• 제목/요약/키워드: Denmark

검색결과 279건 처리시간 0.025초

Role of Charges of the Surface-grafted Polymer Chains for Aqueous Lubrication at a Nonpolar Interface

  • Ron, Troels;Madsen, Jan Busk;Nikorgeorgos, Nikolaos;Lee, Seunghwan
    • Tribology and Lubricants
    • /
    • 제30권5호
    • /
    • pp.247-255
    • /
    • 2014
  • Charged polymer chains, i.e., polyelectrolytes, are known to show superior aqueous lubricating properties compared to those of neutral polymer chains, especially in brush conformation. This is primarily because of the incorporation of a large amount of counterions within the polymer layers and the consequently increased osmotic pressure. However, this effect is active only when the polymer chains remain immobilized even under tribostress, which is not realistic for high-contact pressure tribological applications, especially when they are irreversibly immobilized on tribopair surfaces. In contrast, with free polymers, which can be included as surface-active additives in the base lubricant (water), long-term lubricating performance based on "self-healing" properties is readily expected. In order to assess whether the superior aqueous lubricating properties of polyelectrolyte chains are valid for free polymers too, this study reviews recent studies on the tribological properties of many charged biopolymer and synthetic copolymers at a nonpolar, hydrophobic interface. In contrast to the irreversibly immobilized polyelectrolyte chains, free polyelectrolyte chains show inferior aqueous lubricating properties compared to their neutral counterparts owing to charge accumulation and the consequently impeded surface adsorption on the nonpolar surface. Nevertheless, bovine submaxillary mucin (BSM), a representative biopolymer, shows a sufficiently effective surface adsorption and aqueous lubricating capabilities even at neutral pH without losing the polyanionic characteristics.

Evaluating C-RAN Fronthaul Functional Splits in Terms of Network Level Energy and Cost Savings

  • Checko, Aleksandra;Avramova, Andrijana P.;Berger, Michael S.;Christiansen, Henrik L.
    • Journal of Communications and Networks
    • /
    • 제18권2호
    • /
    • pp.162-172
    • /
    • 2016
  • The placement of the complete baseband processing in a centralized pool results in high data rate requirement and inflexibility of the fronthaul network, which challenges the energy and cost effectiveness of the cloud radio access network (C-RAN). Recently, redesign of the C-RAN through functional split in the baseband processing chain has been proposed to overcome these challenges. This paper evaluates, by mathematical and simulation methods, different splits with respect to network level energy and cost efficiency having in the mind the expected quality of service. The proposed mathematical model quantifies the multiplexing gains and the trade-offs between centralization and decentralization concerning the cost of the pool, fronthaul network capacity and resource utilization. The event-based simulation captures the influence of the traffic load dynamics and traffic type variation on designing an efficient fronthaul network. Based on the obtained results, we derive a principle for fronthaul dimensioning based on the traffic profile. This principle allows for efficient radio access network with respect to multiplexing gains while achieving the expected users' quality of service.

Challenging the Hypothesis of de novo Biosynthesis of Bile Acids by Marine Bacteria

  • Tueros, Felipe Gonzalo;Ellabaan, Mostafa M. Hashim;Henricsson, Marcus;Vazquez-Uribe, Ruben;Backhed, Fredrik;Sommer, Morten Otto Alexander
    • 한국미생물·생명공학회지
    • /
    • 제50권1호
    • /
    • pp.102-109
    • /
    • 2022
  • Bile acids are essential molecules produced by vertebrates that are involved in several physiological roles, including the uptake of nutrients. Bacterial isolates capable of producing bile acids de novo have been identified and characterized. Such isolates may provide access to novel biochemical pathways suitable for the design of microbial cell factories. Here, we further characterized the ability of Maribacter dokdonensis, Dokdonia donghaensis, and Myroides pelagicus to produce bile acids. Contrary to previous reports, we did not observe de novo production of bile acids by these isolates. Instead, we found that these isolates deconjugated the amino acid moiety of bile acids present in the growth medium used in previous reports. Through genomic analysis, we identified putative bile salt hydrolases, which could be responsible for the different bile acid modifications observed. Our results challenge the hypothesis of de novo microbial bile acid production, while further demonstrating the diverse capacity of bacteria to modify bile acids.

Return on Leadership

  • Martensen, Anne;Gronholdt, Lars
    • International Journal of Quality Innovation
    • /
    • 제6권3호
    • /
    • pp.19-37
    • /
    • 2005
  • It is generally accepted that leadership is the foundation for creation of a company's business results. However, empirical evidence is lacking. This paper examines the relationship between leadership and key performance results based on a Return on Leadership Model. The model links Denison's four leadership traits to people results, customer results, and ultimately key performance results. Further specified, the model is a structural equation model with nine latent variables, each measured by a set of indicators, observed by survey questions. To validate the model, an empirical study was conducted, and 379 managers from medium-sized and large companies in Denmark participated. The estimation of the model shows that the model structure explains return on leadership very well, and the findings support the developed model. We are able to quantify the relationships from leadership to people results, customer results and key performance results and, in this way, the data presented here provide evidence that leadership is linked to key performance results. Several results and applications of the model are shown. The findings provide new knowledge about how leadership can be linked to performance, and how excellent leadership creates key performance results.

