Spiral tool paths for high-speed machining of 2D pockets with or without islands

Mikkel Abrahamsen 한국CDE학회 2019 Journal of computational design and engineering Vol.6 No.1

We describe new methods for the construction of spiral tool paths for high-speed machining. In the sim-plest case, our method takes a polygon as input and a number d > 0 and returns a spiral starting at a cen-tral point in the polygon, going around towards the boundary while morphing to the shape of the polygon. The spiral consists of linear segments and circular arcs, it is G1 continuous, it has no self-intersections, and the distance from each point on the spiral to each of the neighboring revolutions is at most d. Our method has the advantage over previously described methods that it is easily adjustable to the case where there is an island in the polygon to be avoided by the spiral. In that case, the spiral starts at the island and morphs the island to the outer boundary of the polygon. It is shown how to apply that method to make significantly shorter spirals in some polygons with no islands than what is obtained by conventional spiral tool paths. Finally, we show how to make a spiral in a polygon with multiple islands by connecting the islands into one island.

Novel Algal Cell Wall Hydrolyzing Enzymes from Algae-associated Microbes

Peter STOUGAARD,Mikkel SCHULTZ-JOHANSEN,Pernille KJERSGAARD BECH,Line CHRisTIANSEN 한국생물공학회 2017 한국생물공학회 학술대회 Vol.2017 No.4

Nonlinear fluid-structure interaction of bridge deck: CFD analysis and semi-analytical modeling

Christian Grinderslev,Mikkel Lubek,Zili Zhang 한국풍공학회 2018 Wind and Structures, An International Journal (WAS Vol.27 No.6

Nonlinear behavior in fluid-structure interaction (FSI) of bridge decks becomes increasingly significant for modern bridges with increasing spans, larger flexibility and new aerodynamic deck configurations. Better understanding of the nonlinear aeroelasticity of bridge decks and further development of reduced-order nonlinear models for the aeroelastic forces become necessary. In this paper, the amplitude-dependent and neutral angle dependent nonlinearities of the motion-induced loads are further highlighted by series of computational fluid dynamics (CFD) simulations. An effort has been made to investigate a semi-analytical time-domain model of the nonlinear motion induced loads on the deck, which enables nonlinear time domain simulations of the aeroelastic responses of the bridge deck. First, the computational schemes used here are validated through theoretically well-known cases. Then, static aerodynamic coefficients of the Great Belt East Bridge (GBEB) cross section are evaluated at various angles of attack, leading to the so-called nonlinear backbone curves. Flutter derivatives of the bridge are identified by CFD simulations using forced harmonic motion of the cross-section with various frequencies. By varying the amplitude of the forced motion, it is observed that the identified flutter derivatives are amplitude-dependent, especially for A_2^* and H_2^* parameters. Another nonlinear feature is observed from the change of hysteresis loop (between angle of attack and lift/moment) when the neutral angles of the cross-section are changed. Based on the CFD results, a semi-analytical time-domain model for describing the nonlinear motion-induced loads is proposed and calibrated. This model is based on accounting for the delay effect with respect to the nonlinear backbone curve and is established in the state-space form. Reasonable agreement between the results from the semi-analytical model and CFD demonstrates the potential application of the proposed model for nonlinear aeroelastic analysis of bridge decks.

Thoracodorsal artery flaps for breast reconstruction-the variants and its approach

Thomsen, Jorn Bo,Rindom, Mikkel Borsen,Rancati, Alberto,Angrigiani, Claudio Korean Society of Plastic and Reconstructive Surge 2021 Archives of Plastic Surgery Vol.48 No.1

Thoracodorsal artery (TDA) flaps, ranging from the vascular-pedicled thoracodorsal artery perforator (TDAP) flap, the propeller TDAP flap, and the muscle-sparing latissimus dorsi (MSLD) flap to the conventional latissimus dorsi (LD) flap and the extended LD flap, can all be used for breast reconstruction. The aim of this paper and review is to share our experiences and recommendations for procedure selection when applying TDA-based flaps for breast reconstruction. We describe the different surgical techniques and our thoughts and experience regarding indications and selection between these procedures for individual patients who opt for breast reconstruction. We have performed 574 TDA flaps in 491 patients: 60 extended LD flaps, 122 conventional LD flaps, two MSLD flaps, 233 propeller TDAP flaps, 122 TDAP flaps, and 35 free contralateral TDAP flaps for stacked TDAP breast reconstruction. All the TDA flaps are important flaps for reconstruction of the breast. The LD flap is still an option, although we prefer flaps without muscle when possible. The vascular-pedicled TDAP flap is an option for experienced surgeons, and the propeller TDAP flap can be used in most reconstructive cases of the breast, although a secondary procedure is often necessary for correction of the pedicle bulk. The extended LD flap is an option for women with a substantial body mass index, although it is associated with the highest morbidity of all the TDA flaps. The MSLD flap can be used if the perforators are small or if dissection of the perforators is assessed to be hazardous.

