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作者： Castillo, E. Grande, Z. Moraga, P. Nogal, M. O'Connor, A.J. Royal Academy of Engineering Spain Department of Applied Mathematics and Computational Sciences University of Cantabria Santander Spain Pontificia Universidad Católica de Valparaíso Chile Trinity College Dublin Ireland

Multiple track lines are the only satisfactory solution for high speed railway lines when demand is high. However, in several countries double track high speed lines are being built for low demand lines, which are very expensive and inadequate solutions. This paper presents alternate double-single-track (ADST) lines as an alternative to doubletrack lines. The idea consists of using single-track where the infrastructure is very expensive (tunnels and viaducts) and double-track where it is cheaper (smooth orography) combined with small changes in departure times so that trains may cross in the double-track segments with no reduction in travel times. The solution is shown to be very efficient for intermediate traffic demands and the construction and maintenance costs are substantially reduced (close to 40%). A linear programming program is given that (1) decides the optimal sequence of single and double-tracks to be constructed and (2) optimizes the timetables for a given demand. The method can also be applied to combine high speed tracks with conventional existing tracks, where the conventional ones are used mainly for train crossing and circulation of slow and freight trains. These solutions produce very important savings (close to 90%) with very reasonable travel times. The lines Palencia-Santander in Spain, the Santiago-Valparaíso-Viña del Mar in Chile and the Dublin-Belfast in Ireland are used to illustrate both proposals and to demonstrate that they are very interesting alternatives in some practical cases. © Civil-Comp Press, 2016.

关键词： Travel time

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computational study to determine redox potential of nitroxide radical and their derivatives compounds along with their analysis as redox-coupe in dye sensitized solar cell’s (DSSC)

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AIP Conference Proceedings 2018年第1期2049卷

作者： Zahra R. Puteri Yuly Kusumawati Athar L. Ivansyah Muhamad A. Martoprawiro 1Chemistry Department Faculty of Natural Sciences Institut Tehnologi Sepuluh Nopember (ITS) ITS Campus Sukolilo Surabaya East Java 60111 Indonesia 2Master Program in Computational Science Faculty of Mathematics and Natural Science Institut Tehnologi Bandung (ITB) Jl. Ganesha 10 Bandung West Java 401232 Indonesia 3Department Chemistry Faculty of Mathematics and Natural Science Institut Tehnologi Bandung Jl. Ganesha 10 Bandung West Java 401232 Indonesia

The determination of redox potential (E°) was performed by computational study with variation of correlation-function B3LYP, CAM-B3LYP and ωb97-XD for pipiridine, azaadamantane and azaphenalene of nitroxide radical compounds with DFT method. The basis set of 6-13G(d) was used for geometry optimization and frequency calculation. The results showed that the calculation of redox potential with CAM-B3LYP method has the smallest error that is 1.191%. 4-hydroxy TEMPO compound with E° of 0.754 V (vs NHE) is promising to be used as a redox couple on DSSC’s application due to Voc, ΔEregeneration and RCT value consideration.

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Extremely Large Magnetoresistance in a Topological Semimetal Candidate Pyrite PtBi2

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Physical Review Letters 2017年第25期118卷 256601-256601页

作者： Wenshuai Gao Ningning Hao Fa-Wei Zheng Wei Ning Min Wu Xiangde Zhu Guolin Zheng Jinglei Zhang Jianwei Lu Hongwei Zhang Chuanying Xi Jiyong Yang Haifeng Du Ping Zhang Yuheng Zhang Mingliang Tian Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions High Magnetic Field Laboratory Chinese Academy of Sciences Hefei 230031 Anhui People’s Republic of China. Department of Physics University of Science and Technology of China Hefei 230026 People’s Republic of China Institute of Applied Physics and Computational Mathematics Beijing 100088 People’s Republic of China Beijing Computational Science Research Center Beijing 100193 People’s Republic of China Collaborative Innovation Center of Advanced Microstructures Nanjing University Nanjing 210093 People’s Republic of China

