Controlling mechanical systems with backlash—a survey

Backlash is one of the most important non-linearities that limit the performance of speed and position control in industrial, robotics, automotive, automation and other applications. The control of systems with backlash has been the subject of study since the 1940s. This survey reveals that surprisingly few control innovations have been presented since the early path breaking papers that introduced the describing function analysis of systems with backlash. Promising developments are however taking place using adaptive and non-linear control strategies.     

An optimality criteria based method for discrete design optimization taking into account buildability constraints

This paper presents a heuristic design optimization method specifically developed for practicing structural engineers. Practical design optimization problems are often governed by buildability constraints. The majority of optimization methods that have recently been proposed for design optimization under buildability constraints are based on evolutionary computing. While these methods are generally easy to implement, they require a large number of function evaluations (finite element analyses), and they involve algorithmic parameters that require careful tuning. As a consequence, both the computation time and the engineering time are high. The discrete design optimization algorithm presented in this paper is based on the optimality criteria method for continuous optimization. It is faster than an evolutionary algorithm and it is free of tuning parameters. The algorithm is successfully applied to two classical benchmark problems (the design of a ten-bar truss and an eight-story frame) and to a practical truss design optimization problem.     

Amperometric biosensor for formic acid in air

The possibility of developing a simple, inexpensive and specific personal passive “real-time” air sampler incorporating a biosensor for formic acid was investigated. The sensor is based on the enzymatic reaction between formic acid and formate dehydrogenase (FDH) with nicotinamide adenine dinucleotide (NAD⁺) as a co-factor and Meldola's blue as mediator. An effective way to immobilise the enzyme, co-factor and Meldola's blue on screen-printed, disposable, electrodes was found to be in a mixture of glycerol and phosphate buffer covered with a gas-permeable membrane. Steady-state current was reached after 4–15 min and the limit of detection was calculated to be below 1 mg/m³. However, the response decreased by 50% after storage at −15°C for 1 day.     

板坯和方坯连铸机的高速切割和去毛刺机械

如果现代化的连铸机不装备高效切割和去毛刺装置,连铸机的效率就会受影响.除常规火焰切割机SOBS以外,GeGe公司成功开发了高压氧气切割装置HOBS.     

Pheromones and Other Semiochemicals for Monitoring Rare and Endangered Species

As global biodiversity declines, biodiversity and conservation have become ever more important research topics. Research in chemical ecology for conservation purposes has not adapted to address this need. During the last 10–15 years, only a few insect pheromones have been developed for biodiversity and conservation studies, including the identification and application of pheromones specifically for population monitoring. These investigations, supplemented with our knowledge from decades of studying pest insects, demonstrate that monitoring with pheromones and other semiochemicals can be applied widely for conservation of rare and threatened insects. Here, I summarize ongoing conservation research, and outline potential applications of chemical ecology and pheromone-based monitoring to studies of insect biodiversity and conservation research. Such applications include monitoring of insect population dynamics and distribution changes, including delineation of current ranges, the tracking of range expansions and contractions, and determination of their underlying causes. Sensitive and selective monitoring systems can further elucidate the importance of insect dispersal and landscape movements for conservation. Pheromone-based monitoring of indicator species will also be useful in identifying biodiversity hotspots, and in characterizing general changes in biodiversity in response to landscape, climatic, or other environmental changes.     

Perceived urban design qualities and affective experiences of walking

This study investigates associations between perceived micro-level urban design qualities, the affective experience of walking, and intention to walk specific routes in the neighbourhood. A total of 106 residents assessed on-site three routes planned for walking in semi-central neighbourhoods. In the prediction of the residents’ intention to choose to walk and intention to avoid walking the route, perceived urban design qualities were mediated by the affective experience of valence of the walk. The perceived complexity and aesthetic quality, upkeep and order, and the presence of well-maintained greenery, were identified as important. These perceived urban design qualities and affective experiences varied between the three routes, but also within the routes. It is proposed that understanding of site-specific affective experience of walking environments could serve as guidance for urban design practices.     

User perceptions of ICT impacts in Swedish construction companies: ‘it’s fine,just as it is’

The use of information and communication technologies (ICT) in construction companies has been growing steadily during the last decade. However, few studies inquire into either perceptions of the impact of actual ICT use or perceptions among different occupational groups in construction companies. The aim of the paper is to explore users’ general perceptions of ICT impacts in the post-adoption stage and analyse the implications for construction management practice. A mixed methods approach was used. Quantitative data were collected using a web-based survey both in a major construction company and among medium-sized companies in Sweden. Data from 294 returned completed questionnaires were analysed with t-tests and multiple regression analysis. In addition, participant observations and semi-structured interviews were conducted within the major construction company in order to strengthen the analysis. It can be concluded that respondents are generally fairly satisfied with the ICT. Differences in perceptions among occupational groups can be explained by the nature of work tasks and the original intentions for using ICT as a means of control and calculation. Even if respondents perceive that a further development of ICT could improve competitiveness, they do not want to increase their use of it in their workplaces. They basically think that ‘it is fine, just as it is’. This indicates that a challenge in construction management is to investigate how prevailing and new ICT applications can be used to develop the industry.     

Interobjectivity in architectural research and theory: towards a meta-theory of materiality and the effects of architecture and everyday life

The aim of this article is to introduce a meta-theoretical discussion in architectural research about materiality and its effect on everyday life and use. Taking a relational perspective, I distinguish between three different perspectives on materialities as described in theories in recent decades. From these perspectives I develop three possible conceptualisations of interobjectivity. The first perspective sees interobjectivity as collaboratively constructed ‘cross-road effects’. The second perspective sees interobjectivity as the process of stitching together material heterogeneities. The third perspective sees interobjectivity as the radiance of a persistent identity through different contexts. These three perspectives each contribute to the ways architectural objects and spaces interact and produce effects. These effects are often discussed within separate paradigms. Putting them together as different modalisations of interobjectivity enables a much richer empirical analysis, where the notion of ‘material effects’ can be differentiated and compared.