TESTING A MODEL OF DESTINATION IMAGE FORMATION: APPLICATION OF NONPARAMETRIC BAYESIAN RELATIONAL MODELING TO DESTINATION IMAGE ANALYSIS

Fumiko Kano Glückstad,Mikkel N. Schmidt,Morten Mørup 글로벌지식마케팅경영학회 2018 Global Marketing Conference Vol.2018 No.07

This presentation introduces a methodological framework that analyzes a model of destination image formation (Baloglu & McCleary 1999; Beerli & Martin 2004). Specifically, the main aims of this study are to investigate what type of stimulus factors (information sources) are connected to the formation of destination image, and to explore if there is a connection between their strength of willingness to visit a destination and their patterns to associate with the destination. The study employs an advanced nonparametric Bayesian relational model (Glückstad, Herlau, Schmidt, Rzepka, Araki and Mørup 2013; Mørup, Glückstad, Herlau & Schmidt, 2014) for a two-steps analysis . The first step attempts to segment consumers according to patterns of attributes consumers associate with three arbitrary selected destinations. The second step statistically analyzes latent structural patterns per segment by contrasting two independent datasets, one consisting of information sources and members of a segment and another consisting of destination attributes and the members of the segment. The results of two-steps analysis demonstrated that patterns of attributes respondents associate with the three selected destinations differ across individuals and the applied method enabled to segment respondents according to the differences, and consumers’ associations, their willingness to visit the destinations and types of information sources they have accessed to learn about the destinations are connected to each other.

Platform Thinking within the Third Generation Science Park Concept: Emerging Cases from Finland and the Netherlands

Ilkka Kakko,Kari Mikkelä 세계과학도시연합 2016 World Technopolis Review Vol.5 No.1

This paper is intended as an opening of a dialog on how to apply platform thinking in the development of innovation environments. It will briefly describe a new STP (Science and Technology Park) concept called 3GSP (Third Generation Science Park), which is gaining momentum in Finland. The paper explains the fundamental changes that are currently taking place in the global innovation environment and explains why platform thinking is becoming an essential element in ecosystem development. The theoretical background and classifications of platforms are described and the benefits to be gained from STP perspective are highlighted. The paper emphasizes especially the role of so called ‘competence platforms’ and explains the main characteristics of a fully working competence platform. The role of competence platforms in understanding serendipity and as a fundamental factor in building the team is also highlighted. The paper analyses from STP perspective several practical examples, where platform thinking supports the emergence of new innovation environments, including Urban Mill (Finland) and Meetberlage (Netherlands). The requirements for comprehensive competence platform services are presented and their potential to support community building and therefore ecosystem development is illustrated. This analysis will provide STP practitioners with new models for applying platform thinking and will help to establish co-creation, open innovation and serendipity management practices. The case studies presented will help STP management teams to evaluate the benefits of competence platforms in different contexts.

The Impact of Testicular Torsion on Testicular Function

Jacobsen Frederik M.,Rudlang Trine M.,Fode Mikkel,Østergren Peter B.,Sønksen Jens,Ohl Dana A.,Jensen Christian Fuglesang S. 대한남성과학회 2020 The World Journal of Men's Health Vol.38 No.3

Torsion of the spermatic cord is a urological emergency that must be treated with acute surgery. Possible long-term effects of torsion on testicular function are controversial. This review aims to address the impact of testicular torsion (TT) on the endocrine- and exocrine-function of the testis, including possible negative effects of torsion on the function of the contralateral testis. Testis tissue survival after TT is dependent on the degree and duration of TT. TT has been demonstrated to cause long-term decrease in sperm motility and reduce overall sperm counts. Reduced semen quality might be caused by ischemic damage and reperfusion injury. In contrast, most studies find endocrine parameters to be unaffected after torsion, although few report minor alterations in levels of gonadotropins and testosterone. Contralateral damage after unilateral TT has been suggested by histological abnormalities in the contralateral testis after orchiectomy of the torsed testis. The evidence is, however, limited as most human studies are small case-series. Theories as to what causes contralateral damage mainly derive from animal studies making it difficult to interpret the results in a human context. Large long-term follow-up studies are needed to clearly uncover changes in testicular function after TT and to determine the clinical impact of such changes.

