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The CITIUS light source
Sandra Gardonio, Giovanni De Ninno, Barbara Ressel, 2013, published scientific conference contribution abstract

Found in: ključnih besedah
Keywords: femtosecond laser source, time resolved photoemission spectroscopy, correlated electron materials
Published: 06.05.2014; Views: 3408; Downloads: 15
URL Fulltext (0,00 KB)

Chemical and structural investigation of the cobalt phthalocyanine
Matija Stupar, 2015, master's thesis

Abstract: In the last two decades, studies on organic molecules mimicking substances of fundamental importance in nature, like chlorophyll or hemoglobin, have attracted researchers’ attention. These molecules are building blocks for a family of materials also referred to as “organic semiconductors”. Such compounds can be implemented in numerous applications, ranging from data-storage to light harvesting. Some of their fundamental advantages include low cost, light weight, relatively easy engineering and mechanical flexibility, compatible with bending plastic substrates. In this thesis work we investigated the chemical, structural and electronic properties of cobalt phthalocyanines (CoPc). These molecules have promising applications in the field of magnetic data storage and spintronics in general, due to the ferromagnetic properties of the cobalt atom. Several techniques like photoemission core-level spectroscopy and valence band spectroscopy, together with X-ray absorption, have been used in order to determine the CoPc properties in gaseous phase, i.e. in the absence of interaction with the surrounding environment. Another set of experiments was devoted to the commissioning of the CITIUS time-resolved photoemission setup, that will be used in future studies of CoPc molecules on surfaces.
Found in: ključnih besedah
Keywords: Cobalt phthalocyanine (CoPc), photoemission spectroscopy (PES), X-ray absorption spectroscopy (XAS), synchrotron radiation, laser, high order harmonic generation (HHG), time resolved spectroscopy
Published: 29.09.2015; Views: 3881; Downloads: 183
.pdf Fulltext (2,96 MB)

Real-time motor unit identification from high-density surface EMG
Vojko Glaser, Aleš Holobar, Damjan Zazula, 2013, original scientific article

Abstract: This study addresses online decomposition of high-density surface electromyograms (EMG) in real-time. The proposed method is based on previouslypublished Convolution Kernel Compensation (CKC) technique and sharesthe same decomposition paradigm, i.e. compensation of motor unit action potentials and direct identification of motor unit (MU) discharges. In contrast to previously published version of CKC, which operates in batch mode and requires ~ 10 s of EMG signal, the real-time implementation begins with batch processing of ~ 3 s of the EMG signal in the initialization stage and continues on with iterative updating of the estimators of MU discharges as blocks of new EMG samples become available. Its detailed comparison to previously validated batch version of CKC and asymptotically Bayesian optimal Linear Minimum Mean Square Error (LMMSE) estimator demonstrates high agreementin identified MU discharges among all three techniques. In the case of synthetic surface EMG with 20 dB signal-to-noise ratio, MU discharges were identified with average sensitivity of 98 %. In the case of experimental EMG, real-time CKC fully converged after initial 5 s of EMG recordings and real-time and batch CKC agreed on 90 % of MU discharges, on average. The real-time CKC identified slightly fewer MUs than its batch version (experimental EMG, 4 MUs versus 5 MUs identified by batch CKC, on average), but required only 0.6 s of processing time on regular personal computer for each second of multichannel surface EMG.
Found in: ključnih besedah
Keywords: discharge pattern, high-density EMG, surface EMG, motor unit, real time decomposition
Published: 05.01.2016; Views: 2191; Downloads: 0

Horizon Shells and BMS-like soldering transformations
Martin O'Loughlin, Matthias Blau, 2016, original scientific article

Abstract: We revisit the theory of null shells in general relativity, with a particular emphasis on null shells placed at horizons of black holes. We study in detail the considerable freedom that is available in the case that one solders two metrics together across null hypersurfaces (such as Killing horizons) for which the induced metric is invariant under translations along the null generators. In this case the group of soldering transformations turns out to be infinite dimensional, and these solderings create non-trivial horizon shells containing both massless matter and impulsive gravitational wave components. We also rephrase this result in the language of Carrollian symmetry groups. To illustrate this phenomenon we discuss in detail the example of shells on the horizon of the Schwarzschild black hole (with equal interior and exterior mass), uncovering a rich classical structure at the horizon and deriving an explicit expression for the general horizon shell energy- momentum tensor. In the special case of BMS-like soldering supertranslations we find a conserved shell-energy that is strikingly similar to the standard expression for asymptotic BMS supertranslation charges, suggesting a direct relation between the physical properties of these horizon shells and the recently proposed BMS supertranslation hair of a black hole.
Found in: ključnih besedah
Keywords: Black Holes, Classical Theories of Gravity, Space-Time Symmetries
Published: 10.03.2016; Views: 2010; Downloads: 0
.pdf Fulltext (333,17 KB)

Flexible non-volatile optical memory thin-filmtransistor device with over 256 distinct levelsbased on an organic bicomponent blend
Gvido Bratina, Egon Pavlica, 2016, original scientific article

