The sociotechnical constitution of cognitive work analysis: roles,affordances and malfunctions

Analysis of everyday work practices in sociotechnical systems for eliciting design/intervention requirements involves appropriate work analysis frameworks. The current article provides an extension to one such framework — Cognitive Work Analysis (CWA) — by scrutinising its sociotechnical basis. CWA's forte depends on its ‘design for adaptation’, system related operations, and operators. In contrast, sociotechnical work systems require not only operators and adaptation, but also a significant emphasis on ‘users’ and ‘appropriation’. The current article extends CWA (based on Rasmussen's original concepts) for users; subsequently allowing for system flexibility and possibilities of ‘appropriation’ within acceptable boundaries of the system's correct functioning. To this end, the first phase of Work Domain Analysis is extended by adding a new layer to the abstraction hierarchy (AH), based on Rasmussen's original insights.     

利用钛白废酸从粉煤灰中提取铝的研究

介绍了用工业钛白废酸提取粉煤灰中铝的新技术 ,试验研究了浸出过程中各因素对浸出率的影响 ,提出了最佳浸出工艺条件 .这为用钛白废酸提取粉煤灰中铝提供了新的方法 ,并为综合利用钛白废酸和粉煤灰又开辟了一个新的途径 .利用钛白废酸从粉煤灰中提取铝将具有较大的环境、经济和社会效益 .     

A versatile strategy towards semi-interpenetrating polymer network for proton exchange membranes

A universal method to prepare proton exchange membrane (PEM) with semi-interpenetrating polymer network (semi-IPN) via a versatile crosslinker 1,3-benzenedisulfonyl azide (1,3-BDSA) is proposed. Sulfonyl azide groups can react with any polymer with carbon-hydrogen bonds via hydrogen abstraction. Polyvinylidene fluoride (PVDF) and perfluorosulfonic acid (PFSA) polymer are selected as two precursors for semi-IPN. When 1,3-BDSA is heated to a sufficiently high temperature it can form the nitrene and connect with PVDF via hydrogen abstraction reaction, recombination, or CH-bond insertion. The crosslinking structure of PVDF is formed, and semi-IPN is constructed in the presence of PFSA at the same time. The mechanical properties, degree of crosslinking, water uptake, and proton conductivity of semi-IPN membranes are investigated. Compared with pure PFSA membrane, the mechanical properties and the dimensional stability of the semi-IPN membranes are improved significantly. The tensile strength of the composite membrane (27.2 MPa) is much higher than that of PFSA membrane (10.1 MPa). The maximum power density of the composite membrane can reach 382 mW cm⁻² at 940 mA cm⁻². Sulfonyl azide based crosslinkers can be used to prepare semi-IPN or IPN PEMs from any paired polymers with carbon–hydrogen bonds.     

A novel video abstraction method based on fast clustering of the regions of interest in key frames

Online video nowadays has become one of the top activities for users and has become easy to access. In the meantime, how to manage such huge amount of video data and retrieve them efficiently has become a big issue. In this article, we propose a novel method for video abstraction based on fast clustering of the regions of interest (ROIs). Firstly, the key-frames in each shot are extracted using the average histogram algorithm. Secondly, the saliency and edge maps are generated from each key-frame. According to these two maps, the key points for the visual attention model can be determined. Meanwhile, in order to expand the regions surrounding the key points, several thresholds are calculated from the corresponding key-frame. Thirdly, based on the key points and thresholds, several regions of interest are expanded and thus the main content in each frame is obtained. Finally, the fast clustering method is performed on the key frames by utilizing their ROIs. The performance and effectiveness of the proposed video abstraction algorithm is demonstrated by several experimental results.     