While pyrite-type PtBi2 with a face-centered cubic structure has been predicted to be a three-dimensional (3D) Dirac semimetal, experimental study of its physical properties remains absent. Here we report the angular-dependent magnetoresistance measurements of a PtBi2 single crystal under high magnetic fields. We observed extremely large unsaturated magnetoresistance (XMR) up to (11.2×106)% at T=1.8 K in a magnetic field of 33 T, which is comparable to the previously reported Dirac materials, such as WTe2, LaSb, and NbP. The crystals exhibit an ultrahigh mobility and significant Shubnikov–de Hass quantum oscillations with a nontrivial Berry phase. The analysis of Hall resistivity indicates that the XMR can be ascribed to the nearly compensated electron and hole. Our experimental results associated with the ab initio calculations suggest that pyrite PtBi2 is a topological semimetal candidate that might provide a platform for exploring topological materials with XMR in noble metal alloys.

关键词： Fermi surface Magnetotransport Semimetals Single crystal materials Topological materials Shubnikov-de Haas effect

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Comparative study of some numerical methods to solve a 3D advection-diffusion equation

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AIP Conference Proceedings 2017年第1期1863卷

作者： A. R. Appadu J. K. Djoko H. H. Gidey 1Department of Mathematics and Applied Mathematics University of Pretoria Pretoria 0002 South Africa 2Department of Computational Sciences Aksum University Aksum 1010 Tigray Ethiopia

In this work, three finite difference methods have been used to solve a three dimensional advection-diffusion equation with given initial and boundary conditions. The three methods are fourth order finite difference method, Crank-Nicolson and Implicit Chapeau Function. We compare the performance of the methods by computing L2 error, L∞ error and some performance indices such as mass distribution ratio (MDR), mass conservation ratio (MCR), total mass and R2 which is a measure of total variation in particle distribution.

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Corrigendum to “A stable and conservative interface treatment of arbitrary spatial accuracy” [J. Comput. Phys. 148 (1999) 341–365]

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Journal of computational Physics 2017年 351卷 534-534页

作者： Mark H. Carpenter Jan Nordström David Gottlieb Computational Aerosciences Branch NASA Langley Research Center Hampton VA 23681 USA Department of Mathematics Computational Mathematics Linköping University SE-581 83 Linköping Sweden Division of Applied Mathematics Brown University Providence RI 02912 USA

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Quantum interference in laser-induced nonsequential double ionization

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Physical Review A 2017年第3期96卷 032511-032511页

作者： Wei Quan XiaoLei Hao YanLan Wang YongJu Chen ShaoGang Yu SongPo Xu ZhiLei Xiao RenPing Sun XuanYang Lai ShiLin Hu MingQing Liu Zheng Shu XiaoDong Wang WeiDong Li Wilhelm Becker XiaoJun Liu Jing Chen State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics and Center for Cold Atom Physics Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences Wuhan 430071 China Institute of Theoretical Physics and Department of Physics Shanxi University 030006 Taiyuan China School of Physics University of Chinese Academy of Sciences Beijing 100080 China HEDPS Center for Applied Physics and Technology Beijing 100084 China Institute of Applied Physics and Computational Mathematics P.O. Box 8009 Beijing 100088 China College of Physics and Electronic Engineering Northwest Normal University Lanzhou 730070 China Max-Born-Institut Max-Born-Strasse 2a 12489 Berlin Germany National Research Nuclear University MEPhI Kashirskoe Shosse 31 115409 Moscow Russia

Quantum interference plays an important role in various intense-laser-driven atomic phenomena, e.g., above-threshold ionization and high-order-harmonic generation, and provides a useful tool in ultrafast imaging of atomic and molecular structure and dynamics. However, it has eluded observation in nonsequential double ionization (NSDI), which serves as an ideal prototype to study electron-electron correlation. Thus far, NSDI usually could be well understood from a semiclassical perspective, where all quantum aspects have been ignored after the first electron has tunneled. Here we perform coincidence measurements for NSDI of xenon subject to laser pulses at 2400 nm. It is found that the intensity dependence of the asymmetry parameter between the yields in the second and fourth quadrants and those in the first and third quadrants of the electron-momentum-correlation distributions exhibits a peculiar fast oscillatory structure, which is beyond the scope of the semiclassical picture. Our theoretical analysis indicates that this oscillation can be attributed to interference between the contributions of different excited states in the recollision-excitation-with-subsequent-ionization channel. Our work demonstrates the significant role of quantum interference in NSDI and may create an additional pathway towards manipulation and imaging of the ultrafast atomic and molecular dynamics in intense laser fields.

