Robustness of asymptotic accelerated life test plans to small‐sample settings

Much of the statistical literature on optimal test planning for accelerated life testing utilize asymptotic methods to derive optimal test plans. While sufficient effort is made to assess the robustness of these test plans to the choice of design parameters and distribution assumptions, there is very little literature on the performance of asymptotic test plans relative to small samples (on the order of 10‐15 samples). An alternative concern is that the asymptotic test plans may not necessarily be the true “optimal” test plan for a given sample size. The purpose of this research is to present exact or “near‐exact” methods for developing test plans and compare the performance of these test plans with corresponding asymptotic test plans in small‐sample settings. The optimal location of design points and sample allocation is determined using each method for lognormal and Weibull lifetime distributions with both complete and Type 1 right‐censored data under two selected acceleration factor models. The investigations reveal that asymptotic test plans tend to corroborate quite well with exact test plans and thus are suitably robust to small‐sample settings in terms of optimal variance.     

Order-of-addition experiments: A review and some new thoughts

Abstract

The study of order-of-addition (OofA) experiments is prevalent in many scientific and industrial areas. The statistical design of experiments (DOE) will considerably improve the efficiency of OofA experiments. Designing and modeling the OofA experiments have increasingly received a great deal of attention. In this article, we review the latest work on the design and model of OofA experiments, and introduce some new thoughts. We believe that this article will motivate fruitful applications in real OofA experiments as well as future developments in the methodology.     

Environmental and energy life cycle analyses of passenger vehicle systems using fossil fuel-derived hydrogen

Hydrogen energy utilization is expected due to its environmental and energy efficiencies. However, many issues remain to be solved in the social implementation of hydrogen energy through water electrolysis. This analyzes and compares the energy consumption and GHG emissions of fossil fuel-derived hydrogen and gasoline energy systems over their entire life cycle. The results demonstrate that for similar vehicle weights, the hydrogen energy system consumes 1.8 MJ/km less energy and emits 0.15 kg-CO 2 eq./km fewer GHG emissions than those of the gasoline energy system. Hydrogen derived from fossil fuels may contribute to future energy systems due to its stable energy supply and economic efficiency. Lowering the power source carbon content also improved the environmental and energy efficiencies of hydrogen energy derived from fossil fuels.     

基于区间犹豫模糊语言集的水资源多目标决策

以鄂北水资源配置工程为对象,研究大型调水工程背景下的多水源多目标优化配置。将鄂北地区水库分为充蓄水库、补偿水库与在线水库等3类,根据各类水库特点对鄂北水资源配置工程进行系统概化,建立以年缺水量最小和调水成本最低为目标函数的多水源多目标优化配置模型。采用权重系数法进行求解得到非劣解集。最后采用基于区间犹豫模糊语言与TOPSIS的多目标决策方法对各方案的缺水量与调水量作出评价并遴选出最优方案。研究结果表明:对鄂北水资源配置工程而言,缺水量与调水量的权重比为7∶3的方案综合评价最优,重视缺水的同时兼顾调水成本;基于区间犹豫模糊语言集与TOPSIS的水资源多目标决策方法经本文实例验证具有较高的稳定性与可行性。     

平板显示基板玻璃窑炉烟气脱硝技术探究

随着生态环境意识的加强和环保治理力度的提升,平板玻璃窑炉烟气氮氧化物治理已经全面落实。而由于平板显示基板玻璃窑炉烟气性质的独特性,其脱硝技术路线的选择也取决于不同地区氮氧化物排放浓度的限值差异。详细介绍了选择性催化还原法(SCR)、选择性非催化还原法(SNCR)和逆向流选择性催化还原法(CSCR)三种脱硝技术并对比了三者之间在脱硝效率、反应温度、初始投资、全生命周期成本的差异。同时,对未来的发展应用进行了展望。     

混菌矿化增强再生粗骨料的物理力学性能

为克服单一微生物培养成本高且矿化鲁棒性不足的缺陷，提出了一种混菌矿化增强再生粗骨料物理力学性能的方法.通过筛选矿化效率较高的好氧嗜碱混菌，考察了混菌矿化对再生粗骨料物理力学性能和混凝土抗压强度的影响.结果表明：相同增强时间下，混菌比纯菌呈现出更优异的矿化增强效果；随着混菌矿化增强时间的延长，再生粗骨料吸水率和压碎指标呈现出先减小后增大的趋势，最优增强时间为15 d；采用矿化增强再生粗骨料制备的再生混凝土抗压强度提高幅度达到22.1%.     

Fabrication,permeation, and corrosion stability measurements of silica membranes for HI decomposition in the thermochemical iodine–sulfur process

In this study, a corrosion-stable silica membrane was developed to be used in H₂ purification during the hydrogen iodide decomposition (2HI → H₂ + I₂), which is a new application of the silica membranes. From a practical perspective, the membrane separation length was enlarged up to 400 mm and one end of the membrane tubes was closed to avoid any thermal variation along the membrane length and sealing issues. The silica membranes consisted of a three-layer structure comprising a porous α-Al₂O₃ ceramic support, an intermediate layer, and a top silica layer. The intermediate layer was composed of γ-Al₂O₃ or silica, and the top silica layer that is H₂ selective was prepared via counter-diffusion chemical vapor deposition of a hexyltrimethoxysilane.To the best of our knowledge, this is the first report of 400-mm-long closed-end silica membranes supported on Si-formed α-Al₂O₃ tubes produced via chemical vapor deposition method. A 400-mm-long closed-end membrane using a Si-formed α-Al₂O₃ tube exhibited a higher H₂/SF₆ selectivity of 1240 but lower H₂ permeance of 1.4 × 10⁻⁷ mol Pa⁻¹ m⁻² s⁻¹ with compared with the membrane using a γ-Al₂O₃-formed α-Al₂O₃ tube (907 and 5.6 × 10⁻⁷ mol Pa⁻¹ m⁻² s⁻¹, respectively). The membrane using the Si-formed α-Al₂O₃ tube was more stable in corrosive HI gas than a membrane with a γ-Al₂O₃-formed α-Al₂O₃ tube after 300 h of stability tests. In conclusion, the developed silica membranes using the Si-formed α-Al₂O₃ tubes seem suitable for membrane reactors that produce H₂ on large scale using HI decomposition in the thermochemical iodine–sulfur process.