Visual abstraction of dynamic network via improved multi-class blue noise sampling

Massive sequence view (MSV) is a classic timeline-based dynamic network visualization approach. However, it is vulnerable to visual clutter caused by overlapping edges, thereby leading to unexpected misunderstanding of time-varying trends of network communications. This study presents a new edge sampling algorithm called edge-based multi-class blue noise (E-MCBN) to reduce visual clutter in MSV. Our main idea is inspired by the multi-class blue noise (MCBN) sampling algorithm, commonly used in multi-class scatterplot decluttering. First, we take a node pair as an edge class, which can be regarded as an analogy to classes in multi-class scatterplots. Second, we propose two indicators, namely, class overlap and inter-class conflict degrees, to measure the overlapping degree and mutual exclusion, respectively, between edge classes. These indicators help construct the foundation of migrating the MCBN sampling from multi-class scatterplots to dynamic network samplings. Finally, we propose three strategies to accelerate MCBN sampling and a partitioning strategy to preserve local high-density edges in the MSV. The result shows that our approach can effectively reduce visual clutters and improve the readability of MSV. Moreover, our approach can also overcome the disadvantages of the MCBN sampling (i.e., long-running and failure to preserve local high-density communication areas in MSV). This study is the first that introduces MCBN sampling into a dynamic network sampling.     

Interpolymer radical coupling: A toolbox complementary to controlled radical polymerization

The current review focuses on the relevance and practical benefit of interpolymer radical coupling methods. The latter are developing rapidly and constitute a perfectly complementary macromolecular engineering toolbox to the controlled radical polymerization techniques (CRP). Indeed, all structures formed by CRP are likely to be prone to radical coupling reactions, which multiply the available synthetic possibilities. Basically, the coupling systems can be divided in two main categories. The first one, including the atom transfer radical coupling (ATRC), silane radical atom abstraction (SRAA) and cobalt-mediated radical coupling (CMRC), relies on the recombination of macroradicals produced from a dormant species. The second one, including atom transfer nitroxide radical coupling (ATNRC), single electron transfer nitroxide radical coupling (SETNRC), enhanced spin capturing polymerization (ESCP) and nitrone/nitroso mediated radical coupling (NMRC), makes use of a radical scavenger in order to promote the conjugation of the polymer chains. More than a compilation of macromolecular engineering achievements, the present review additionally aims to emphasize the particularities, synthetic potential and present limitations of each system.     

建构与生成——战后日本现代建筑的演变

试图结合日本战后社会、经济、文化等各方面发展的不同阶段,把日本现代建筑的发展历程划分为五个不同的时期,通过分析各个时期具有代表性的建筑师及其作品,梳理出日本在吸收、消化西方现代建筑理念的基础上,融合本国传统的木结构建筑文化,逐步建构、生成了具有独特风格的日本现代建筑的脉络。     

基于抽象解释的变量值范围分析及应用

精确的变量值范围分析对于编译器优化、静态分析和软件测试至关重要.在介绍抽象解释理论的基础上,扩展了经典的区间抽象,首次提出区间集的概念并定义了新的数值型区间集代数、布尔型和引用型区间代数,给出了统一的基于抽象解释的变量值范围分析方法RABAI,引入拓宽算子计算循环体变量范围,对过程参数定义了特殊的未定义取值(undef...     

齿轮泵压力信号的负熵基ICA特征提取和故障诊断

齿轮泵动态压力信号蕴含了丰富的状态信息,是齿轮泵的关键性能参数之一;负熵是随机变量独立性的自然测度,反映了机械信号信息的动态变化特征。为了进行基于齿轮泵动态压力信号的故障诊断,在引入经验模态分解技术的基础上,提出了齿轮泵压力信号的负熵基ICA特征提取方法,并进而联合最小二乘支持向量机,探讨了基于ICA和LS-SVM的齿轮泵特征提取和故障诊断方法;理论和试验研究表明,基于负熵的ICA特征提取和故障诊断方法是有效的。     

混乱之美与复数场所的集结

本文主要分析了筱原一男于1976年设计的“上原的住宅”。筱原自己将其一系列住宅作品按照样式进行了排序。在对样式变迁进行整理的基础上，本文对“第3样式”的初期作品“上原的住宅”中筱原的思想从实际形态和架构进行考察，并通过“裸形的事物”、“错位”等关键词将这一作品定位为从抽象空间向具体空间的转变。与这一转变并行的是，从“传统”到“都市”的文脉转变。“上原的住宅”具有混乱的美与复数场所的集结，以此作为本文结论。