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排序方式： 共有2798条查询结果，搜索用时 15 毫秒
991.
Karoline Aasmul-Olsen Halise Gül Akıllıoğlu Line Iadsatian Christiansen Kasper Engholm-Keller Anders Brunse Denitsa Vladimirova Stefanova Ann Bjørnshave Mie Rostved Bechshøft Kerstin Skovgaard Thomas Thymann Per Torp Sangild Marianne Nissen Lund Stine Brandt Bering 《Molecular nutrition & food research》2024,68(6):2300458
992.
Daniel Vestergaard Peter Noe Poulsen Linh Cao Hoang Kasper Paaske Larsen Bent Feddersen 《Structural Concrete》2023,24(2):2606-2622
The iterative nature of the design processes for building structures requires computational models to be robust, efficient, and accessible while reflecting the actual structural behavior with sufficient accuracy. For limit state analysis of reinforced concrete structures, efficient linear-elastic models are generally inaccurate, while the modeling and computational complexity of most high-accuracy nonlinear models inhibit their use in design processes for large-scale structures. A recently proposed framework for elasto-plastic analysis of cracked reinforced concrete panels was demonstrated to be capable of analyzing models with more than 10,000 finite elements within minutes on a standard personal computer. This paper proposes an extension of this work in terms of a finite shell element for elasto-plastic analysis of fully cracked reinforced concrete wall structures subjected to monotonic loading. Using nonlinear-elastic constitutive models to imitate elasto-plasticity, the proposed shell element couples the in-plane section force variation to the nonlinear through-thickness stress variation in a stress-based formulation using a layer-based submodel. The method is validated with exact solutions, and its applicability in design processes involving large-scale structures is demonstrated using a finite element model of a four-story stairwell with more than three million variables, which is solved within minutes on a personal computer. 相似文献
993.
Daniel Vestergaard Peter Noe Poulsen Linh Cao Hoang Kasper Paaske Larsen Bent Feddersen 《Structural Concrete》2023,24(4):5167-5183
The structural response of slender reinforced concrete (RC) structures may be highly nonlinear due to cracking, reinforcement yielding, and geometrically nonlinear effects. While advanced models can simulate the detailed response of such structures, they are generally ill-suited for limit state verification in practical design scenarios due to a high computational and modeling effort. A design-oriented method for evaluating the geometrically linear response of cracked RC wall structures was recently presented and demonstrated to allow the analysis of large-scale models with more than 2400 finite shell elements within minutes on a standard personal computer. This paper proposes a design-oriented numerical method for efficient instability analysis of slender RC wall structures, also enabling the inclusion of thermal effects. Based on a two-step linearized buckling analysis, the method first determines the geometrically linear structural response by solving the complementary energy minimization problem, including, if relevant, thermal strains and reduced material stiffness. This solution is used to derive the sectional stiffness upon which a linearized buckling problem is formulated and subsequently solved as a linear eigenvalue problem. The model is validated using examples with exact solutions, and its applicability to large-scale models is demonstrated through an example with a four-story stairwell modeled using more than 3200 finite elements. 相似文献
994.
Virtual Reality - Transfer functions with a high translational gain can increase the range of walking in virtual reality. These functions determine how much virtual movements are amplified compared... 相似文献
995.
Gabrielle Susan Zanella Daniela Becker Andrea Lima dos Santos Schneider Ana Paula Testa Pezzin Denise Abatti Kasper Silva André Lourenço Nogueira 《应用聚合物科学杂志》2019,136(39):47998
Silver nanoparticles (AgNp) were synthesized in aqueous phase and transferred to chloroform using a fatty amine as phase transfer agent. Poly(l -lactic acid) (PLLA) membranes were prepared using the “functionalized” chloroform. The amount of AgNp in the chloroform was determined by atomic absorption spectroscopy. Thermogravimetric analysis, differential scanning calorimetry, and field emission scanning electron microscopy were used to characterize the membranes. A decrease of the thermal stability of the membranes was observed upon the addition of AgNp; meanwhile, the polymer crystallinity degree increased, making the membranes more fragile and brittle. The in vitro degradation assessments of the membranes in artificial saliva suggested that the time necessary to degrade the PLLA reduced by raising the concentration of the nanostructures. Additionally, the antibacterial assays demonstrated that the addition of only 13 ppm of AgNp were enough to inhibit the formation of biofilm over the bionanocomposite membranes. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47998. 相似文献
996.
Bjorn de Koeijer Carsten Gelhard Roland ten Klooster 《Packaging Technology and Science》2019,32(12):618-629
Sustainability is well‐established in many companies' strategic postures. However, executing sustainability‐related goals often lags at the operational level. This study analyses how decision‐making processes in packaging development at different hierarchical levels are characterized in achieving a sustainability consensus. This research focuses on the alignment of the strategic and operational levels of packaging development in relation to the integration of sustainability considerations. This materializes in a stakeholder perspective on packaging development and an analysis of targets aiming for the integration of sustainability considerations in such development processes. The involvement and decision making by internal stakeholders, the involvement of external stakeholders and sustainability target setting are considered as conditions causing the outcome of interest: levels of sustainability implementation on both the strategic and the operational levels of packaging development. By using a set‐theoretic method, we address that different compositions of stakeholder involvement and target setting might cause the same level of sustainability priority at the strategic and operational levels. For data analysis, we use a fuzzy‐set qualitative comparative analysis (fsQCA) with empirical data derived from survey responses by packaging experts. This approach is motivated by its ability to address the complexity of the interplay of case characteristics within development processes. The research findings provide several indications of a limited alignment of a company's strategic sustainability ambition with the operational activities of multidisciplinary packaging development teams. The insights on the sustainability‐related configurations of stakeholders and target setting provide guidance for managing projects across the strategic and operational levels in improving sustainable packaging development. 相似文献
997.
