矩阵变换器在不平衡输入电压下的控制策略

通过检测矩阵变换器的瞬时输入电压并实时调节输出电压调制矢量,采用空间矢量调制策略的矩阵变换器能够在不平衡且非正弦的输入电压下得到正弦平衡的输出电压。在非平衡输入电压下,若输入功率因数角不变,矩阵变换器的输入电流将不再正弦。本文给出了输入电流与输出功率及输入功率因数角之间的关系,通过调节输入电流调制矢量的方向,可得到正弦但不平衡的输入电流。仿真证明了理论的正确性。     

Pitch-based carbon foam electrodeposited with lead as positive current collectors for lead acid batteries

Lead electrodeposited carbon foam (LCF), whose substrate was made from pitch by a template method, was investigated as possible positive current collectors for lead acid batteries. Scanning electron microscopy, cyclic voltammetry, and galvanostatic charge–discharge tests were employed to characterize the effect of the proposed collector on the structure and electrochemical properties of the positive active material (PAM). The LCF with uniform and dense lead coating shows the similar electrochemical characteristics to metallic lead in the voltage range where the positive electrodes of lead acid batteries operate. The LCF and lead slices were used as the positive current collectors to equip lead acid batteries, respectively. Comparative charge–discharge tests show that a battery equipped with a LCF collector exhibits higher PAM utilization efficiency and longer cycle life, for LCF can provide large specific surface area which is beneficial to electrochemical reactions and PAM adhesion. In addition, a light lead acid battery with a LCF positive current collector and a carbon foam negative current collector was made and tested for the first time. It deserves systematic industrial study in the future.     

压缩机启动器保护器备用保护系统(IBPS)的市场趋势研究

本文针对冰箱、空调及其压缩机存在的安全保护问题,介绍了压缩机PTC启动器和过载保护器(业内简称两器)的备用保护系统(IBPS)的概念与由来,就市场中现有的IBPS阐述工作原理,分析了亚洲各国的市场需求,并对未来几年IBPS在市场上的需求量作了分析和预测。随着家电企业对安全要求的进一步提高,在日本、韩国企业广泛接受的背景下,IBPS会越来越多地被中国及全球各国家电行业采用。     

中国与日本兽药残留限量标准比较分析研究

目的研究我国与日本兽药残留限量标准的异同。方法根据中华人民共和国国农业部第235号公告以及日本肯定列表、厚生劳动省第370号公告,比较两国法律法规涉及的禁用与限量物质清单在兽药种类、残留食品种类、残留限量指标值等方面的异同。结果我国兽药残留限量标准涉及123种兽药、3大类食品、12种动物与9种靶组织、550个限量指标,日本则涉及243种兽药、4大类食品、16种动物与8种靶组织、3705个限量指标。两者相比,我国83种兽药与日本相同, 445个限量指标与日本810个限量指标具有可比性。在中日标准涉及的具有可比性的限量指标中,我国有215个指标与日本等同,有80个指标比日本严格,有139个指标比日本宽松。结论在兽药残留限量标准涉及的可比指标值方面,我国二分之一的指标值与日本对应指标值是等同的。     

Quasi gradient-based inversion-free iterative algorithm for solving a class of the nonlinear matrix equations

Inspired by the gradient-based and inversion-free iterations, a new quasi gradient-based inversion-free iterative algorithm is proposed for solving the nonlinear matrix equation $X+A^{\mathrm{T}}{X}^{?n}A=I$. The convergence proof of the suggested algorithm is given. Several matrix norm inequalities are established to depict the convergence properties of this algorithm. Three numerical examples are given to illustrate the effectiveness of the suggested algorithms.     

From enfant terrible to problem-solver? Tracing the competing discourse to explain blockchain-related technological diffusion

Since the inception of blockchain-related technologies over a decade ago, investors’ uptake of the technologies has grown rapidly. But even with the advancement in standing from conceptual beginnings to real-world experimentation, mainstream adoption of the technologies in either organizational or individual contexts has yet to eventuate. To resolve this paradox, we examine progression of the technologies’ diffusion instead, and in the process, seek to uncover the underlying dynamics of sentiments at play. Diffusion involves multiple actions by different parties, with social discourses via diverse media playing an essential role. In demonstrating the interplay of support to resistance via media framing and the diffusion of innovation theory, findings from our paper contribute to the technology adoption literature. Understanding resistant behavior toward a new technology area could help resolve potential issues that may arise. This would hopefully lead to better technological implementation outcomes in future.     

Contextual acceptance of insect-based foods

Insect-based foods have gained much attention as an alternative source of protein in recent years because of their high nutritional content and low production costs. However, consumer acceptance of insect-based foods still poses a big challenge in many societies. Across three studies, we examined how social companions (alone, friend, family, acquaintance, partner) and location (cafe, bar, pub, food festival) are associated with people’s willingness to eat insect-based foods. We also examined the positive arousing (fun, excitement) and positive calming (romance, tranquility) emotions that were evoked by several eating contexts. The results of Studies 1 and 2 revealed that participants expected that they would be more willing to eat insect-based foods with friends (vs. alone, family, acquaintance, partner) and in pubs and at food festivals (vs. in a cafe, bar). The results of Study 3 replicated the main findings of the first two studies using the actual names (not pictures) of insect-based food products, namely ‘mealworm burger’ and ‘cricket chocolate bar’. Moreover, these contexts, where people would be more willing to eat insect-based foods, were associated with positive arousing emotions (fun, excitement) rather than positive calming emotions (romance, tranquility). Taken together, then, these findings reveal the role of contexts associated with positive arousing emotions in eating insect-based foods and provide practical advice concerning the situations in which the consumer’s acceptance of insect-based foods may be increased.     

基于PU学习的链接预测方法

基于分类的链接预测方法中,由于链接未知节点对的大规模性与不确定性,选择可靠负例成为构造链接预测分类器的难点问题.为此,文中提出基于正例和无标识样本(PU)学习的链接预测方法.首先,提取节点对的拓扑信息以构造样本集.再利用社区结构确定候选负例的分布,基于分布进行多次欠采样,获得多个候选负例子集,集成多个负例集与正例集中构建的分类器选择可靠负例.最后基于正例与可靠负例构造链接预测分类器.在4个网络数据集上的实验表明文中方法预测结果较优.     

Emotional design and positive emotions in multimedia learning: An eyetracking study on the use of anthropomorphisms

The present eyetracking study examined the influence of emotions on learning with multimedia. Based on a 2 × 2 experimental design, participants received experimentally induced emotions (positive vs. neutral) and then learned with a multimedia instructional material, which was varied in its design (with vs. without anthropomorphisms) to induce positive emotions and facilitate learning. Learners who were in a positive emotional state before learning had better learning outcomes in comprehension and transfer tests and showed longer fixation durations on the text information of the learning environment. Although anthropomorphisms in the learning environment did not induce positive emotions, the eyetracking data revealed that learners' attention was captured by this design element. Hence, learners in a positive emotional state who learned with the learning environment that included anthropomorphisms showed the highest learning outcome and longest fixation on the relevant information of the multimedia instruction. Results indicate an attention arousing effect of expressive anthropomorphisms and the relevance of emotional states before learning.     

正传动非零变位弧齿锥齿轮的设计

根据弧齿锥齿轮的非零变位原理，采用正传动可大幅度提高弧齿锥齿轮的强度和综合性能。本文通过一实例，参照封闭图选择变位系数，对零变位和非零正变位两种设计方案进行了比较，说明正传动非零变位弧齿锥齿轮在综合性能方面具有明显的优越性。