The Skallingen spit, Denmark: birth of a back-barrier saltmarsh

Bartholdy, Jesper,Brivio, Lara,Bartholdy, Anders,Kim, Daehyun,Fruergaard, Mikkel Springer-Verlag 2018 Geo-marine letters Vol.38 No.2

<P>The formation and evolution of a modern saltmarsh platform on the barrier spit Skallingen in the northernmost part of the Wadden Sea was investigated through historical map records, 12 orthophotos covering the period from 1945 to 2012, sediment cores and cross-sectional creek profiles. The barrier spit, which constitutes the foundation of the saltmarsh platform, formed in about 50 years in the seventeenth century. After its formation the spit was left as a bare sandflat for about 200 years. Along with the development of foredunes, an increased availability of fine-grained sediment and establishment of vegetation in the beginning of the 1890s, the saltmarsh area formed in about 100 years, while the development of a large system of saltmarsh creeks took place in just ca. 50 years. The development of the drainage network, saltmarsh creek morphology and sedimentology during the saltmarsh formation are described in detail and analysed with special attention to the transformation rate from bare sandflat to a genuine vegetation-covered back-barrier saltmarsh.</P>

Porous Nafion membranes

Joseph, Dickson,Bü,sselmann, Julian,Harms, Corinna,Henkensmeier, Dirk,Larsen, Mikkel Juul,Dyck, Alexander,Jang, Jong Hyun,Kim, Hyoung-Juhn,Nam, Suk Woo Elsevier 2016 Journal of membrane science Vol.520 No.-

<P><B>Abstract</B></P> <P>By varying the amount of porogene (<I>ortho</I>-dichlorobenzene, ODB), and optimization of the dispersion process, two types of solvent cast Nafion membranes with an equivalent weight of 1100g/mol sulfonic acid can be obtained reproducibly. One type is a dense membrane with a porous layer on one surface. The other membrane type shows a novel structure, consisting of small closed pores throughout the membrane and a single layer of large open pores on one side. In addition, some membranes showed a structural morphology between these two types, a membrane with a dense part and a porous part on top of each other. The latter membrane structure was not fully reproducible yet, but probably could be by carefully adjusting the formulation of the casting solution. Also the effect of the casting temperature on the morphology is shown. Fully porous membranes were characterized for their water permeability, ion conductivity, mechanical properties, their performance in the fuel cell and the hydrogen crossover. While the fully porous membranes are not expected to be part of a real fuel cell, we expect that the new morphologies will inspire applied research, e.g. in which the pores are filled with electrolyte or material or a catalyst is blended into the polymer.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Nafion membranes with three different morphologies were prepared. </LI> <LI> a) dense Nafion membranes with a porous surface, based on EW 1100. </LI> <LI> b) mixed dense/porous membranes. </LI> <LI> c) fully porous membranes with closed pores and larger open pores on the surface. </LI> <LI> Membranes were prepared in a single step (solution casting). </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Blend membranes of polybenzimidazole and an anion exchange ionomer (FAA3) for alkaline water electrolysis: Improved alkaline stability and conductivity

Konovalova, Anastasiia,Kim, Hyemi,Kim, Sangwon,Lim, Ahyoun,Park, Hyun Seo,Kraglund, Mikkel Rykær,Aili, David,Jang, Jong Hyun,Kim, Hyoung-Juhn,Henkensmeier, Dirk Elsevier 2018 Journal of membrane science Vol.564 No.-

<P><B>Abstract</B></P> <P>Anion exchange membranes (AEMs) conduct selectively hydroxide ions, while KOH doped polybenzimidazole is an ion-solvating polymer, conducting both potassium and hydroxide ions. In this work, meta-polybenzimidazole (mPBI) was blended with FAA3, a commercially available AEM, in the ratios of 2:1, 3:1, 4:1, 5:1 and 1:0. Doping was done by immersion in 0, 10, 15, 20, 25 and 30 wt% KOH solutions, giving rise to 30 membranes which were analyzed for their swelling behavior during doping, there composition (polymer, water, KOH), their mechanical properties and their through-plane conductivity in KOH solutions. Especially PF-41 showed higher tensile strength and Young's modulus than mPBI under all tested KOH concentrations. The highest conductivity of 166 mS cm<SUP>−1</SUP> was observed for PF-51 doped in 25% KOH, 80% higher than for mPBI. In an alkaline stability test, blend membranes showed higher tensile strength, Young's modulus and lower weight loss than mPBI after 4 weeks at 85 °C in 25 wt% KOH solution. PF-31 and PF-41 were also tested in an electrolysis cell, where they showed cell resistance comparable to mPBI. Because systems without cathode feed can be quite efficient, the permeability of membranes for KOH solutions was investigated.</P> <P><B>Highlights</B></P> <P> <UL> <LI> PBI and FAA3 were blended and doped with KOH solution. </LI> <LI> Composition (polymer, water, KOH) was analyzed. </LI> <LI> Blends show higher tensile strength and conductivity than PBI. </LI> <LI> Blends show higher alkaline stability (lower weight loss, higher tensile strength). </LI> <LI> In the electrolyzer, performance of the blends was similar to that of PBI. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>