The use of direct current produced by photovoltaic systems in LED lighting systems of office buildings

Toimistorakennuksiin integroidut aurinkosähköjärjestelmät tulevat lisääntymään tulevaisuudessa. Ne vähentävät rakennuksien tarvitsemaa verkkosähköä, parantavat yritysten imagoa ja niillä voidaan korvata muita rakennusmateriaaleja. Myös Suomessa pystytään tuottamaan aurinkosähköä. Järjestelmän tuottama tasasähkö muutetaan yleensä vaihtosuuntaajissa yleiseen verkkoon soveltuvaksi vaihtosähköksi. Tämä aiheuttaa tehohäviöitä tuotetulle aurinkosähkölle ja lisäksi aurinkosähkölle suunnitellut vaihtosuuntaajat kasvattavat entisestään järjestelmän investointikustannuksia. Tässä työssä selvitettiin mahdollisuutta käyttää tuotettua tasasähköä LED-valaistusjärjestelmissä ja siitä koituvia hyötyjä. LEDit käyttävät tasasähköä ja vaihtosähköverkkoon kytkettäessä ne tarvitsevat liitäntälaitteen, joka muuttaa vaihtosähkön tasasähköksi. Tasasähkön käyttäminen toimistorakennuksessa vaatisi erillisen tasasähköverkon toteuttamisen vaihtosähköverkon rinnalle. Työssä tehtiin suunnitelmat tasasähköverkkoon kytketystä aurinkosähköjärjestelmästä, tasasähköverkosta ja LED-valaistuksesta Vantaalle suunnitteilla olevaan toimistorakennukseen Avia Toweriin. Suunnitelmien avulla tehtiin elinkaarikustannuslaskelmat järjestelmän eri osille. Avia Toweriin tullaan todennäköisesti integroimaan aurinkosähköjärjestelmä. Tasasähköverkon ja LED-valaistusjärjestelmän suunnitelmat eivät tule toteutumaan, vaan ne tehtiin varta vasten tätä diplomityötä varten.The amount of building integrated photovoltaic systems in office buildings will increase in the future. They reduce the need of electricity from the network, they improve the image of the corporate and they can replace other building materials. Even in Finland it is possible to produce solar electricity. The direct current produced by PV systems is usually inverted to alternate current compatible to the electricity network. This process causes power losses and the power inverters increase the investment costs of the system. In this work the possibility to use the produced DC in office LED lighting systems is examined. LEDs use direct current and to connect LED luminaire to the public network a ballast is needed to convert the alternate current to direct current. The use of direct current in the office buildings would require a separate DC-network in addition to the AC-network. In this work plans were made to the DC-network-connected PV-system, to the DC-network and to the LED lighting system. The plans were applied to Avia Tower office building, which is planned to be built in Vantaa. With the plans the life cycle cost calculations were made for all the different parts of the system. A photovoltaic system will be probably integrated to the office building Avia Tower. The DC-network and the LED lighting system will be not realized in the building. The plans were made specifically for the purpose of this thesis

Analysing Errors of Open Information Extraction Systems

We report results on benchmarking Open Information Extraction (OIE) systems using RelVis, a toolkit for benchmarking Open Information Extraction systems. Our comprehensive benchmark contains three data sets from the news domain and one data set from Wikipedia with overall 4522 labeled sentences and 11243 binary or n-ary OIE relations. In our analysis on these data sets we compared the performance of four popular OIE systems, ClausIE, OpenIE 4.2, Stanford OpenIE and PredPatt. In addition, we evaluated the impact of five common error classes on a subset of 749 n-ary tuples. From our deep analysis we unreveal important research directions for a next generation of OIE systems.Comment: Accepted at Building Linguistically Generalizable NLP Systems at EMNLP 201

Can the Steep Mass Profile of A1689 Be Explained by a Triaxial Dark Halo?

The steep mass profile of A1689 derived from recent detailed lensing observations is not readily reconciled with the low concentration halos predicted by the standard CDM model. However, halo triaxiality may act to bias the profile constraints derived assuming a spherically symmetric mass distribution, since lensing relates only to the projected mass distribution. A degree of halo triaxiality is inherent to the CDM structure formation, arising from the collision-less nature of the dark matter. Here we compare the CDM-based model predictions of triaxial halo with the precise lensing measurements of A1689 based on the ACS/HST and Subaru data, over a wide range of 10kpc<r<2Mpc. The model lensing profiles cover the intrinsic spread of halo mass and shape, and are projected over all inclinations when comparing with the data. We show that the model parameters are only weakly constrained and strongly degenerate mainly because of the lack of information along the line of sight. In particular, the limits on the concentration parameter become less restrictive with increasing triaxiality. Yet, by comparing the obtained constraints with expected probability distributions for the axis ratio and concentration parameters computed from numerical simulations, we find that ~6% of cluster-size halos in the CDM model can match the A1689 lensing observations at the 2-sigma level, corresponding to cases where the major-axis of the halo is aligned with the line of sight. Thus halo triaxiality could reduce the apparent discrepancy between theory and observation. This hypothesis needs to be further explored by a statistical lensing study for other clusters as well as by complementary three-dimensional information derived using X-ray, kinematics, and SZ effect observations.Comment: 7 pages, 6 figures, accepted for publication in Ap

