Nina Heidenstrøm  Linda Kvarnlöf 《突发事故与危机管理杂志》2018,26(2):272-282

The article focuses on how rural households cope with blackouts caused by winter storms. We approach household preparedness using a practice theory perspective, and argue that preparedness is mundanely preformed as part of everyday practices. The data material consists of at home visits to 14 households from Norway and Sweden. The results demonstrate that households cope with blackouts by activating and mobilising competences, meanings and materials belonging to different practices, and that this is an ongoing process to ensure the continuation of everyday life during disruption. The article concludes by arguing for the need to bring forward studies on informal preparedness activities, in a research field where household preparedness tends to be framed using a top‐down perspective on crisis management.  相似文献   

    

Boström  Magnus 《Cognition, Technology & Work》2018,20(3):443-456

Cognition, Technology & Work - Icebreakers are special-purpose ships designed to operate in different ice-covered waters, either independently or during assistance of weaker ships. In the...  相似文献   

    

Siavash H. Khajavi  Gege Deng  Jan Holmström  Pasi Puukko  Jouni Partanen 《国际生产研究杂志》2018,56(14):4874-4896

The paper analyses the impact of cheaper metal powder supplies on the comparative competitiveness of additive manufacturing (AM). By utilising two case studies, we compare the economic impact of an innovative titanium extraction method on Selective Laser Melting (SLM) and conventional methods of machining and casting. A switch-over analysis identifies the production quantities above which conventional manufacturing is more cost competitive than additive manufacturing. This analysis is performed for current raw material as well as cheaper raw material supply. The results illustrate the improved comparative competitiveness of SLM as the titanium supply is commoditised and more readily available in powder form. The responsiveness of the supply chain is improved as the switch-over point between SLM and conventional methods increases. Moreover, as the raw material supply chain for titanium is transformed through the use of this novel extraction method, the manufacturing supply chain is simplified.  相似文献   

    

Åsa Nyflött  Yana Petkova‐Olsson  Ellen Moons  Chris Bonnerup  Lars Järnström  Gunilla Carlsson  Magnus Lestelius  Matteo Minelli 《应用聚合物科学杂志》2017,134(20)

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Sennur Alay Aksoy  Cemil Alkan  M. Selda Tözüm  Sena Demirbağ  Ruhan Altun Anayurt  Yusuf Ulcay 《纺织学会志》2017,108(1):30-41

In this study, a series of microencapsulated phase change materials with poly(methyl methacrylate-co-methacrylic acid) P(MMA-co-MAA) shell and n-octadecane or n-eicosane core were synthesized by emulsion polymerization method. The aim was to produce microencapsulated n-alkanes having functional groups on their outer surface, so that functional groups would help increasing physical interactions between microcapsules and fiber surface. Therefore, methyl methacrylate (MMA), ethylene glycoldimethacrylate (EGDM), and methacrylic acid (MAA) were copolymerized in oil phase of n-alkane. FT-IR results proved the successful synthesis of P(MMA-co-MAA) shell of microencapsulated n-alkanes. The DSC results indicated that the microencapsulated n-alkanes have considerable latent heat storage capacity in a range of 58–145 J/g. The average melting and freezing temperatures of the microencapsulated n-alkanes were measured as 27 and 26 °C for n-octadecane and 36 and 35 °C for n-eicosane, respectively. The microcapsules were of spherical and compact shape with particle sizes between 15 and 32 μm. The microcapsules on the cotton fabric applied by pad-dry-cure method were found highly durable and they showed sufficient stability upon several washings and rub fastness. Thermo-regulating properties of the fabrics were declared as a result of thermal history measurements.  相似文献   

    

Kashif Ghafoor  Mehmet Musa Özcan  Fahad AL‐Juhaımı  Elfadıl E. Babıker  Zaidul Islam Sarker  Isam A. Mohamed Ahmed  Mohammed Asif Ahmed 《European Journal of Lipid Science and Technology》2017,119(7)

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Ferah Çoğun  Ender Yıldırım  M. A. Sahir Arikan 《Materials and Manufacturing Processes》2017,32(16):1838-1844

