Vesi ja vähähiilinen talous

Tiivistelmä. Tässä kandidaatintyössä tarkastellaan vesi ja vähähiilistä taloutta. Aihe on todella laaja, joten sitä on hieman rajattu. Työssä käydään läpi mitä vesi ja vähähiilinen talous tarkoittavat, miten vähähiiliseen talouteen päästään ja kuinka vesi liittyy tähän. Lyhyesti myös esitetään, mitä ovat uusiutuvat energiamuodot ja kuinka niitä tuotetaan Suomessa ja kansainvälisellä tasolla. Vuonna 2018 Suomessa tuotettiin uusiutuvilla energiamuodoilla sähköä 47 % kokonaissähköntuotannosta, pääosin vesi- ja tuulivoimalla. Työssä myös perehdytään Pariisin ilmastosopimukseen, koska se on yksi tärkeimmistä suunnan näyttäjistä kohti vähähiilistä taloutta. Työ on toteutettu kirjallisuusselvityksenä. Sekä vähän vettä kuluttava, että vähähiilinen talous edellyttävät oikeanlaisten energiamuotojen valitsemista. Molempia talouksia tukevia energiamuotoja ovat ydinvoima, aurinkovoima ja tuulivoima. Näissä kolmessa energiamuodossa on suhteessa tuotettuun energiamäärään pienet kasvihuonepäästöt, mutta myös pieni veden tarveWater and low carbon economy. Abstract. The topic of this thesis is water and low-carbon economy. This topic is extensive, so it has been restricted. This thesis focuses on what water and low-carbon economy mean, how to reach low-carbon economy and how water can be associated with this. This thesis also displays what renewable energy sources are and how they are generated in Finland and internationally. In 2018 Finland generated 47 percent of its total electricity production by renewable energy sources, mainly by hydropower and wind power. This thesis also discusses the Paris Climate Agreement, since it is one of the main predecessors towards low carbon economy. This thesis has been carried out as a literature review. The choice of energy sources is essential for reaching an economy that uses little water and carbon. Energy sources that maintain both economies are nuclear power, solar power, and wind power. These three sources of energy have low greenhouse gas emissions in contrast to the amount of energy produced, but also have low water demand