Probing the Cluster Mass Distribution using Subaru Weak Lensing Data

We present results from a weak lensing analysis of the galaxy cluster A1689 (z=0.183) based on deep wide-field imaging data taken with Suprime-Cam on Subaru telescope. A maximum entropy method has been used to reconstruct directly the projected mass distribution of A1689 from combined lensing distortion and magnification measurements of red background galaxies.The resulting mass distribution is clearly concentrated around the cD galaxy, and mass and light in the cluster are similarly distributed in terms of shape and orientation. The azimuthally-averaged mass profile from the two-dimensional reconstruction is in good agreement with the earlier results from the Subaru one-dimensional analysis of the weak lensing data, supporting the assumption of quasi-circular symmetry in the projected mass distribution of the cluster.Comment: To appear in Mod. Phys. Lett. A, 8pages, 5 figures, minor typo errors corrected, Fig.5 modifie

A proof of validity for multiphase Whitham modulation theory

It is proved that approximations which are obtained as solutions of the multiphase Whitham modulation equations stay close to solutions of the original equation on a natural time scale. The class of nonlinear wave equations chosen for the starting point is coupled nonlinear Schr\"odinger equations. These equations are not in general integrable, but they have an explicit family of multiphase wavetrains that generate multiphase Whitham equations which may be elliptic,hyperbolic, or of mixed type. Due to the change of type, the function space setup is based on Gevrey spaces with initial data analytic in a strip in the complex plane. In these spaces a Cauchy- Kowalevskaya-like existence and uniqueness theorem is proved. Building on this theorem and higher-order approximations to Whitham theory, a rigorous comparison of solutions, of the coupled nonlinear Schr\"odinger equations and the multiphase Whitham modulation equations, is obtained.Comment: 21 pages, no figure

Detecting the Gravitational Redshift of Cluster Gas

We examine the gravitational redshift of radiation emitted from within the potential of a cluster. Spectral lines from the intracluster medium (ICM) are redshifted in proportion to the emission-weighted mean potential along the line of sight, amounting to approximately 50 km/s at a radius of 100 kpc/h, for a cluster dispersion of 1200 km/s. We show that the relative redshifts of different ionization states of metals in the ICM provide a unique probe of the three-dimensional matter distribution. An examination of the reported peculiar velocities of cD galaxies in well studied Abell clusters reveals they are typically redshifted by an average of $\sim +200$ km/s. This can be achieved by gravity with the addition of a steep central potential associated with the cD galaxy. Note that in general gravitational redshifts cause a small overestimate of the recessional velocities of clusters by an average of $\sim$ 20 km/s.Comment: 6 pages, 3 figures, accepted to the Astrophysical Journal Letter

Herstellung von GaN-Schichten mittels Hochtemperatur-Gasphasenepitaxie

Verbindungshalbleiter mit einer großen Bandlücke wie Galliumnitrid (GaN) sind aufgrund ihrer hervorragenden elektronischen Eigenschaften für die Halbleiterindustrie von großem Interesse. Die Hochtemperatur-Gasphasenepitaxie, die auf dem physikalischen Gasphasentransport von Gallium basiert, ist eine alternative Methode der Gasphasenepitaxie von GaN. Im Mittelpunkt der vorliegenden Arbeit standen die Weiterentwicklung der Methode hinsichtlich der Verringerung der Kontamination und die Reduzierung der Versetzungsdichte in den GaN-Schichten. Dazu wurde eine neue Verdampfungszelle entwickelt und die komplexen, mehrstufigen Nukleations- und Wachstumsprozesse systematisch untersucht. Insgesamt wurden zu kommerziell verfügbaren GaN-Schichten vergleichbare Defektdichten erreicht. Zusätzlich wurde die Methode zur Abscheidung auf Saphir-Substraten mit einem Durchmesser von bis zu 2 Zoll aufskaliert

Overview of phase-field models for fatigue fracture in a unified framework

In the last ten years, the phase-field method has gained much attention as a novel method to simulate fracture due to its straightforward way allowing to cover crack initiation and propagation without additional conditions. More recently, it has also been applied to fatigue fracture due to cyclic loading. This publication gives an overview of the main phase-field fatigue models published to date. We present all models in a unified variational framework for best comparability. Subsequently, the models are compared regarding their most important features. It becomes apparent that they can be classified in mainly two categories according to the way fatigue is implemented in the model - that is as a gradual degradation of the fracture toughness or with an additional term in the crack driving force. We aim to provide a helpful guide for choosing the appropriate model for different applications and for developing existing models further