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71.
In the present work, mathematical models of three important casting processes are considered namely squeeze casting, continuous casting and die casting for the parameters optimization of respective processes. A recently developed advanced optimization algorithm named as teaching–learning-based optimization (TLBO) is used for the parameters optimization of these casting processes. Each process is described with a suitable example which involves respective process parameters. The mathematical model related to the squeeze casting is a multi-objective problem whereas the model related to the continuous casting is multi-objective multi-constrained problem and the problem related to the die casting is a single objective problem. The mathematical models which are considered in the present work were previously attempted by genetic algorithm and simulated annealing algorithms. However, attempt is made in the present work to minimize the computational efforts using the TLBO algorithm. Considerable improvements in results are obtained in all the cases and it is believed that a global optimum solution is achieved in the case of die casting process. 相似文献
72.
73.
《Communications in Nonlinear Science & Numerical Simulation》2014,19(6):2060-2070
The parameter space of the two dimensional Rulkov chaotic neuron model is taken into account by using the qualitative analysis, the co-dimension 2 bifurcation, the center manifold theorem, and the normal form. The goal is intended to clarify analytically different dynamics and firing regimes of a single neuron in a two dimensional parameter space. Our research demonstrates the origin that there exist very rich nonlinear dynamics and complex biological firing regimes lies in different domains and their boundary curves in the two dimensional parameter plane. We present the parameter domains of fixed points, the saddle-node bifurcation, the supercritical/subcritical Neimark–Sacker bifurcation, stability conditions of non hyperbolic fixed points and quasiperiodic solutions. Based on these parameter domains, it is easy to know that the Rulkov chaotic neuron model can produce what kinds of firing regimes as well as their transition mechanisms. These results are very useful for building-up a large-scale neuron network with different biological functional roles and cognitive activities, especially in establishing some specific neuron network models of neurological diseases. 相似文献
74.
对于带约束条件和多余参数的两个线性模型e1=L(X1β+Z1γ,V1,L1)和d2=L(X2β+Z2δ,V2,L2),其中V1和V2是已知对称的正定矩阵,γ和δ是多余参数,L1和L2是已知的约束矩阵,文中给出了一种新的比较准则,并得到了几个充要条件。 相似文献
75.
Jianjun Gao 《Solid-state electronics》2011,63(1):42-48
A new method for the determination of the four noise parameters of the metal oxide semiconductor field effect transistors (MOSFETs) based on the noise figure measurement system without microwave tuner is presented. The noise parameters are determined based on a set of analytical expressions of noise parameters by fitting the measured noise figure of the active device. These expressions are derived from an accurate small signal and noise equivalent circuit model, which takes into account the substrate parasitics, pad capacitances, and series inductances. On-wafer experimental verification is presented and a comparison with tuner based method is given. Good agreement is obtained between simulated and measured results for 0.5 × 5 × 16 μm, 0.35 × 5 × 16 μm and 0.18 × 5 × 16 μm (gate length × number of gate fingers × unit gate width) MOSFETs. 相似文献
76.
In parameter space of nonlinear dynamical systems, windows of periodic states are aligned following the routes of period-adding configuring periodic window sequences. In state space of driven nonlinear oscillators, we determine the torsion associated with the periodic states and identify regions of uniform torsion in the window sequences. Moreover, we find that the measured torsion differs by a constant between successive windows in periodic window sequences. Finally, combining the torsion-adding phenomenon, reported in this work, and the known period-adding rule, we deduce a general rule to obtain the asymptotic winding number in the accumulation limit of such periodic window sequences. 相似文献
77.
78.
1.引 言由多孔介质的渗流理论,二维稳态各向异性介质的渗流问题满足下列偏微分方程 -div(u(x,y)(?)u(x,y))=f(x,y),(x,y)∈Ω(?)R2, (1.1) 相似文献
79.
拓扑指数或分子连通性指数法在研究有机化合物结构与性能关系方面,已作了大量工作,并得到了广泛的应用。拓扑指数只与分子的几何结构有关,而不考虑原子的性质;键参数法虽然研究无机化合物结构与性能方面已获得了巨大的成功,但键参数法只考虑原子的性质,而不考虑分子的几何结构,使它们的应用受到了一定的限制。Berysz,张宏光和辛厚文等在将键参数和拓扑指数结合起来方面和了有益的尝试。本文提出了一种将分子的几何结构与组成分子的原子性质较好结合起来的键参数拓扑指数。 相似文献
80.
优先队列控制模型参数优化 总被引:1,自引:0,他引:1
文献[1]中提出了一种新交换结构模型──优先队列控制(PQC)模型.本文主要讨论如何设定该模型的参数,这是一个二指标的多目标优化问题首先,本文假设两类到达业务分别为两个相互竞争的局中人,进而将这个多目标优化问题转化为一个合作对策问题来求解;然后,运用Kuhn-Tucker条件求出效用空间和Pareto边界,再用一类协商规则解得一组使得全局能具有较好满意程度的理性解;最后给出了一些数值计算的例子进行说明 相似文献