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- 저자 : Jørgensen, U. G. (검색결과 39 건)
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Jørgensen, Mathias,Lee, Young-Su,Bjerring, Morten,Jepsen, Lars H.,Akbey, Ü,mit,Cho, Young Whan,Jensen, Torben R. The Royal Society of Chemistry 2018 Dalton Transactions Vol.47 No.46
<P>The new compound Sr(BH4)2(NH3BH3)2 has been synthesized and characterized with <I>in situ</I> powder X-ray diffraction and fast (28 or 60 kHz) magic angle spinning <SUP>1</SUP>H, <SUP>11</SUP>B and <SUP>15</SUP>N NMR and structurally optimized with density functional theory calculations. This investigation reveals complex structural rearrangements for this compound as a function of temperature. A room temperature orthorhombic polymorph, α-Sr(BH4)2(NH3BH3)2, with the space group symmetry <I>Pbca</I>, has been determined with a layered structure of alternating ammonia borane and Sr(BH4)2, partially stabilized by dihydrogen bonding. Surprisingly the crystal symmetry is lowered upon heating, as evidenced both by <I>in situ</I> synchrotron powder X-ray diffraction and <SUP>11</SUP>B MAS NMR data, resulting in an intermediate polymorph, β′-Sr(BH4)2(NH3BH3)2, present from ∼65 to 115 °C. β-Sr(BH4)2(NH3BH3)2, a sub structure of the β′-polymorph showing higher symmetry with the space group symmetry <I>Aba</I>2, forms upon further heating. <I>Ab initio</I> molecular dynamics simulations show that the ammonia borane molecule can dynamically alternate between a bidentate and a tridentate coordination to Sr at finite temperature. The dynamic properties of the ammonia borane molecule in the solid state are suggested to cause the observed structural complexity. Based on simultaneous thermogravimetric analysis, differential scanning calorimetry and mass spectrometry, the decomposition of the compound was investigated showing a stabilization of ammonia borane in the structure relative to other metal borohydride ammonia boranes and neat ammonia borane.</P>
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On the nonlinear structural analysis of wind turbine blades using reduced degree-of-freedom models
K. Holm-Jørgensen,J.W. Stærdahl,S.R.K. Nielsen 국제구조공학회 2008 Structural Engineering and Mechanics, An Int'l Jou Vol.28 No.1
Wind turbine blades are increasing in magnitude without a proportional increase of stiffness for which reason geometrical and inertial nonlinearities become increasingly important. Often these effects are analysed using a nonlinear truncated expansion in undamped fixed base mode shapes of a blade, modelling geometrical and inertial nonlinear couplings in the fundamental flap and edge direction. The purpose of this article is to examine the applicability of such a reduced-degree-of-freedom model in predicting the nonlinear response and stability of a blade by comparison to a full model based on a nonlinear co-rotating FE formulation. By use of the reduced-degree-of-freedom model it is shown that under strong resonance excitation of the fundamental flap or edge modes, significant energy is transferred to higher modes due to parametric or nonlinear coupling terms, which influence the response and stability conditions. It is demonstrated that the response predicted by such models in some cases becomes instable or chaotic. However, as a consequence of the energy flow the stability is increased and the tendency of chaotic vibrations is reduced as the number of modes are increased. The FE model representing the case of infinitely many included modes, is shown to predict stable and ordered response for all considered parameters. Further, the analysis shows that the reduced-degree-of-freedom model of relatively low order overestimates the response near resonance peaks, which is a consequence of the small number of included modes. The qualitative erratic response and stability prediction of the reduced order models take place at frequencies slightly above normal operation. However, for normal operation of the wind turbine without resonance excitation 4 modes in the reduced-degree-of-freedom model perform acceptable.
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Technical Barriers, Import Licenses and Tariffs as Means of Limiting Market Access
( Jan G. Jørgensen ),( Philipp J. H. Schroder ) 세종대학교 경제통합연구소 (구 세종대학교 국제경제연구소) 2006 Journal of Economic Integration Vol.21 No.1
Technical barriers (standards), import licenses and tariffs may be deployed as means of limiting the market access of foreign firms. The present paper examines these measures in a setting of monopolistic competition. We find that, if protection focuses predominantly on the number of foreign firms accessing the domestic market, a technical barrier (an import license) may dominate a tariff (tariff and a technical barrier) in terms of consumer welfare, even when tariff revenues are fully redistributed. However, if protection pays sucfficient focus on limiting the total import volume, then tariffs are the preferred means of protection. Within the model, reductions in technical barriers and tariffs, the removal of licensing schemes, and a harmonization of standards are all welfare-improving policies.