Työnaikaisten siltojen aukkomitoitus

Tiivistelmä. Tämän työn tavoitteena on tehdä selvitys työnaikaisten siltojen aukkomitoituksesta kirjallisuuskatsauksen ja kyselytutkimuksen avulla. Työssä perehdytään Suomessa käytettävään varasiltakalustoon, jota käytetään yleensä väliaikaisena siltana varsinaisen sillan rakentamisen tai sen korjauksen aikana, tilapäisratkaisujen rakenteisiin sekä luonnossa tapahtuviin erikoistilanteisiin, kuten jääpatoihin sekä hyydetulviin. Työn keskivaiheilla avataan aukkomitoituksen periaatteet, ongelmat sekä yleisimmät mitoitusmenetelmät. Työn lopussa esitetään johtopäätökset ja suositukset tulevaa tutkimusta varten. Työnaikaisen sillan aukkomitoituksen määrittelyyn vaikuttaa monia eri tekijöitä. Näitä ovat ympäristötekijät, rakenteelliset ratkaisut sekä ilmastonmuutoksen aiheuttamat ääriolosuhteet. Ympäristötekijät sisältävät vesistön luonteen, kuten alttiuden tulville, mutta myös suppojään esiintymisen. Rakenteelliset ratkaisut ja päätökset vaikuttavat rakentamisen aikana, esimerkiksi kuinka tukirakenteet ja siltaosat suunnataan kohti pysyvää siltaa. Ilmaston lämpeneminen aiheuttaa ääriolosuhteita, jotka johtavat muutoksiin rankkasateiden ja kuivien jaksojen esiintymiseen. Sähköpostikysely työtä varten tehtiin lokakuussa 2022. Sähköposti lähetettiin yhteensä seitsemälle henkilölle, jotka työskentelevät työnaikaisten siltojen parissa, joko suunnittelijoina tai rakennuttajina. Monet vastanneista vastasivat kollegoiden kanssa yhdessä, jolloin vastauksia tuli lopulta yhdeksältä henkilöltä. Kyselyn avulla kartoitettiin työnaikaisen sillan suunnittelun ja rakentamisen ongelmakohdat sekä tarve mahdolliselle ohjeistukselle. Kyselyn tulosten analyysimenetelmänä toimi sisällönanalyysi. Kyselyn perusteella valtaosa henkilöistä on tietoisia tärkeimmistä tekijöistä ja ongelmakohdista työnaikaisten siltojen suunnittelussa hydrologian ja hydraulisen puolen näkökulmista. Samalla selvisi, että työnaikaisen sillan aukkomitoitukseen ei ole Suomessa riittävää ohjeistusta tai opasta. Ohjeistuksen uupuessa lähtötietoja ja menetelmiä joudutaan arvaamaan ja soveltamaan, jolloin aukkomitoituksessa virheen mahdollisuus on suuri.Gap sizing of temporary bridges. Abstract. The aim of this work is to investigate the gap sizing of temporary bridges through a literature review and a questionnaire survey. The work examines the emergency bridge equipment used in Finland. Emergency bridges are usually used as temporary solutions during the construction or mending of the main permanent bridge. They are also used as temporary structures, and during some special natural phenomena, e.g., ice jams and slush floods. In the middle section of the work the principles, problems and most common sizing methods of gap sizing are explained. Conclusions and recommendations for future research are presented at the end of the work. There is a plethora of factors that affect the gap sizing of bridges. These include environmental factors, structural decisions, and extreme weather conditions caused by climate change. Environmental factors include the nature of the body of water such as its susceptibility to flooding, and the occurrence of frazil ice. Structural decisions and solutions have an impact during construction, an example being how the supports and bridge span are directed to the permanent bridge. Global warming causes extreme weather conditions, which result in changes in the occurrence of heavy rain and droughts. An e-mail questionnaire for the work was conducted in October 2022. The e-mail was sent to a total of seven people, who work with temporary bridges as either designers or contractors. Many of the respondents wrote their responses with their colleagues, which meant that in total nine people responded. The questionnaire was used to define the problem areas in the design and construction of temporary bridges, as well as the need for possible guidelines. Content analysis was used as the analysis method for the results of the questionnaire. Based on the questionnaire, the majority of people are aware of the major factors and problem areas in designing temporary bridges, from the hydrologic and hydraulic perspectives. At the same time, it was found that the gap sizing of temporary bridges does not have adequate guidelines or instructions in Finland. In the absence of an overall guide, the initial information must be guessed, and methods adapted. This causes a major chance of error in gap sizin

Modeling optical constants from the absorption of organic thin films using a modified Lorentz oscillator model

Optical constants of organic thin films can be evaluated using the Lorentz oscillator model (LOM) which fails to fit inhomogeneously broadened absorption of highly concentrated molecular films. In modified LOM (MLOM), the inhomogeneous broadening is implemented through a frequency-dependent adjustable broadening function. In this work, we evaluate the optical constants of rhodamine 6G doped poly-vinyl alcohol thin films with varying doping concentration (including also extensively high concentrations) using MLOM, which outperforms LOM by showing a better agreement with the experimental results. Our proposed method provides a way to accurately determine optical constants of isotropic organic thin films only from their absorption spectra without spectroscopic ellipsometry.Peer reviewe

Modeling optical constants from the absorption of organic thin films using a modified Lorentz oscillator model

Optical constants of organic thin films can be evaluated using the Lorentz oscillator model (LOM) which fails to fit inhomogeneously broadened absorption of highly concentrated molecular films. In modified LOM (MLOM), the inhomogeneous broadening is implemented through a frequency-dependent adjustable broadening function. In this work, we evaluate the optical constants of rhodamine 6G doped poly-vinyl alcohol thin films with varying doping concentration (including also extensively high concentrations) using MLOM, which outperforms LOM by showing a better agreement with the experimental results. Our proposed method provides a way to accurately determine optical constants of isotropic organic thin films only from their absorption spectra without spectroscopic ellipsometry

Lipoprotein subclass metabolism in nonalcoholic steatohepatitis

Peer reviewe

Optimizing geometry of low-Q all-metal Fabry-Pérot microcavity for fluorescence spectroscopy

