Management of Parametric Response in Design of Experiments

Routine applications of design of experiments (DOE) by non‐mathematicians assume that each response value is static in nature, i.e. with an expected value that is constant for a given set of input factor settings. When this assumption is not valid, it is important to capture the dynamic characteristics of the response for effective process or system characterization, monitoring, and control. With the purpose of recognizing the self‐changing nature of the response owing to factors other than those built into the DOE, thereby gaining a better ability to shape the behavior of the response, this paper describes the reasoning and procedure needed for such ‘parametric responses’, via common techniques of mathematical modeling and optimization. The procedure is intuitive but essential and useful in DOE studies as these become increasingly popular by practitioners in the context of improvement projects such as those related to Six Sigma or stand‐alone performance optimization initiatives. Copyright © 2013 John Wiley & Sons, Ltd.     

An Integrated Approach for Enhancing the Quality of the Product by Combining Robust Design and Customer Requirements

Enhancing the quality of the product has always been one considerable concern of production process management, and this subject gave way to implementing so many methods including robust design. In this paper, robust design utilizes response surface methodology (RSM) considering the mean and variance of the response variable regarding system design, parameter design, and tolerance design. In this paper, customer requirements and robust design are regarded simultaneously to achieve enriched quality. Subsequently, with a non‐linear programming, a novel method for integrating RSM and quality function deployment has been proposed to achieve robustness in design. The customer requirements are regarded in every stage of product development process meaning system design, parameter design and tolerance design. To validate the applicability of the proposed approach, it has been implemented in a real case of chemical industry. Research findings show that the proposed method is much better than other existing methods including MSE and dual response methods. According to this method, the resulted mean is better than MSE method, and more importantly, the variance of the process is approximately 14% and 10% lesser than dual response and MSE method. Copyright © 2013 John Wiley & Sons, Ltd.     

短波通信网在应急通信领域的应用

短波通信技术在通信系统中的广泛应用,为各个政府职能提供了巨大的方便,对短波通信的特点和组网方式进行了深入分析。针对应急通信部门的相关工作特点,阐述了建设短波通信网的必要性和可行性;并结合具体的应急通信部门的组成,提出了应急通信领域短波通信网的具体应用场景,给出了完整的系统组网方案,针对短波通信网与其他通信网络的互联互通问题,提出了具体解决方案,对人员防护提出了具体要求,最后对系统的日常维护和人员配备提出了具体要求。     

变截面压电悬臂梁系统的建模与实验验证

为对变截面压电悬臂梁系统的性能进行预测、分析和优化,该文对部分覆盖压电材料的悬臂梁数学进行了建模和分析。首先根据系统的动能、悬臂梁和压电片的热力学焓等能量关系的描述,应用拉格朗日方程得到系统的机电运动方程;再采用假设模态法并依据压电悬臂梁的边界条件和相容条件,给出系统的模态振型和自然频率的计算方法。实验结果表明,测量得到的一、二阶模态频率与理论模型计算的误差小于1%,测得的频率响应和理论预测吻合,提高了压电悬臂梁模型预测的精度。     

中继信道相位响应模型及其估计算法研究

中继能够提高信息传输质量及覆盖区域,是一种近年来得到迅速发展且前景广阔的无线通信技术。而性能优良的中继信道估计构成了改善通信环境的其他技术的基础前提。针对中继信道估计中的相位响应部分,首先建立了在任意信噪比条件下的相位噪声模型。考虑到估计过程快速的现实要求,通过将模型中原有复杂的表达噪声形式用高斯的方法近似化,得到了较为简洁的结果,并根据不同的简化形式给出对应的若干相位响应估计算法。为了比较这些算法之间的性能,重点推导了估计算法所能达到的CRLB。最后结合计算机数值仿真验证了结论的正确性。     

Dynamic denoising studies in wideband radio channel measurement and modeling

The fixed level and dynamic denoising method was studied based on indoor-to-outdoor measured channel impulse responses ORs） at 5.25 GHz with radio frequency （RF） 100 MHz bandwidth. It is found that the dynamic ranges, peak powers and noise floors of the IRs are with close correlations. The comparisons with different denoising methods are given by deriving the power delay profiles （PDPs）, root mean square （RMS） delay spread （RMS DS）, number of paths （NOPs） and Ricean K-factors. It is concluded that the traditional fixed level noise cut is under estimate of DS and NOPs. The Ricean K-factors are of little sensitive to noise cut irrespective of what kind of methods applied. The PDPs are not very sensitive to the fixed level noise cut, however, obvious changes can be found by dynamic noise cut. The dynamic noise cut is preferred when clear noise floors is observed and decided from the measured IRs, it＇s of importance in data post processing for wideband radio channel measurements as well as the relevant modeling work.     

Quasi-isotropic bending responses of metallic sandwich plates with bi-directionally corrugated cores

In order to reduce anisotropic behaviors of sandwich plates with open channel cores under the bending load, bi-directionally corrugated cores were introduced. Bi-directionally corrugated core has two additional design parameters related with a corrugation pass than uni-directionally corrugated core, so that its properties with respect to core orientations can be controlled. Sandwich plate with bi-directionally corrugated core is designed optimally so that beam buckling of face sheets is reduced drastically and anisotropic buckling behavior in the face sheets is minimized. The cores fabricated by a sectional forming process were bonded with face sheets by adhesive bonding. Three-point bending experiments were carried out with respect to core orientations. It has been shown from the experiments that sandwich plates with bi-directionally corrugated cores exhibit quasi-isotopic bending behaviors and structural performances in sandwich plates.     

Stochastic direct integration schemes for dynamic systems subjected to random excitations

In this work, a stochastic version of direct integration schemes is constructed, based on a general recursive state space formulation. The technique is applicable to evaluating the second order response statistics of systems subjected to non-stationary random excitations, and is potentially able to handle non-proportional damping. A specific group of these algorithms obtained using one of the most frequently used families of time stepping schemes is introduced. It is shown that statistics obtained for two multi-degree of freedom (MDOF) dynamic systems using the proposed method are in close agreement with those obtained from Monte Carlo simulation when a proper time step is used. Stability of the proposed scheme is systematically investigated and it is concluded that, for the response statistics to be bounded, the time step used in the algorithm has to lie within certain limits.     

Fracture of aluminium foam core sacrificial cladding subjected to air-blast loading

The effect of core density and cover plate thickness on the blast response of sacrificial cladding panels has been investigated through blast loading experiments and finite element modelling on structures with steel cover plates and aluminium foam cores. A range of foam core densities were examined, with 10%, 15% and 20% nominal relative densities. The cover plate thickness greatly influenced the response of the sacrificial cladding. Cover plates that were 2 mm thick exhibited significant permanent deformations and variable percentage crush across the section, whereas the 4 mm thick cover plates were more rigid causing the core to compress uniformly. Considerable fracture of the foam was observed after blast testing, particularly for the lower density foams. The effect of bonding the cover plate to the core was also examined. Numerical simulations of the experiments were performed using ABAQUS/Explicit to provide insight into the response mechanism. It was shown through the finite element simulations that tensile fracture of the foam occurred during the unloading phase of response and that adhesion of the cover plate to the foam caused higher levels of cracking. This was consistent with the experimental observations.