FEM-laskentaohjelman aikahistoria-analyysin hyödyntäminen korkeiden rakennusten tuulikuorman aiheuttaman värähtelyn mitoituksessa

Tiivistelmä. Korkea rakentaminen tuottaa haasteita rakennesuunnittelussa, joista yksi on tuulikuorman aiheuttama värähtely. Eurokoodimitoitus antaa tavan mitoittaa geometrialtaan varsin yksinkertaisia rakennuksia, minkä takia todellisuudessa Eurokoodimitoitus ei monesti sovellu värähtelytarkasteluun. Työssä selvitetään värähtelyn aiheuttamia vasteita FEM-ohjelman avulla, sekä selvitetään sen soveltuvuus ja hyödyllisyys vasteiden mitoituksessa. Työssä tutkitaan ICON Suurpeltoon suunniteltua 21-kerroksisen rakennuksen käyttäytymistä tuulikuormituksessa. Työssä selvitetään Eurokoodin antaman menetelmän soveltamista kohteeseen, sekä tehdään FEM-ohjelmalla aikahistoria-analyysi. Työssä esitettyjen tulosten perusteella voidaan sanoa, että Eurokoodi mitoitus soveltuu lähinnä matalien ja keskikorkeiden rakennusten mitoitukseen tai vertailutuloksiksi. Varsinkin tuulen poikkisuuntaisen värähtelyn aiheuttamien kiihtyvyyksien arviointi on epävarmaa Eurokoodin mukaisin menetelmin. Mitoitus FEM-ohjelmalla antaa lupaavia tuloksia, ilman että rakennukselle olisi asetettava rajoituksia geometrian tai lineaarisuuden suhteen. Menetelmän yksi suurimmista hyödyistä on se, että sillä voidaan myös selvittää vääntövärähtelyn vasteet. Menetelmä on kuitenkin altis käyttäjän virheille ja sen tarkkuutta olisi syytä tutkia tarkemmin tuulitunnelitestauksen avulla.Utilizing FEM-programs time history analysis during wind caused vibrations in high-rise buildings. Abstract. There are many difficulties in designing high-rise buildings, and one of those is taking account the vibration caused by wind loads. Eurocode provides a method to calculate the vibration responses of the building, but it only covers very basic building shapes and therefore isn’t suitable at all cases. In this thesis, vibration responses are calculated by FEM-program and it is explored if those results can be used in designing process. In this thesis, an example case of ICON Suurpelto, a 21-storey building, is used to study how wind loads affect the building. For this case, Eurocode method is carried along with time history analysis of FEM-program, and the results are cross examined. The results of this thesis imply that Eurocode method should only be used to calculate the vibration responses of low and mid-high buildings or used as a supplement result. Especially the across wind acceleration results are questionable with the method. The calculations results obtained from FEM-program are in line with the results provided by Eurocode methods, but with more freedom regarding the shape and linearity of the building. Unlike the method in Eurocode, it also provides a way to calculate torsional acceleration responses. Calculating the response results with FEM-program however is sensitive to user errors and the accuracy of the results is hard to estimate without wind tunnel experiments

What Happens Next? Event Prediction Using a Compositional Neural Network Model

We address the problem of automatically acquiring knowledge of event sequences from text, with the aim of providing a predictive model for use in narrative generation systems. We present a neural network model that simultaneously learns embeddings for words describing events, a function to compose the embeddings into a representation of the event, and a coherence function to predict the strength of association between two events. We introduce a new development of the narrative cloze evaluation task, better suited to a setting where rich information about events is available. We compare models that learn vector-space representations of the events denoted by verbs in chains centering on a single protagonist. We find that recent work on learning vector-space embeddings to capture word meaning can be effectively applied to this task, including simple incorporation of a verb's arguments in the representation by vector addition. These representations provide a good initialization for learning the richer, compositional model of events with a neural network, vastly outperforming a number of baselines and competitive alternatives

