主成分分析法评价树莓中挥发性香气成分气味活度值

目的 以气味活度值为依据,采用主成分分析法评价树莓中典型性挥发性香气成分.方法 应用顶空固相微萃取技术与气相色谱-质谱联用技术分离鉴定不同树莓的挥发性香气成分,结合气味阈值评价16个不同品种树莓的气味活度值,并采用气味轮图法确定树莓的香气类型,运用主成分分析评价树莓中不同香气成分对整体香气的贡献.结果 Mac blac...     

基于向量空间的多子网复合复杂网络模型动态组网运算的形式描述

针对典型复杂网络模型仅描述了复杂系统中同一类个体及其间一种相互关系且对问题的讨论仅局限于同一个系统的问题,基于能够描述复杂系统中异类个体间多种关系的多子网复合复杂网络模型,导入多维向量空间,将网络节点间的关系映射为多维向量,定义了向量复合网.在此基础上,将该模型的动态组网运算(加载与退缩)转化为向量空间的基变换,给出了加载运算与退缩运算的形式描述,实现了多子网复合复杂网络的可计算.建立并分析了我国铁路客运复合网,通过网络动态重组运算,基于高速铁路子网与低速铁路子网的拓扑性质,给出了我国铁路发展现状分析.     

数字分形图像分形维数计算

针对数字图像分形维数计算准确度较低问题,为提高图像精确性,消除噪声,设计了基于图像处理和分形维数计算的一体化系统.对具有分形特征的数字图像进行了灰度转换、去噪、阈值分割和轮廓提取处理,得到二值轮廓数字图像;利用计盒维数算法,统计一系列不同像素边长的正方形覆盖二值轮廓数字图像,根据像素数量和正方形个数之间的关系,确定数字图像的分形维数.结果表明,对分形图像的处理简单、方便,通过对kochsnow曲线、Sierpinski垫片等有规则分形图像分形维数的仿真计算,验证了方法的准确性、可靠性和简便性,能为数字图像分形维数的计算提供可靠工具.     

Temporal pattern attention for multivariate time series forecasting

Forecasting of multivariate time series data, for instance the prediction of electricity consumption, solar power production, and polyphonic piano pieces, has numerous valuable applications. However, complex and non-linear interdependencies between time steps and series complicate this task. To obtain accurate prediction, it is crucial to model long-term dependency in time series data, which can be achieved by recurrent neural networks (RNNs) with an attention mechanism. The typical attention mechanism reviews the information at each previous time step and selects relevant information to help generate the outputs; however, it fails to capture temporal patterns across multiple time steps. In this paper, we propose using a set of filters to extract time-invariant temporal patterns, similar to transforming time series data into its “frequency domain”. Then we propose a novel attention mechanism to select relevant time series, and use its frequency domain information for multivariate forecasting. We apply the proposed model on several real-world tasks and achieve state-of-the-art performance in almost all of cases. Our source code is available at https://github.com/gantheory/TPA-LSTM.

     

Effect of spraying on chemical properties and bactericidal efficacy of electrolysed oxidizing water

A three‐factor, three‐by‐three‐by‐two‐level factorial designs were used for studying the effects of air pressure, sprayer orifice size and electrostatic charge of a spray gun on pH, oxidation‐reduction potential (ORP), electric conductivity and residual chlorine of electrolysed oxidizing (EO) waters with either low (9 mg L^?1) or high concentration (88 mg L^?1) of chlorine. Results indicated that a smaller orifice produced higher reduction in ORP and chlorine concentration than larger orifices. Electrostatic charge, in general, did not cause a significant reduction in chlorine concentration. High air pressure spray retained more chlorine and gave a higher ORP than low air pressure. EO water with high initial chlorine concentration achieved at least a 3–4 log₁₀ CFU mL^?1 reduction in Listeria monocytogenes populations when sprayed with the spray gun, while spraying with a commercial backpack sprayer or a poly‐tank sprayer eliminated Listeria population (9.4 log₁₀ CFU mL^?1 reductions) completely. These results demonstrated that although spraying reduced the chlorine in EO water by 20–97%, application of EO water through spraying has potential for reducing bacteria in food‐processing operations.