信道受限的参数不确定网络控制系统滤波器设计

针对存在信道受限和外部信号干扰的参数不确定网络控制系统,研究了一类H_(∞)滤波器设计问题,以提高控制系统鲁棒性.使用独立伯努利序列构建信道受限网络通信模型,运用参数分离法分解控制系统矩阵中不确定参数项;在此基础上,通过构建含有两个子系统的离散切换系统描述滤波误差系统,利用李雅普诺夫函数和离散切换系统理论证明滤波误差系统渐近稳定并具有H_(∞)性能指标,通过线性矩阵不等式给出滤波器参数求解的方法.实验结果表明最优性能指标γ^(*)=1.6294,具有较低的保守性.所设计参数不确定的H_(∞)滤波器较好的跟踪控制系统,消除外部信号的干扰.

变式中层进,层进中拓展——高三专题课“函数中的恒成立问题、有解问题”的教学思考

函数中的“恒成立问题、有解问题”其核心就是参数问题,参数是指有别于常数与变数的一种中间状态的数,同时它又兼有常数和变数的双重特征。正因为其在“变”与“不变”之间的这种游离状态,所以要在变式训练中达成难点突破。

Amenability to dry processing of high ash thermal coal using a pneumatic table

High ash thermal coal from India was used to conduct the dry processing of fine coal using a pneumatic table to evolve a techno-economically novel technique. The fine as-received sample having 55.2g ash was subjected to washability studies at variant densities from 1.4 to 2.2 to assess the amenability to separa- tion. The experiments were conducted using a central composite design for assessing the interactive effects of the variable parameters of a pneumatic table on the product yield and ash content. The performance of the pneumatic table was analyzed in terms of clean coal yield, recovery of combustibles, separation efficiency （Esp） and useful heat value of clean coal. The combustibles of clean coal obtained through a single stage operation at 35% and 38.7% ash were 40% and 63% respectively. However, the two stage processing was more effective in reducing the ash content in the clean coal. The rougher concentrate generated at higher ash level was subsequently processed in different conditions at 35% ash level, and 58g combustibles could be recovered. Hence, two stage processing increases the combustibles by 18 units and the useful heat value of clean coal increases from 1190 kcal/kg to 3750 kcal/kg.

Spatiotemporal distribution model for zinc electrowinning process and its parameter estimation

This paper focuses on the distributed parameter modeling of the zinc electrowinning process(ZEWP)to reveal the spatiotemporal distribution of concentration of zinc ions(CZI)and sulfuric acid(CSA)in the electrolyte.Considering the inverse diffusion of such ions in the electrolyte,the dynamic distribution of ions is described by the axial dispersion model.A parameter estimation strategy based on orthogonal approximation has been proposed to estimate the unknown parameters in the process model.Different industrial data sets are used to test the effectiveness of the spatiotemporal distribution model and the proposed parameter estimation approach.The results demonstrate that the analytical model can effectively capture the trends of the electrolysis reaction in time and thus has the potential to implement further optimization and control in the ZEWP.

Influence of preload discreteness on air-operated separation process of low-shock separation device

To investigate the influence of design parameters on the performance of separation device,the structure and air-operated test of a low-shock separation device are introduced and analyzed in this paper.According to the law of energy conservation and aerodynamics,a mathematical model is built.Because the preload used to ensure the connection reliability has the discreteness,which will influence the separation process,the influence of preload discreteness on the air-operated separation process is simulated and tested.Simulation results are consistent with the experimental results.It is shown that the change of preload has an obvious influence on the separation process.The study is useful for the design and optimization of separation device.

运用端点效应理论高效处理导数问题

高考中的含参恒成立问题一直是高考难点,破解难度较大.近年来高考以及全国各地的模拟题中都出现了大量含参数恒成立问题,我们经常采用变量分离,等价转换等方法来进行解题.在使用这些做法解题中我们时常会遇到分类讨论情况多,我们可以说是不胜其烦,很难摆脱计算量大的困局,甚至最后不了了之,造成得分率较低的实际情况.本文结合笔者教学实际,发现在很多时候我们使用端点效应来解题效率会高得多,能够有效避免不必要的分层讨论,达到耗时少,得分多的效果.

Estimation of the J-resistance curve for Cr2Ni2MoV steel using the modified load separation parameter S_(pb) method

Based on load separation theory, the load separation parameter Spb method is an effective approach for estimating the J-resistance curve from records of load versus displacement directly, using one sharp cracked specimen and an additional reference blunt cracked specimen. However, the effect of the reference blunt cracked specimen on J-resistance determination was not explicitly considered in past work. In this paper, a modified load separation parameter Spb method was developed to eliminate this effect, and then a unique estimation of instantaneous crack length for one sharp cracked specimen could be obtained. Furthermore, a forced blunting calibration method was also adopted to determine the instantaneous crack length in the load inseparable region, referring to a normalization method. Experiments on steam turbine rotator steel Cr2Ni2MoV were carried out to estimate J-resistance curves using an unloading compliance method. By removing unload and reload data from load-displacement records, the J-resistance curve for the same sharp cracked specimen was estimated using the modified separation parameter Spb method. The results indicate that the modified Spb method completely eliminates the effect of the reference blunt cracked specimen on the instantaneous crack length determination of the sharp cracked specimen. However, different J-resistance curves in a small range of crack extension are present when different blunting coefficients are used in the blunting line equation. The J-resistance curve obtained from the modified Spb method agrees well with that obtained from the compliance method.

Pose optimization based on integral of the distance between line segments

In this paper, new solutions for the problem of pose estimation from correspondences between 3D model lines and 2D image lines are proposed. Traditional line-based pose estimation methods rely on the assumption that the noises(perpendicular to the line) for the two endpoints are statistically independent. However, these two noises are in fact negatively correlated when the image line segment is fitted using the least-squares technique. Therefore, we design a new error function expressed by the average integral of the distance between line segments. Three least-squares techniques that optimize both the rotation and translation simultaneously are proposed in which the new error function is exploited. In addition, Lie group formalism is utilized to describe the pose parameters, and then, the optimization problem can be solved by means of a simple iterative least squares method. To enhance the robustness to outliers existing in the match data, an M-estimation method is developed to convert the pose optimization problem into an iterative reweighted least squares problem. The proposed methods are validated through experiments using both synthetic and real-world data. The experimental results show that the proposed methods yield a clearly higher precision than the traditional methods.

An ultra-accurate dynamic isogeometric analysis with higher order mass formulation

An ultra-accurate isogeometric dynamic analysis is presented.The key ingredient of the proposed methodology is the development of isogeometric higher order mass matrix.A new one-step method is proposed for the construction of higher order mass matrix.In this approach,an adjustable mass matrix is formulated through introducing a set of mass parameters into the consistent mass matrix under the element mass conservation condition.Then the semi-discrete frequency derived from the free vibration equation with the adjustable mass matrix is served as a measure to optimize the mass parameters.In 1D analysis,it turns out that the present one-step method can perfectly recover the existing reduced bandwidth mass matrix and the higher order mass matrix by choosing different mass parameters.However,the employment of the proposed one-step method to the2D membrane problem yields a remarkable gain of solution accuracy compared with the higher order mass matrix generated by the original two-step method.Subsequently a full-discrete isogeometric transient analysis algorithm is presented by using the Newmark time integration scheme and the higher order mass matrix.The full-discrete frequency is derived to assess the accuracy of space-time discretization.Finally a set of numerical examples are presented to evaluate the accuracy of the proposed method,which show that very favorable solution accuracy is achieved by the present dynamic isogeometric analysis with higher order mass formulation compared with that obtained from the standard consistent mass approach.