A survey on handling computationally expensive multiobjective optimization problems using surrogates: non-nature inspired methods

Computationally expensive multiobjective optimization problems arise, e.g. in many engineering applications, where several conflicting objectives are to be optimized simultaneously while satisfying constraints. In many cases, the lack of explicit mathematical formulas of the objectives and constraints may necessitate conducting computationally expensive and time-consuming experiments and/or simulations. As another challenge, these problems may have either convex or nonconvex or even disconnected Pareto frontier consisting of Pareto optimal solutions. Because of the existence of many such solutions, typically, a decision maker is required to select the most preferred one. In order to deal with the high computational cost, surrogate-based methods are commonly used in the literature. This paper surveys surrogate-based methods proposed in the literature, where the methods are independent of the underlying optimization algorithm and mitigate the computational burden to capture different types of Pareto frontiers. The methods considered are classified, discussed and then compared. These methods are divided into two frameworks: the sequential and the adaptive frameworks. Based on the comparison, we recommend the adaptive framework to tackle the aforementioned challenges.     

硫化锌薄膜的制备和结构分析

用常规分舟热蒸发法在玻璃衬底上制备硫化锌薄膜，用X射线衍射和透射电子显微镜研究该薄膜的晶体结构，发现硫化锌薄膜与流化锌粉末在晶体结构上存在差异，实验证实硫化锌晶体是具有高于性的共价键晶体。     

Trends and international comparisons in infertility in circumpolar areas

A study was carried out at the International Livestock Research Institute (ILRI) Debre Berhan Research Station in Ethiopia from 1992 to 1995 to compare the peri-parturient rise (PPR) in faecal nematode egg counts (FEC) in ewes of two indigenous sheep breeds. A total of 1439 Menz and 1347 Horro ewes were single sire mated following oestrus synchronization to lamb in the wet and dry season. Three ewe treatment groups were constituted as mated/lactating/undrenched; mated/lactating/drenched; unmated/undrenched for three wet and three dry lambing seasons. All ewes grazed naturally contaminated pasture. Levels of faecal egg output were monitored at mating, 3 months after mating, 2 weeks before lambing, 4, 8 and 12 weeks post-lambing. A significant PPR in FEC occurred 2 weeks before lambing and peaked at 4 weeks post-parturition in ewes lambing just before the beginning of the dry season (October/November). There was no significant increase in FEC when lambing occurred before the onset of the long rainy season (May/June). The PPR in this study was associated with both lactation and seasonal availability of third-stage infective larvae on pasture. There was no consistent breed difference in FEC during the six sampling periods from mating to weaning. Faecal cultures and worm counts from both breeds confirmed the presence of Longistrongylus (Pseudomarshallagia) elongata, Trichostrongylus spp.and Haemonchus contortus. The role of the peri-parturient rise of FEC in ewes in gastrointestinal nematode transmission is discussed.     

冻融循环对玻璃纤维布加固混凝土梁受力性能影响

外贴纤维增强塑料 (FRP)对混凝土结构进行补强加固 ,近些年在国内外受到广泛的重视。由于这种材料用在混凝土结构补强加固上时间不长 ,其长期加固性能仍然没有得到证实。尤其是北方较寒冷地区 ,冻融循环是造成结构破坏的主要原因之一 ,因此研究冻融循环对纤维增强塑料加固混凝土结构的影响十分有意义。本文采用快速冻融试验方法 ,研究冻融循环对玻璃纤维布材料、玻璃纤维布与混凝土粘结强度的影响 ,并研究冻融循环对玻璃纤维布加固混凝土梁受力性能的影响。     

Casein‐Based Powders: Characteristics and Rehydration Properties

Casein‐based powders are gaining industrial interest due to their nutritional and functional properties, but they are also known to have poor rehydration abilities. The fundamental physical and chemical mechanisms involved in the rehydration of these powders are essential for determining the critical steps in the manufacturing processes and for developing casein powders with improved rehydration properties. A number of analytical methods have been developed to measure the rehydration ability of powders, but criteria for the selection of methods for casein‐based powders have not been provided. This review article provides an overview of the characteristics and methods for the production of casein‐based powders, methodologies to measure their rehydration properties, and it summarizes the current state of understanding regarding rehydration. Advancements have been made in the field; however, a fundamental understanding enabling improvement of the rehydration properties of these powders is still lacking.     

ELISA法测定花生油中黄曲霉毒素B_1含量的不确定度分析

根据CNAS-GL06:2006《化学分析中不确定度的评估指南》中提供的方法,对ELISA法测定花生油中黄曲霉毒素B1含量过程中影响测定结果的因素进行分析,建立数学模型,对模型中的变量进行分解,确定影响每一变量的不确定度分量并进行计算,合成标准不确定度和扩展不确定度。花生油中黄曲霉毒素B1含量测定结果为(18.3±0.97)μg/kg,通过评定,影响含量测定的最主要不确定度分量为标准曲线的拟合。     

Distinction between arrhythmic and nonarrhythmic death after acute myocardial infarction based on heart rate variability, signal-averaged electrocardiogram, ventricular arrhythmias and left ventricular ejection fraction

OBJECTIVES: We investigated whether heart rate variability, the signal-averaged electrocardiogram (ECG), ventricular arrhythmias and left ventricular ejection fraction predict the mechanism of cardiac death after myocardial infarction. BACKGROUND: Postinfarction risk stratification studies have almost exclusively focused on predicting the risk of arrhythmic death. The factors that identify and distinguish persons at risk for arrhythmic and nonarrhythmic death are poorly known. METHODS: Heart rate variability, the signal-averaged ECG, ventricular arrhythmias and left ventricular ejection fraction were assessed in 575 survivors of acute myocardial infarction. The patients were followed up for 2 years; arrhythmic and nonarrhythmic cardiac deaths were used as clinical end points. During the follow-up period, 47 cardiac deaths occurred, 29 (62%) arrhythmic and 18 (38%) nonarrhythmic. RESULTS: All risk factors were associated with cardiac mortality in univariate analysis. With the exception of left ventricular ejection fraction, they were also predictors of arrhythmic death. Depressed heart rate variability (p < 0.001), ventricular ectopic beats (p < 0.001) and low ejection fraction (p < 0.001) were related to nonarrhythmic death. In multivariate analysis, depressed heart rate variability (p < 0.001) and runs of ventricular tachycardia (p < 0.05) predicted arrhythmic death. Nonarrhythmic death was associated with depressed heart rate variability (p < 0.001), ventricular ectopic beats (p < 0.001) and low ejection fraction (p < 0.01). By selecting patients with depressed heart rate variability, long filtered QRS duration or ventricular arrhythmias and excluding patients with the lowest ejection fraction, we identified a group in which 75% of deaths were arrhythmic. Similarly, by selecting patients with a low ejection fraction and excluding patients with the lowest heart rate variability, we identified a group in which 75% of deaths were nonarrhythmic. CONCLUSIONS: Arrhythmic death was associated predominantly with depressed heart rate variability and ventricular tachycardia runs, and nonarrhythmic death with low ejection fraction, ventricular ectopic beats and depressed heart rate variability. A combination of risk factors identified patient groups in which a majority of deaths were either arrhythmic or nonarrhythmic.