A direct XFEM formulation for modeling of cohesive crack growth in concrete

  • Asferg, J.L.;Poulsen, P.N.;Nielsen, L.O.
    • Computers and Concrete
    • /
    • 제4권2호
    • /
    • pp.83-100
    • /
    • 2007
  • Applying a direct formulation for the enrichment of the displacement field an extended finite element (XFEM) scheme for modeling of cohesive crack growth is developed. Only elements cut by the crack is enriched and the scheme fits within the framework of standard FEM code. The scheme is implemented for the 3-node constant strain triangle (CST) and the 6-node linear strain triangle (LST). Modeling of standard concrete test cases such as fracture in the notched three point beam bending test (TPBT) and in the four point shear beam test (FPSB) illustrates the performance. The XFEM results show good agreement with results obtained by applying standard interface elements in FEM and with experimental results. In conjunction with criteria for crack growth local versus nonlocal computation of the crack growth direction is discussed.

Recent Developments of Wave Energy Utilization in Denmark

  • Kofoed, J.P.;Frigaard, P.;Kramer, M.
    • 한국해양공학회:학술대회논문집
    • /
    • 한국해양공학회 2006년 창립20주년기념 정기학술대회 및 국제워크샵
    • /
    • pp.91-98
    • /
    • 2006
  • This paper aims at giving an overview of the developments researchers at the Department of Civil Engineering, Aalborg University, Denmark (DCE), have been involved in within the field of wave energy utilization in Denmark over the past decade. At first a general introduction is given followed by a more thorough description of three ongoing projects. These are Wave Dragon, Wave Star and Seawave Slot-cone Generator. Common for these projects are that they are being, or will soon be, tested in real sea and have benefited from the Danish Wave Energy Program. The work by the department on these projects involves substantial laboratory testing, numerical simulations and real sea prototype testing.

  • PDF

Stochastic procedures for extreme wave induced responses in flexible ships

  • Jensen, Jorgen Juncher;Andersen, Ingrid Marie Vincent;Seng, Sopheak
    • International Journal of Naval Architecture and Ocean Engineering
    • /
    • 제6권4호
    • /
    • pp.1148-1159
    • /
    • 2014
  • Different procedures for estimation of the extreme global wave hydroelastic responses in ships are discussed. Firstly, stochastic procedures for application in detailed numerical studies (CFD) are outlined. The use of the First Order Reliability Method (FORM) to generate critical wave episodes of short duration, less than 1 minute, with prescribed probability content is discussed for use in extreme response predictions including hydroelastic behaviour and slamming load events. The possibility of combining FORM results with Monte Carlo simulations is discussed for faster but still very accurate estimation of extreme responses. Secondly, stochastic procedures using measured time series of responses as input are considered. The Peak-over-Threshold procedure and the Weibull fitting are applied and discussed for the extreme value predictions including possible corrections for clustering effects.

A Comparison of Characteristics between Danish and Korean Farmhouses -In Reference to Farmhouse Plans, Use of Rooms including Furniture Arrangement, and Building Materials-

  • Choi, Jung-Shin
    • International Journal of Human Ecology
    • /
    • 제8권1호
    • /
    • pp.67-78
    • /
    • 2007
  • The aim of this paper was to compare differences and similarities of farmhouses between Denmark and Korea as a cross-cultural study. Farmhouses built during the 18th and 19th centuries in Denmark, and ones from Chosun Dynasty (AD. 1392-1910) in Korea were targets of this study. Literature study and field trips to districts and open-air museums in both countries were used. Field trips were carried out during summer of 2005 in Denmark, and fall of 2005 in Korea. Detailed comparisons focused on farmhouse plans, the use of rooms and furnishing, and building materials. As a conclusion, some differences were found between the two countries. In terms of farmhouse plans, square types with four wings, and parallel types were the most frequent forms in Denmark, while a few types, such as the "I", "L", "U" shapes and square types, were more frequently found in Korea. In Denmark, the most important room was the dwelling-room, in which daily family life took place. Every member of the family slept, ate, and worked here, and kept geese and young animals during the winter season. Therefore, this room was laid out in the center of the house. However, Anbang, the most important room in Korea, was not situated in the best part of the house. Instead, the Daechung-maru occupied the center and the best place because the daechung-maru, in which the ancestral ceremony was held, was thought of as more important than a place for live people. Also the use of rooms and furnishing was quite different between the two countries, reflecting each life style. Danish furnishings represented practical daily life, while Korean furnishings reflected more conceptual aspects. It might have resulted from Confucianism in the Chosun Dynasty, which ruled daily life and even influenced use of rooms and furnishings. In other word, philosophy influenced common peoples' daily life and living environment. With reference to building materials, there was rarely a difference between the two countries. Major materials for farmhouse were quite common, such as half-timbering wood and clay, but the difference was in bricks and roof coverings. Bricks were rarely used in Korean farmhouses, while rice-straw was rare for the roof of a Danish farmhouse. Of course, the choice of materials was strongly affected by the local surroundings and overall environment. This result can give some clues for design ideas when architects and interior designers plan housing that is adapted for local peoples. This kind of cross-cultural study can also contribute to one's understanding of foreign culture, especially in housing and culture. And, it can broaden one's insight of design ideas for designers who have to compete frequently with designers in foreign countries.

음향가진을 이용한 풍동터빈 날개의 운전형상 변형 분석 (Operational Modal Analysis of a Wind Turbine Wing Using Acoustical Excitation)

  • Herlufsen, H.;Konstantin-Hansen, H.;Moller, N.
    • 한국소음진동공학회:학술대회논문집
    • /
    • 한국소음진동공학회 2002년도 추계학술대회논문초록집
    • /
    • pp.385.1-385
    • /
    • 2002
  • Operational Modal Analysis also known as Ambient Modal Analysis has an increasing interest in mechanical cngineering. Especially on big structures where the excitation and not less important the determination of the forces is most often a problem. In a structure like a wind turbine wing where the modes occur both close in frequency and bi-directional the Ambient excitation has big advantages. (omitted)

  • PDF