Christoph Mittendorf Nicholas Berente Roland Holten 《Information Systems Journal》2019,29(5):1083-1119
The sharing economy is a defining feature of the millennial generation. We report on a study of 1047 millennials and find that trust has more of an impact on their willingness to engage in some sharing encounters than in others. In particular, trust matters more in high‐dimensionality sharing encounters—those encounters that have a longer duration, require a greater financial investment, involve more social interaction, etc. Further, it is important to note that all sharing encounters take place through two‐sided intermediary platforms, and we find that the role of trust among the different types of sharing partners is not symmetrical across the two sides. Trust in the intermediary platform matters more to customers than to service providers in their willingness to engage in service encounters. Overall, this research contributes to existing literature by developing the notion of a service encounter and associated dimensionality and by demonstrating that service encounter dimensionality affects the importance of trust in the sharing economy. Also, we show how trust matters differently for different sides of two‐sided sharing platforms. Finally, this research focuses squarely on understanding the behaviours of millennials—the generation important to the sharing economy. 相似文献
998.
Mathias Bürki Cesar Cadena Igor Gilitschenski Roland Siegwart Juan Nieto 《野外机器人技术杂志》2019,36(6):1041-1073
Visual localization in outdoor environments is subject to varying appearance conditions rendering it difficult to match current camera images against a previously recorded map. Although it is possible to extend the respective maps to allow precise localization across a wide range of differing appearance conditions, these maps quickly grow in size and become impractical to handle on a mobile robotic platform. To address this problem, we present a landmark selection algorithm that exploits appearance co‐observability for efficient visual localization in outdoor environments. Based on the appearance condition inferred from recently observed landmarks, a small fraction of landmarks useful under the current appearance condition is selected and used for localization. This allows to greatly reduce the bandwidth consumption between the mobile platform and a map backend in a shared‐map scenario, and significantly lowers the demands on the computational resources on said mobile platform. We derive a landmark ranking function that exhibits high performance under vastly changing appearance conditions and is agnostic to the distribution of landmarks across the different map sessions. Furthermore, we relate and compare our proposed appearance‐based landmark ranking function to popular ranking schemes from information retrieval, and validate our results on the challenging University of Michigan North Campus long‐term vision and LIDAR data sets (NCLT), including an evaluation of the localization accuracy using ground‐truth poses. In addition to that, we investigate the computational and bandwidth resource demands. Our results show that by selecting 20–30% of landmarks using our proposed approach, a similar localization performance as the baseline strategy using all landmarks is achieved. 相似文献
999.
Marc Walter Kostiantyn V. Kravchyk Cornelia Böfer Roland Widmer Maksym V. Kovalenko 《Advanced materials (Deerfield Beach, Fla.)》2018,30(15)
The pressing need for low‐cost and large‐scale stationary storage of electricity has led to a new wave of research on novel batteries made entirely of components that have high natural abundances and are easy to manufacture. One example of such an anode–electrolyte–cathode architecture comprises metallic aluminum, AlCl3:[EMIm]Cl (1‐ethyl‐3‐methylimidazolium chloride) ionic liquid and graphite. Various forms of synthetic and natural graphite cathodes have been tested in recent years in this context. Here, a new type of compelling cathode based on inexpensive pyrene polymers is demonstrated. During charging, the condensed aromatic rings of these polymers are oxidized, which is accompanied by the uptake of aluminum tetrachloride anions (AlCl4?) from the chloroaluminate ionic liquid. Discharge is the fast inverse process of reduction and the release of AlCl4?. The electrochemical properties of the polypyrenes can be fine‐tuned by the appropriate chemical derivatization. This process is showcased here by poly(nitropyrene‐co‐pyrene), which has a storage capacity of 100 mAh g?1, higher than the neat polypyrene (70 mAh g?1) or crystalline pyrene (20 mAh g?1), at a high discharge voltage (≈1.7 V), energy efficiency (≈86%), and cyclic stability (at least 1000 cycles). 相似文献
1000.
Réka Kothencz Roland Nagy László Bartha Judit Tóth Árpád Vágó 《Particulate Science and Technology》2018,36(7):887-890
Most petroleum reservoirs are subjected to Improved and Enhanced Oil Recovery (IOR and EOR) processes following secondary recovery. EOR involves the application of external forces and substances to improve the chemical and physical interactions in hydrocarbon reservoirs in order to improve preferable recovery conditions. The process of chemical flooding with solutions of polymers and surfactants can be used for developing oil exploitation. Studying the interaction between surfactants and polymers is indispensable for successful oil recovery. The interaction between non-ionic and anionic surfactants and polymers in ternary mixtures was examined at different concentrations and temperatures by dynamic light scattering and gel permeation chromatography. The hydrodynamic size of surfactant-polymer composites was higher than the particle size of individual components indicating a formation of associates. The size of associates was increased by increasing the concentration of the surfactants and the temperature. It could be supposed that the polymer formed a mixed micelle with the surfactants. Gel permeation chromatography has confirmed the increase in molecular weight of the associate formed by surfactants and polymers. 相似文献