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Market Integration and Industrial Specialization on a Monopolistic Competitive Market
Hansen, JØrgen Drud,JØrgensen , Jan Guldager 세종대학교 국제경제연구소 2001 Journal of Economic Integration Vol.16 No.3
This paper examines the relationship between market integration and product diversification in a Chamberlinian model of monopolistic competition. In the first version of the model, production of the firm is organised in activities producing either one or two horizontally differentiated product-variants. The cost functions show both scale and scope economies. Market integration is illustrated by an increase in the market size. For increasing market size, each firm shifts from producing tow variants to producing one variant only at a certain threshold value of market size. Passing this threshold value the firm size measured by total output changes discontinuously leaving the effect on firm size ambiguous. For specific specification of the perceived demand of the individual firm hysteresis of the industrial structure may appear in the sense that the threshold value of the market size for shifting from two to one variant production exceeds that of the threshold value of market size of shifting from one to two variants. In the last part of the paper, the model is generalised to a continuum of variants and it is shown that an increase of the market size reduces the number of variants produced by each firm, whereas the hysteresis phenomenon disappears.
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Bozza, V.,Dominik, M.,Rattenbury, N. J.,Jørgensen, U. G.,Tsapras, Y.,Bramich, D. M.,Udalski, A.,Bond, I. A.,Liebig, C.,Cassan, A.,Fouqué,, P.,Fukui, A.,Hundertmark, M.,Shin, I.‐,G.,Lee, S. Blackwell Publishing Ltd 2012 MONTHLY NOTICES- ROYAL ASTRONOMICAL SOCIETY Vol.424 No.2
<P><B>ABSTRACT</B></P><P>The microlensing event OGLE‐2008‐BLG‐510 is characterized by an evident asymmetric shape of the peak, promptly detected by the Automated Robotic Terrestrial Exoplanet Microlensing Search (ARTEMiS) system in real time. The skewness of the light curve appears to be compatible both with binary‐lens and binary‐source models, including the possibility that the lens system consists of an M dwarf orbited by a brown dwarf. The detection of this microlensing anomaly and our analysis demonstrate that: (1) automated real‐time detection of weak microlensing anomalies with immediate feedback is feasible, efficient and sensitive, (2) rather common weak features intrinsically come with ambiguities that are not easily resolved from photometric light curves, (3) a modelling approach that finds all features of parameter space rather than just the ‘favourite model’ is required and (4) the data quality is most crucial, where systematics can be confused with real features, in particular small higher order effects such as orbital motion signatures. It moreover becomes apparent that events with weak signatures are a silver mine for statistical studies, although not easy to exploit. Clues about the apparent paucity of both brown‐dwarf companions and binary‐source microlensing events might hide here.</P>
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Frederik C. Gulmark Hansen,Mads Gustaf Jørgensen,Jens Ahm Sørensen 한국유방암학회 2023 Journal of breast cancer Vol.26 No.1
Purpose: Breast cancer-related lymphedema (BCRL) is a chronic, progressive side effect of breast cancer treatment, occurring in one-third of patients treated with axillary lymph node dissection and nodal radiotherapy. Cluster of differentiation 4-positive (CD4+) cells plays a key role in BCRL by facilitating inflammation and inhibiting lymphangiogenesis. Tacrolimus is an anti-inflammatory and immunosuppressive macrolide that targets CD4+ cells. Treatment of lymphedema with topical tacrolimus has revealed promising results in preclinical trials. This clinical trial was aimed at evaluating the feasibility, safety, and effect of tacrolimus in women with stage I or II BCRL, according to the International Society of Lymphology. Methods: We conducted this open-label, single-arm, phase II pilot trial from September 2020 to April 2021. Eighteen women with BCRL stage I or II BCRL were treated with topical tacrolimus for 6 months and followed up at 3 and 6 months. The primary outcome was arm volume, and secondary outcomes were the lymphedema index (L-Dex), health-related quality of life (HRQoL), lymph flow and function, and safety and feasibility of the trial design. Results: The mean lymphedema arm volume and L-Dex reduced significantly by 130.44 ± 210.13 mL (p < 0.05; relative reduction: 3.6%) and 3.54 ± 4.98 (p < 0.05), respectively, and health-related quality of life scores was improved significantly (p < 0.05). According to the MD Anderson scale, in terms of lymph flow and function, three patients (16.7%) showed improvement, while none showed worsening. Lymph flow or function showed no change according to the Arm Dermal Backflow scale. Conclusion: In this trial, treatment with tacrolimus was safe and feasible in women with stage I or II BCRL. Tacrolimus alleviated BCRL in terms of improved arm volume, L-Dex, and HRQoL. Assessments of lymph flow and function were positive, although inconclusive. Larger randomized controlled trials are required to verify these findings. Trial Registration: ClinicalTrials.gov Identifier: NCT04541290