High-energy magnetic excitations in overdoped La2−x_{2-x}Srx_{x}CuO4_{4} studied by neutron and resonant inelastic X-ray scattering

We have performed neutron inelastic scattering and resonant inelastic X-ray scattering (RIXS) at the Cu-$L_3$ edge to study high-energy magnetic excitations at energy transfers of more than 100 meV for overdoped La$_{2-x}$Sr$_{x}$CuO$_{4}$ with $x=0.25$ ($T_c=15$ K) and $x=0.30$ (non-superconducting) using identical single crystal samples for the two techniques. From constant-energy slices of neutron scattering cross-sections, we have identified magnetic excitations up to ~250 meV for $x=0.25$. Although the width in the momentum direction is large, the peak positions along the (pi, pi) direction agree with the dispersion relation of the spin-wave in the non-doped La$_{2}$CuO$_{4}$ (LCO), which is consistent with the previous RIXS results of cuprate superconductors. Using RIXS at the Cu-$L_3$ edge, we have measured the dispersion relations of the so-called paramagnon mode along both (pi, pi) and (pi, 0) directions. Although in both directions the neutron and RIXS data connect with each other and the paramagnon along (pi, 0) agrees well with the LCO spin-wave dispersion, the paramagnon in the (pi, pi) direction probed by RIXS appears to be less dispersive and the excitation energy is lower than the spin-wave of LCO near (pi/2, pi/2). Thus, our results indicate consistency between neutron inelastic scattering and RIXS, and elucidate the entire magnetic excitation in the (pi, pi) direction by the complementary use of two probes. The polarization dependence of the RIXS profiles indicates that appreciable charge excitations exist in the same energy range of magnetic excitations, reflecting the itinerant character of the overdoped sample. A possible anisotropy in the charge excitation intensity might explain the apparent differences in the paramagnon dispersion in the (pi, pi) direction as detected by the X-ray scattering.Comment: 7 pages, 7 figure

Quantum spin correlations in an organometallic alternating sign chain

High resolution inelastic neutron scattering is used to study excitations in the organometallic magnet DMACuCl$_3$. The correct magnetic Hamiltonian describing this material has been debated for many years. Combined with high field bulk magnetization and susceptibility studies, the new results imply that DMACuCl$_3$ is a realization of the $S=1/2$ alternating antiferromagnetic-ferromagnetic (AFM-FM) chain. Coupled-cluster calculations are used to derive exchange parameters, showing that the AFM and FM interactions have nearly the same strength. Analysis of the scattering intensities shows clear evidence for inter-dimer spin correlations, in contrast to existing results for conventional alternating chains. The results are discussed in the context of recent ideas concerning quantum entanglement.Comment: 5 pages, 4 figures included in text. Submitted to APS Journal

Micron-Sized Particles Detected in the Vicinity of Jupiter by the Voyager Plasma Wave Instruments

Wideband waveform data obtained by the plasma wave instruments onboard the Voyager 1 and 2 spacecraft have been used to study micron-sized dust particles in the vicinity of Jupiter. The technique used was developed during the flybys of Saturn, Uranus, and Neptune, and makes use of the fact that a particle striking the spacecraft at 10-20 km/s causes a voltage pulse in the plasma wave receiver. The waveform of the voltage pulse is much different than the waveform of plasma waves and provides a highly reliable method of detecting micron-sized dust particles. Although the dust impact rate observed in the vicinity of Jupiter is much lower than the rates at Saturn, Uranus, and Neptune, the particles are easily detectable. Approximately 1200 48-second frames of wideband waveform data were examined in the vicinity of Jupiter. Dust impact signatures were found in approximately 20% of these frames. The peak impact rates are about 1 impact per second, and the peak number densities are about 10(exp -5) m(exp -3). Most of the impacts occurred near the equatorial plane at radial distances less than about 35 R(sub j) from Jupiter. Analysis of the detection threshold indicates that the particles have masses greater than 10(exp -11) g, which corresponds to particles with diameters of a few micrometers or larger