. The two methodologies for displacement-based and force-based element sensitivity computations are compared. Three application examples are presented to illustrate the conclusions. Material-only non-linearity is considered. Significant benefits are found in using force-based frame element models for both response and response sensitivity analysis in terms of trade-off between accuracy and computational cost.     

一个新类Lorenz混沌系统的动力学分析及电路仿真

提出了一个新的三维自治类Lorenz系统.理论分析了该系统的动力学特性,并通过数值计算分析了系统在平衡点处的稳定性,以及产生Hopf分岔的条件.通过计算系统的时间序列的Lyapunov指数谱、Lya-punov维数、分岔图、Poincar啨截面图等研究了系统的动力学特性.最后对该系统的一个混沌吸引子进行了实际电路的设计与仿真模拟.     

基于UDP协议的NAT穿透技术研究与仿真

NAT穿透技术能够有效解决由于IP地址短缺和路由表增大造成的用户接入困难的问题,可缓解因网络地址的严重消耗造成的IPv4资源稀缺的情况。针对这种情况进行了基于UDP协议的NAT穿透技术研究与仿真。首先分析NAT穿透的类型及各自的原理,提出对于NAT穿透相对有效的UDP打洞方案,然后通过穿透原理得出算法结构流程,最后在VC++环境下进行仿真实验。实验结果表明,该算法结构能够有效地实现NAT穿透目的,而且具有可拓展性,可在较多情况下适用。     

Finite element simulation of stretch forging using a mesh condensation method

In order to reduce the computation time of finite element simulations of stretch forging process,a mesh condensation method is presented and applied to a three-dimensional rigid-viscoplastic finite element program.In this method,a conventional mesh for the whole zone of a workpiece is condensed to a computational mesh for the active deformation zone.Two vital problems are solved,which are automatic construction of the computational mesh and treatment of interfaces between the deformation zone and the rigid ...     

HZSM-5中水吸附行为的实验与分子模拟

利用智能重量分析仪(IGA—003,HIDEN)测定了298K条件下水蒸汽在HZSM-5型分子筛中的吸附等温线。并采用巨正则系综Monte Carlo模拟方法(GCMC)研究了水在HZSM—5型分子筛中的吸附等温线,计算结果与实验结果吻合较好。分子模拟计算得到的水分子的微观吸附性质表明水分子吸附在氢离子和铝原子的周围,这是因为水分子是极性分子,分子筛上的氢在库仑力的作用下会与水分子发生强的相互作用,并导致分子筛骨架上的硅铝比与水分子的吸附量之间存在线性关系。计算结果还表明水的吸附热与H_2O/Al之间存在线性关系。     

漏磁检测的仿真和实验研究

根据检测得到漏磁信号重构出缺陷的外形轮廓,需要建立完整的缺陷模型数据库。首先,在搭建的漏磁信号的检测平台中,由上位机控制数采卡采集由霍尔传感器阵列转换得到的多通道漏磁信号,并实时显示采集到的缺陷信号。再通过有限元分析软件ANSYS对缺陷建模仿真,并计算分析出缺陷的磁力线分布。分析对比两组实验数据显示,两组数据吻合的很好,可以用ANSYS仿真的数据来建立数据库。     

Finite element simulation of robotic origami folding

In this paper, we focus on some aspects of the finite element simulations of robotic paper folding and the reconstruction of models from the origami crease patterns by the robot arms. The paper highlights the simulation problems, which should be solved in developing our recent study in mechanical and geometrical design of the origami-performing robot. The basic premise underlying the study is that folding operations with the origami crease patterns are considered as the functions of the mechanical systems such as a robot. Manipulations with the foldable objects, such as a sheet of paper (the origami crease pattern), by the robot arms in the simulation environment lead to understanding the design of the origami-performing robot without testing physical prototypes at each design stage. In this case, dynamic and kinematic behavior of the robot arms in forming the 3D origami objects is modelled by using the finite element method (FEM) in LS-DYNA solver. For simulating, two forms of origami are considered: flexible, if bending is used for paper folding, and rigid, if origami patterns are considered as the kinematic systems. Results of the simulation are presented and provided by the illustrations.     

Model-independent comparison of simulation output

Computational models of complex systems are usually elaborate and sensitive to implementation details, characteristics which often affect their verification and validation. Model replication is a possible solution to this issue. It avoids biases associated with the language or toolkit used to develop the original model, not only promoting its verification and validation, but also fostering the credibility of the underlying conceptual model. However, different model implementations must be compared to assess their equivalence. The problem is, given two or more implementations of a stochastic model, how to prove that they display similar behavior? In this paper, we present a model comparison technique, which uses principal component analysis to convert simulation output into a set of linearly uncorrelated statistical measures, analyzable in a consistent, model-independent fashion. It is appropriate for ascertaining distributional equivalence of a model replication with its original implementation. Besides model-independence, this technique has three other desirable properties: a) it automatically selects output features that best explain implementation differences; b) it does not depend on the distributional properties of simulation output; and, c) it simplifies the modelers’ work, as it can be used directly on simulation outputs. The proposed technique is shown to produce similar results to the manual or empirical selection of output features when applied to a well-studied reference model.     

大马力拖拉机驱动桥有限元分析及试验研究

驱动桥作为拖拉机的传动和承载部件,受力较大且使用频繁,通过对桥壳 模型的有限元分析,可以验证设计的安全性并可以通过分析结果来改进设计。首先采用Pro/E 对拖拉机驱动桥壳、转向节、半轴进行三维建模并导入Hypermesh 中进行有限元分析的前 处理工作,然后将导出的文件输入ANSYS 中进行有限元分析。最后通过桥壳的刚度试验和 疲劳试验验证了此驱动桥的安全性,并给出了改进意见。