In this study, effects of embossing temperature, time, and force on production of a microfluidic device were investigated. Polymethyl methacrylate (PMMA) substrates were hot embossed by using a micromilled aluminum mold. The process parameters were altered to observe the variation of replication rate in width and depth as well as symmetry of the replicated microfluidic channels. Analysis of variance (ANOVA) on the experimental results indicated that embossing temperature was the most important process parameter, whereas embossing time and force have less impact. One distinguishing aspect of this study is that, the channels were observed to be skewed to either side of the channel depending on the location of the protrusions on the mold. The mechanism of the skewness was investigated by finite element analysis and discussed in detail. Results showed that the skewness depends on the flow characteristics of the material and could be reduced by increasing the embossing temperature. The best replication rates were obtained at parameter settings of 115°C, 10?kN, and 8?min for the molds with minimum 56?µm wide features of 120?µm depth. We also showed that the fabricated channels could be successfully sealed by solvent-assisted thermo-compressive bonding at 85°C under 5.5?kN force.  相似文献   

    

Blaise L. Tardy  Mariko Ago  Jiaqi Guo  Maryam Borghei  Tero Kämäräinen  Orlando J. Rojas 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(47)

Hierarchically structured materials comprising rod‐like, chiral, nanoparticles are commonly encountered in nature as they can form assemblies with exceptional optical and mechanical characteristics. These include cellulose nanocrystals (CNCs), which have a large potential for the fabrication of bioinspired materials mimicking those advanced properties. Fine‐tuning the optomechanical properties of assemblies obtained from CNCs hinges on the transformations from suspensions of liquid crystals to long‐range order in the dry state. So far, associated transitions have been studied using trivial interfaces such as planar substrates. Such transitions are explored as they evolve onto meshed supports. The meshed substrate offers a complex topology, as is encountered in nature, for the formation of CNCs films. The CNCs self‐assembly occurs under confinement and support of the framework bounding the mesh openings. This leads to coexisting suspended and supported nanoparticle layers exhibiting nematic and/or chiral nematic order. Optical microscopy combined with crossed polarizers indicate that the formation of the suspended films occurs via intermediate gelation or kinetic arrest of CNCs across the mesh's open areas. The formation of self‐standing, ultrathin films of CNCs with tunable optical properties, such as selective reflections in the visible range (structural color), is demonstrated by using the presented simple and scalable approach.  相似文献   

    

E. Alper Yıldırım 《Optimization methods & software》2017,32(6):1163-1186

Every quadratic programming problem with a mix of continuous and binary variables can be equivalently reformulated as a completely positive optimization problem, that is, a linear optimization problem over the convex but computationally intractable cone of completely positive matrices. In this paper, we focus on general inner approximations of the cone of completely positive matrices on instances of completely positive optimization problems that arise from the reformulation of mixed binary quadratic programming problems. We provide a characterization of the feasibility of such an inner approximation as well as the optimal value of a feasible inner approximation. In particular, our results imply that polyhedral inner approximations are equivalent to a finite discretization of the feasible region of the original completely positive optimization problem. Our characterization yields, as a byproduct, an upper bound on the gap between the optimal value of an inner approximation and that of the original instance. We discuss the implications of this error bound for standard and box-constrained quadratic programs as well as general mixed binary quadratic programs with a bounded feasible region.  相似文献   

    

Elsa Kristiansen  Fredrik Hland Johansen  Eric Carlstrm 《突发事故与危机管理杂志》2019,27(1):72-78

Inter‐organizational collaboration is increasingly a topic for studies into accidents and disasters as well as exercises. In this study, which is based on interviews with first responders, we compared perceived collaboration during an exercise with crisis work. The three organizations included in this study—fire department, police and ambulance services—perceived the investigated tunnel exercise completely different, ranging from harmonious interaction to power struggles between commanding officers, fragmented decision‐making and ambiguity. When comparing the exercise with an incident, we found that collaboration was more evident during incidents than in exercises. However, collaboration exercises appear to improve inter‐organizational collaboration by stimulating informal structures, practicing listening and delegating, getting to know one another and learning a common language.  相似文献