关键词： Multiphoton or tunneling ionization & excitation Atomic & molecular beams Atoms Femtosecond laser spectroscopy Semiclassical methods Strong-field approximation

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Low-energy electron elastic scattering and impact ionization with hydrogenlike helium in Debye plasmas

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Physical Review A 2017年第3期96卷 032707-032707页

作者： Jun Li Song Bin Zhang Bang Jiao Ye Jian Guo Wang R. K. Janev State Key Laboratory of Particle Detection and Electronics Department of Modern Physics University of Science and Technology of China 230026 Hefei People's Republic of China School of Physics and Information Technology Shaanxi Normal University 710119 Xi'an China Institute of Applied Physics and Computational Mathematics P.O. Box 8009 Beijing 100088 China Macedonian Academy of Sciences and Arts P.O. Box 428 1000 Skopje Macedonia

Low-energy electron elastic scattering and impact ionization with hydrogenlike helium in Debye plasmas have been investigated by employing the exterior complex scaling method. The interactions between charged particles in the plasmas have been represented by Debye-Hückel potentials. The 1s−1s elastic collision strengths below the n=2 excitation threshold of He+ dominated by resonance structures are calculated for different screening lengths. As the screening strength increases, the resonance peaks studied [2(1,0)2+1Se,3Po,1De, and 2(0,1)2+1Po] exhibit blueshifts and then redshifts with a further increase of the screening strength, which results in dramatic changes of the collision strengths. It is found that these dynamic variation features of the resonances are related to the changes of energy levels of He+ in the screened potential and geometric configurations of resonances. Triple-differential-ionization cross sections in coplanar geometries at 6-Ry incident electron energy are also reported, significant changes are observed with varying screening length.

关键词： Electron & positron scattering

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A demonstration of improved constraints on primordial gravitational waves with delensing

