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11.
An important class of nonlinear control systems can be represented as the feedback interconnection of two parts: a linear time-invariant system and a block of decentralized nonlinearities. When the linear time-invariant part has a nontrivial feedthrough term or the nonlinearity has a feedback gain, control computation involves the online implementation of a multivariable algebraic loop which must be resolved at each sampling instant. The requirements for such online computation may result in several implementation issues, especially in real-time and embedded control applications. This paper considers the implementation of such algebraic loops arising from several input-constrained systems. The proposed solution algorithm is globally convergent for a very large class of feedthrough or feedback gains and shows promise for real-time and embedded control applications where a fast but approximate solution is of the essence. 相似文献
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Norbert Lindow Daniel Baum Steffen Prohaska Hans‐Christian Hege 《Computer Graphics Forum》2010,29(3):943-952
Molecular surfaces play an important role in studying the interactions between molecules. Visualizing the dynamic behavior of molecules is particularly interesting to gain insights into a molecular system. Only recently it has become possible to interactively visualize dynamic molecular surfaces using ray casting techniques. In this paper, we show how to further accelerate the construction and the rendering of the solvent excluded surface (SES) and the molecular skin surface (MSS). We propose several improvements to reduce the update times for displaying these molecular surfaces. First, we adopt a parallel approximate Voronoi diagram algorithm to compute the MSS. This accelerates the MSS computation by more than one order of magnitude on a single core. Second, we demonstrate that the contour‐buildup algorithm is ideally suited for computing the SES due to its inherently parallel structure. For both parallel algorithms, we observe good scalability up to 8 cores and, thus, obtain interactive frame rates for molecular dynamics trajectories of up to twenty thousand atoms for the SES and up to a few thousand atoms for the MSS. Third, we reduce the rendering time for the SES using tight‐fitting bounding quadrangles as rasterization primitives. These primitives also accelerate the rendering of the MSS. With these improvements, the interactive visualization of the MSS of dynamic trajectories of a few thousand atoms becomes for the first time possible. Nevertheless, the SES remains a few times faster than the MSS. 相似文献
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将差分功耗分析的汉明重量模型与传统的代数攻击相结合,实现了针对128位密钥的AES密码算法第一轮的功耗代数攻击.在攻击实验中,改进了汉明重量函数,并证明了利用此函数能够通过进一步计算的相关系数r明显区分出正确密钥字节与错误密钥字节,在最短时间内获得正确的真实的全部密钥字节,对比其他同类研究更具适用性和高效性. 相似文献
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From the motivation of algebraic attacks on stream and block ciphers,the concept of algebraic immunity(AI) of a Boolean function was introduced and studied extensively.High algebraic immunity is a necessary condition for resisting algebraic attacks.In this paper,we give some lower bounds on the algebraic immunity of Boolean functions.The results are applied to give lower bounds on the AI of symmetric Boolean functions and rotation symmetric Boolean functions.Some balanced rotation symmetric Boolean functions with their AI near the maximum possible value「n/2」are constructed. 相似文献
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Qualitative algebraic equations are the basis of qualitative simulation,which are used to express the dynamic behavior of steady-state continuous processes.When the values and operation of qualitative variables are redefined,qualitative algebraic equations can be transformed into signed direct graphs,which are frequently used to predict the trend of dynamic changes.However,it is difficult to use traditional qualitative algebra methods based on artificial trial and error to solve a complex problem for dynamic trends.An important aspect of modern qualitative algebra is to model and characterize complex systems with the corresponding computer-aided automatic reasoning.In this study,a qualitative affection equation based on multiple conditions is proposed,which enables the signed di-rect graphs to describe complex systems better and improves the fault diagnosis resolution.The application to an industrial case shows that the method performs well. 相似文献
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研究受有多点横向非定常约束梁的动态响应问题。利用横向非定常约束为周期函数梁的微分代数方程的线性特点,确定出多基频周期性非定常约束激励下梁稳态响应的解析解;利用截断模态的微分代数方程确定出受有横向非定常约束梁的瞬态响应。为此,首先利用无阻尼截断模态微分代数方程的齐次形式,将欧拉-伯努利梁的等效多跨梁模态表示为简单边界条件下模态函数的线性组合,再利用得到的模态函数与位移影响函数重新将微分代数方程表示为常微分方程的形式,进而得到横向非定常约束作用下梁的瞬态响应解的积分形式。在此过程中,研究了微分代数方程齐次式的特征值及其数量、求解方法等相关问题。通过单点多频率的横向非定常约束作用的梁及多点单频横向非定常约束作用梁的算例,重点分析了非定常约束位置与基频对梁稳态响应的影响。结果表明:在欠阻尼下,两种梁模态响应的极大值均在等效多跨梁的各个主频附近;单点横向非定常约束作用响应极小值在简单边界条件梁的各个主频附近,而多点横向非定常约束作用梁响应极小值的分布比较复杂。算例也说明了所提出的方法是正确、有效的。 相似文献
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分类算法是机器学习和数据分析中重要的算法.当需要对分类算法本身以及算法的输入数据进行隐私保护时,就出现了分类算法安全评估问题.针对现有的分类算法安全评估协议效率较低的问题,文章给出了一种基于代数决策图和线性多分支程序的解决方案.首先,设计了基于代数决策图的安全函数评估协议,用以安全评估决策函数;其次,引入了线性多分支程序的概念,用其对分类算法进行表示.最后,借助线性多分支程序和基于代数决策图的安全函数评估协议,给出了一个私有线性多分支程序的安全评估协议.对新的协议的正确性和安全性进行了分析和证明.实验数据表明,与原有的解决方案相比,新的协议在效率上有明显的提高. 相似文献
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