Fluorescence spectroscopy is commonly employed to study the excited-state photophysics of organic molecules. Planar Fabry-Pérot microcavities play an essential role in such studies and a strategic cavity design is necessary to attain an enhanced light-matter interaction. In this work, we computationally study different geometries for a planar metallic Fabry-Pérot microcavity tuned for the absorption of Sulforhodamine 101, a typical dye for fluorescence spectroscopy. The cavity consists of a polymer layer enclosed between two silver mirrors, where the thicknesses of all the three layers are varied to optimize the cavity. Our transfer-matrix and finite-difference time-domain simulations suggest that a cavity with 30 nm thin top mirror and 200 nm fully reflective thick bottom mirror, thus having only reflection and absorption and no transmission, is an optimal design for maximizing the Purcell factor and spectral overlap between the cavity and molecule, while still sustaining an efficient measurability of the fluorescence.peerReviewe

Numerical study on the limit of quasi-static approximation for plasmonic nanosphere

Plasmonic nanospheres are often employed as resonant substrates in many nanophotonic applications, like in enhanced spectroscopy, near-field microscopy, photovoltaics, and sensing. Accurate calculation and tuning of optical responses of such nanospheres are essential to achieve optimal performance. Mie theory is widely used to calculate optical properties of spherical particles. Although, an approximated version of Mie approach, the quasi-static approximation (QSA) can also be used to determine the very same properties of those spheres with a lot simpler formulations. In this work, we report our numerical study on the limit and accuracy of QSA with respect to the rigorous Mie approach. We calculated scattering, absorption and extinction spectra of silver and gold nanospheres in air with varying sizes using both QSA and Mie theory. Then, we extracted spectral positions of the resonance peaks from their calculated optical responses and defined the error present in QSA as the difference between the spectral positions of the resonance peaks calculated by QSA and Mie method. Our error analysis reveals that QSA approach yields nonlinear increment in error with linear increment in size of the nanosphere and that the amount of error is significantly less in the case of gold spheres compared to the silver ones. We also provide a polynomial-fitted error function that resembles the qualitative trend in error

Effect of molecular Stokes shift on polariton dynamics

When the enhanced electromagnetic field of a confined light mode interacts with photoactive molecules, the system can be driven into the regime of strong coupling, where new hybrid light–matter states, polaritons, are formed. Polaritons, manifested by the Rabi split in the dispersion, have shown potential for controlling the chemistry of the coupled molecules. Here, we show by angle-resolved steady-state experiments accompanied by multi-scale molecular dynamics simulations that the molecular Stokes shift plays a significant role in the relaxation of polaritons formed by organic molecules embedded in a polymer matrix within metallic Fabry–Pérot cavities. Our results suggest that in the case of Rhodamine 6G, a dye with a significant Stokes shift, excitation of the upper polariton leads to a rapid localization of the energy into the fluorescing state of one of the molecules, from where the energy scatters into the lower polariton (radiative pumping), which then emits. In contrast, for excitonic J-aggregates with a negligible Stokes shift, the fluorescing state does not provide an efficient relaxation gateway. Instead, the relaxation is mediated by exchanging energy quanta matching the energy gap between the dark states and lower polariton into vibrational modes (vibrationally assisted scattering). To understand better how the fluorescing state of a molecule that is not strongly coupled to the cavity can transfer its excitation energy to the lower polariton in the radiative pumping mechanism, we performed multi-scale molecular dynamics simulations. The results of these simulations suggest that non-adiabatic couplings between uncoupled molecules and the polaritons are the driving force for this energy transfer process.peerReviewe

Thermal disorder prevents the suppression of ultra-fast photochemistry in the strong light-matter coupling regime

Abstract Strong coupling between molecules and confined light modes of optical cavities to form polaritons can alter photochemistry, but the origin of this effect remains largely unknown. While theoretical models suggest a suppression of photochemistry due to the formation of new polaritonic potential energy surfaces, many of these models do not account for the energetic disorder among the molecules, which is unavoidable at ambient conditions. Here, we combine simulations and experiments to show that for an ultra-fast photochemical reaction such thermal disorder prevents the modification of the potential energy surface and that suppression is due to radiative decay of the lossy cavity modes. We also show that the excitation spectrum under strong coupling is a product of the excitation spectrum of the bare molecules and the absorption spectrum of the molecule-cavity system, suggesting that polaritons can act as gateways for channeling an excitation into a molecule, which then reacts normally. Our results therefore imply that strong coupling provides a means to tune the action spectrum of a molecule, rather than to change the reaction