arXiv

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arXiv 2020年

作者： Ade, P.A.R. Ahmed, Z. Amiri, M. Anderson, A.J. Austermann, J.E. Avva, J.S. Barkats, D. Thakur, R. Basu Beall, J.A. Bender, A.N. Benson, B.A. Bianchini, F. Bischoff, C.A. Bleem, L.E. Bock, J.J. Boenish, H. Bullock, E. Buza, V. Carlstrom, J.E. Chang, C.L. Cheshire, J.R. Chiang, H.C. Chou, T.-L. Citron, R. Connors, J. Moran, C. Corbett Cornelison, J. Crawford, T.M. Crites, A.T. Crumrine, M. Cukierman, A. de Haan, T. Dierickx, M. Dobbs, M.A. Duband, L. Everett, W. Fatigoni, S. Filippini, J.P. Fliescher, S. Gallicchio, J. George, E.M. Germaine, T.St. Goeckner-Wald, N. Goldfinger, D.C. Grayson, J. Gupta, N. Hall, G. Halpern, M. Halverson, N.W. Harrison, S. Henderson, S. Henning, J.W. Hildebrandt, S.R. Hilton, G.C. Holder, G.P. Holzapfel, W.L. Hrubes, J.D. Huang, N. Hubmayr, J. Hui, H. Irwin, K.D. Kang, J. Karkare, K.S. Karpel, E. Kefeli, S. Kernasovskiy, S.A. Knox, L. Kovac, J.M. Kuo, C.L. Lau, K. Lee, A.T. Leitch, E.M. Li, D. Lowitz, A. Manzotti, A. McMahon, J.J. Megerian, K.G. Meyer, S.S. Millea, M. Mocanu, L.M. Moncelsi, L. Montgomery, J. Nadolski, A. Namikawa, T. Natoli, T. Netterfield, C.B. Nguyen, H.T. Nibarger, J.P. Noble, G. Novosad, V. O’Brient, R. Ogburn, R.W. Omori, Y. Padin, S. Palladino, S. Patil, S. Prouve, T. Pryke, C. Racine, B. Reichardt, C.L. Reintsema, C.D. Richter, S. Ruhl, J.E. Saliwanchik, B.R. Schaffer, K.K. Schillaci, A. Schmitt, B.L. Schwarz, R. Sheehy, C.D. Sievers, C. Smecher, G. Soliman, A. Stark, A.A. Steinbach, B. Sudiwala, R.V. Teply, G.P. Thompson, K.L. Tolan, J.E. Tucker, C. Turner, A.D. Umiltà, C. Veach, T. Vieira, J.D. Vieregg, A.G. Wandui, A. Wang, G. Weber, A.C. Whitehorn, N. Wiebe, D.V. Willmert, J. Wong, C.L. Wu, W.L. Kimmy Yang, H. Yefremenko, V. Yoon, K.W. Young, E. Yu, C. Zeng, L. Zhang, C. Cardiff University CardiffCF10 3XQ United Kingdom SLAC National Accelerator Laboratory 2575 Sand Hill Road Menlo ParkCA94025 United States Kavli Institute for Particle Astrophysics and Cosmology Stanford University 452 Lomita Mall StanfordCA94305 United States Department of Physics and Astronomy University of British Columbia VancouverBCV6T 1Z1 Canada Fermi National Accelerator Laboratory MS209 P.O. Box 500 BataviaIL60510 United States NIST Quantum Devices Group 325 Broadway Mailcode 817.03 BoulderCO80305 United States Department of Physics University of Colorado BoulderCO80309 United States Department of Physics University of California BerkeleyCA94720 United States Harvard-Smithsonian Center for Astrophysics 60 Garden Street CambridgeMA02138 United States California Institute of Technology MS 249-17 1216 E. California Blvd. PasadenaCA91125 United States High Energy Physics Division Argonne National Laboratory 9700 S. Cass Avenue ArgonneIL60439 United States Kavli Institute for Cosmological Physics University of Chicago 5640 South Ellis Avenue ChicagoIL60637 United States Department of Astronomy and Astrophysics University of Chicago 5640 South Ellis Avenue ChicagoIL60637 United States School of Physics University of Melbourne ParkvilleVIC3010 Australia Department of Physics University of Cincinnati CincinnatiOH45221 United States Jet Propulsion Laboratory PasadenaCA91109 United States Department of Physics Harvard University CambridgeMA02138 United States Minnesota Institute for Astrophysics University of Minnesota MinneapolisMN55455 United States Department of Physics University of Chicago 5640 South Ellis Avenue ChicagoIL60637 United States Enrico Fermi Institute University of Chicago 5640 South Ellis Avenue ChicagoIL60637 United States Department of Physics McGill University 3600 Rue University MontrealQCH3A 2T8 Canada School of Mathematics Statistics & Computer Science University of KwaZulu-Natal

We present a constraint on the tensor-to-scalar ratio, r, derived from measurements of cosmic microwave background (CMB) polarization B-modes with "delensing," whereby the uncertainty on r contributed by the sample variance of the gravitational lensing B-modes is reduced by cross-correlating against a lensing B-mode template. This template is constructed by combining an estimate of the polarized CMB with a tracer of the projected large-scale structure. The large-scale-structure tracer used is a map of the cosmic infrared background derived from Planck satellite data, while the polarized CMB map comes from a combination of South Pole Telescope, Bicep/Keck, and Planck data. We expand the Bicep/Keck likelihood analysis framework to accept a lensing template and apply it to the Bicep/Keck data set collected through 2014 using the same parametric foreground modelling as in the previous analysis. From simulations, we find that the uncertainty on r is reduced by ∼ 10%, from σ(r)= 0.024 to 0.022, which can be compared with a ∼ 26% reduction obtained when using a perfect lensing template or if there were zero lensing B-modes. Applying the technique to the real data, the constraint on r is improved from r0.05 Copyright © 2020, The Authors. All rights reserved.