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Green, Joel D.,Evans II, Neal J.,Jørgensen, Jes K.,Herczeg, Gregory J.,Kristensen, Lars E.,Lee, Jeong-Eun,Dionatos, Odysseas,Yildiz, Umut A.,Salyk, Colette,Meeus, Gwendolyn,Bouwman, Jeroen,Visser, Ruu IOP Publishing 2013 The Astrophysical journal Vol.770 No.2
<P>We present 50-210 mu m spectral scans of 30 Class 0/I protostellar sources, obtained with Herschel-PACS, and 0.5-1000 mu m spectral energy distributions, as part of the Dust, Ice, and Gas in Time Key Program. Some sources exhibit up to 75 H2O lines ranging in excitation energy from 100 to 2000 K, 12 transitions of OH, and CO rotational lines ranging from J = 14 -> 13 up to J = 40 -> 39. [O I] is detected in all but one source in the entire sample; among the sources with detectable [O I] are two very low luminosity objects. The mean 63/145 mu m [O I] flux ratio is 17.2 +/- 9.2. The [O I] 63 mu m line correlates with L-bol, but not with the time-averaged outflow rate derived from low-J CO maps. [C II] emission is in general not local to the source. The sample L-bol increased by 1.25 (1.06) and T-bol decreased to 0.96 (0.96) of mean (median) values with the inclusion of the Herschel data. Most CO rotational diagrams are characterized by two optically thin components (< N > = ( 0.70 +/- 1.12) x 10(49) total particles). N-CO correlates strongly with L-bol, but neither T-rot nor N-CO(warm)/N-CO(hot) correlates with L-bol, suggesting that the total excited gas is related to the current source luminosity, but that the excitation is primarily determined by the physics of the interaction (e.g., UV-heating/shocks). Rotational temperatures for H2O (< T-rot > = 194 +/- 85 K) and OH (< T-rot > = 183 +/- 117 K) are generally lower than for CO, and much of the scatter in the observations about the best fit is attributed to differences in excitation conditions and optical depths among the detected lines.</P>
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Evans, D. F.,Southworth, J.,Smalley, B.,Jørgensen, U. G.,Dominik, M.,Andersen, M. I.,Bozza, V.,Bramich, D. M.,Burgdorf, M. J.,Ciceri, S.,D’Ago, G.,Figuera Jaimes, R.,Gu, S.-H.,Hinse, T. C.,Henning, Th Springer-Verlag 2018 Astronomy and astrophysics Vol.610 No.-
<P><I>Context.</I> The formation and dynamical history of hot Jupiters is currently debated, with wide stellar binaries having been suggested as a potential formation pathway. Additionally, contaminating light from both binary companions and unassociated stars can significantly bias the results of planet characterisation studies, but can be corrected for if the properties of the contaminating star are known.</P><P><I>Aim.</I> We search for binary companions to known transiting exoplanet host stars, in order to determine the multiplicity properties of hot Jupiter host stars. We also search for and characterise unassociated stars along the line of sight, allowing photometric and spectroscopic observations of the planetary system to be corrected for contaminating light.</P><P><I>Methods.</I> We analyse lucky imaging observations of 97 Southern hemisphere exoplanet host stars, using the Two Colour Instrument on the Danish 1.54 m telescope. For each detected companion star, we determine flux ratios relative to the planet host star in two passbands, and measure the relative position of the companion. The probability of each companion being physically associated was determined using our two-colour photometry.</P><P><I>Results.</I> A catalogue of close companion stars is presented, including flux ratios, position measurements, and estimated companion star temperature. For companions that are potential binary companions, we review archival and catalogue data for further evidence. For WASP-77AB and WASP-85AB, we combine our data with historical measurements to determine the binary orbits, showing them to be moderately eccentric and inclined to the line of sight (and hence planetary orbital axis). Combining our survey with the similar Friends of Hot Jupiters survey, we conclude that known hot Jupiter host stars show a deficit of high mass stellar companions compared to the field star population; however, this may be a result of the biases in detection and target selection by ground-based surveys.</P>
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Junction Temperature Estimation for an Advanced Active Power Cycling Test
U. M. Choi,F. Blaabjerg,S. Jørgensen 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
On-state collector-emitter voltage (VCE) is a good indicator to determine the wear-out condition of power device modules. Further, it is a one of the Temperature Sensitive Electrical Parameters (TSEPs) and thus can be used for junction temperature estimation. In this paper, the junction temperature estimation method using on-state VCE for an advanced active power cycling test is proposed. The concept of the advanced power cycling test is explained first. Afterwards the junction temperature estimation method using on-state VCE and current is presented. Further, the method to improve the accuracy of the maximum junction temperature estimation is also proposed. Finally, the validity and effectiveness of the proposed method is confirmed by experimental results.
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