Abstract: Flexible non-volatile optical memory thin-filmtransistor device with over 256 distinct levelsbased on an organic bicomponent blendTim Leydecker1, Martin Herder2, Egon Pavlica3,GvidoBratina3,StefanHecht2*, Emanuele Orgiu1*and Paolo Samorì1*Organic nanomaterials are attracting a great deal of interest for use in flexible electronic applications such as logiccircuits, displays and solar cells. These technologies have already demonstrated good performances, but flexible organicmemories are yet to deliver on all their promise in terms of volatility, operational voltage, write/erase speed, as well asthe number of distinct attainable levels. Here, we report a multilevel non-volatile flexible optical memory thin-filmtransistor based on a blend of a reference polymer semiconductor, namely poly(3-hexylthiophene), and a photochromicdiarylethene, switched with ultraviolet and green light irradiation. A three-terminal device featuring over 256 (8 bitstorage) distinct current levels was fabricated, the memory states of which could be switched with 3 ns laser pulses.We also report robustness over 70 write–erase cycles and non-volatility exceeding 500 days. The device was implementedon a flexible polyethylene terephthalate substrate, validating the concept for integration into wearable electronics andsmart nanodevices.
Found in: ključnih besedah
Keywords: organic semiconductors time of flight
Published: 22.06.2016; Views: 2621; Downloads: 0
.pdf Fulltext (2,78 MB)

Time restrictions in forest operations planning
Boštjan Kepic, 2016, master's thesis

Abstract: This master’s thesis deals with annual harvest operations (AHO) planning with consideration of time restrictions. We developed five models of binary integer linear programming (BILP) that schedule working groups to harvest unit areas (HUAs) according to the lowest cost possible. Total AHO costs include felling and skidding costs, transportation costs, and machine relocation costs. The first model is based on the presumption that harvesting can be planned and executed freely throughout the year. In other four, scheduling was subject to time restrictions in HUAs and differed according to the extent of time restrictions. The second model takes into account time restrictions due to unfavourable natural conditions, the third model due to disturbance-free areas of animal species, the fourth and fifth model concurrently include the impact of time restrictions due to natural conditions and disturbance-free areas. The annual workplace time in Model 2 is reduced by 14.2 %, in Model 3 by 16.9 %, in Model 4 by 29.3 % and in Model 5 by 42.3 %. The model tool used to test all the models was designed in Microsoft Excel. All five models were tested with OpenSolver 2.7.1 software. Increasing the extent of time restrictions in forest operations reduces the utilization of the annual workplace time. In testing the second model, we demonstrated that with proper organisation of an AHO plan the planner can influence the working days fallout. In the other three models, we were able to ensure the implementation of AHO plan by introducing extra working groups. Further, we confirmed that time restrictions affect the scheduling of the working groups and the sequencing of tasks. The increases in total AHO costs were explained as an increase in working groups’ costs due to lower utilization rate, an increase in depreciation costs of machines and costs due to unrealized allowable annual cut and timber sales planned for the current year. We tested each model on two examples.
Found in: ključnih besedah
Keywords: time restrictions, binary integer programming, forestry, annual harvest operations planning, harvesting, scheduling working teams
Published: 20.09.2016; Views: 3079; Downloads: 163
.pdf Fulltext (4,11 MB)

About Time
Una Rebić, 2016, master's thesis

Abstract: The practical work of my master project about time was carried out as processbased experiments in practice. As a result, the thesis is a combination of theoretical research taken from several fields—examining the notion of time from perspective of psychology, sociology, science and spirituality. Alongside mentioned research the thesis pairs artistic practices associated with each field discussed— considering most significant artist and his/her practice or project(s) in which they explore time. The third layer of the thesis pairs each section with my own personal practice through experiments carried out in the process—each exploring time from a different perspective. Since the thesis is the final project of the study developed within a certain time frame, the last chapter discusses how I approached this project in regard to my artistic practice.
Found in: ključnih besedah
Keywords: time, perception, On Kawara, sociology, speed, Hamish Fulton, quantum entanglement, arrow of time, Hiroshi Sugimoto, spirituality, consciousness, Marina Abramović, Ulay
Published: 14.09.2016; Views: 1847; Downloads: 1
.pdf Fulltext (8,39 MB)

The role of local potential minima on charge transport in thin organic semiconductor layers
Egon Pavlica, Raveendra Babu Penumala, Bratina Gvido, 2016, original scientific article

Abstract: We have performed a systematic study of dependence of time-resolved photocurrent on the point of charge excitation within the organic semiconductor channel formed by two coplanar metal electrodes. The results confirm that spatial variation of electric field between the electrodes crucially determines transport of photogenerated charge carriers through the organic layer. Time-of-flight measurements of photocurrent demonstrate that the transit time of photogenerated charge carrier packets drifting between the two electrodes decreases with increasing travelling distance. Such counterintuitive result cannot be reconciled with the spatial distribution of electric field between coplanar electrodes, alone. It is also in contrast to expected role of space-charge screening of external electric field. Supported by Monte Carlo simulations of hopping transport in disordered organic semiconductor layer, we submit that the space-charge screens the external electric field and captures slower charge carriers from the photogenerated charge carrier packet. The remaining faster carriers, exhibit velocity distribution with significantly higher mean value and shorter transit time.
Found in: ključnih besedah
Keywords: Charge transport, Organic semiconductors, Time of flight, Mobility, Traps
Published: 23.12.2016; Views: 2493; Downloads: 0
.pdf Fulltext (950,46 KB)

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