关键词： Cosmology

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computational study of electronic properties of carbazole derivatives compounds as sensitizer on dye-sensitized solar cells (DSSC)

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AIP Conference Proceedings 2018年第1期2049卷

作者： Annisa T. Apriliani Yuly Kusumawati Athar L. Ivansyah Muhamad A. Martoprawiro 1Chemistry Department Faculty of Natural Sciences Institut Teknologi Sepuluh Nopember (ITS) ITS Campus Sukolilo Surabaya East Java 60111 Indonesia 2Master Program in Computational Science Faculty of Mathematics and Natural Science Institut Teknologi Bandung (ITB) Jl. Ganesha 10 Bandung West Java 401232 Indonesia 3Department Chemistry Faculty of Mathematics and Natural Science Institut Teknologi Bandung Jl. Ganesha 10 Bandung West Java 401232 Indonesia

The effect of the addition electron donating moiety –OCH3, -NHCH3, -OC5H11 and –NH(C5H11) to the electronic properties of carbazole dye, CT2 have been studied using DFT and TDDFT method at CAM-B3LYP level theory and 6-31G* basis set. The optimized structure were obtained from DFT calculation, whilst electronic properties were obtained using single point TDDFT calculation. The calculated electronic properties were HOMO-LUMO energy level, UV-Vis absorption spectrum, charge transfer quantity and chare transfer distance at ground state and excitation state. The result reveal that the addition of long alkyl electron donating moiety –NH(C5H11) or CT_NC5, give the best result. Contribution HOMO-to-LUMO transition in CT_NC5 molecule of 77%, the quantify charge transfer (qCT) of 1,004 and LUMO energy (ELUMO = of-1,810 eV). Overall, CT_NC5 gave the best result and promising to be applied as a sensitizer in Dye Sensitized Solar Cell (DSSC).

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Wide nutation: binary black-hole spins repeatedly oscillating from full alignment to full anti-alignment

arXiv

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arXiv 2018年

作者： Gerosa, Davide Lima, Alicia Berti, Emanuele Sperhake, Ulrich Kesden, Michael O’Shaughnessy, Richard TAPIR 350-17 California Institute of Technology 1200 E California Boulevard PasadenaCA91125 United States School of Physics and Astronomy Institute for Gravitational Wave Astronomy University of Birmingham BirminghamB15 2TT United Kingdom Department of Physics and Astronomy Bowdoin College BrunswickME04011 United States Department of Physics and Astronomy Johns Hopkins University 3400 N. Charles Street BaltimoreMD21218 United States Department of Physics and Astronomy University of Mississippi UniversityMS38677 United States Department of Applied Mathematics and Theoretical Physics Centre forMathematical Sciences University of Cambridge Wilberforce Road CambridgeCB3 0WA United Kingdom Department of Physics University of Texas at Dallas RichardsonTX75080 United States Center for Computational Relativity and Gravitation Rochester Institute of Technology 85 Lomb Memorial Drive RochesterNY14623 United States

Within the framework of 2PN black-hole binary spin precession, we explore configurations where one of the two spins oscillates from being completely aligned with the orbital angular momentum to being completely anti-aligned with it during a single precession cycle. This wide nutation is the extreme limit of the generic phenomenon of spin nutation in black-hole binaries. Crucially, wide nutation happens on the short precession time scale and it is not a secular effect due to gravitational-wave radiation reaction. The spins of these binaries, therefore, flip repeatedly as one of these special configurations is entered. Binaries with total mass M, mass ratio q, and dimensionless spin χ1 (χ2) of the more (less) massive black hole are allowed to undergo wide nutation at binary separations r ≤ rwide ≡ [(qχ2 − χ1)/(1 − q)]2M. Sources that are more likely to nutate widely have similar masses and effective spins close to zero. Copyright © 2018, The Authors. All rights reserved.

关键词： Gravity waves

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