Open-Source Systems for Computer Recognition of Audio Files

V diplomskem delu predstavljam področje računalniške prepoznave zvočnih zapisov, v katerega sodijo vedno bolj popularne aplikacije, kot je Shazam, ki uporabniku omogočajo prepoznavo glasbe, ki se predvaja v njihovi okolici. Sistemi prepoznavo nepoznanega zvočnega zapisa opravljajo na podlagi primerjave zgoščenih povzetkov oziroma odtisov zvočnega zapisa (angl.: acoustic/audio fingerprint), ki jih izdelajo iz krajših vzorcev nepoznanega zapisa in jih primerjajo s shranjenimi odtisi v katalogu poznanih referenčnih skladb. Pri tem se srečujejo z mnogimi težavami. Želimo namreč, da bodo sistemi za prepoznavo posnetek pravilno prepoznali tudi, če je stisnjen s pomočjo izgubnih kompresijskih postopkov, je v njem prisoten okoliški šum, motnje ali degradacije v kakršni koli drugi obliki. Pomembno je tudi, da prepoznavo vršijo hitro in učinkovito, kar pa glede na velike količine referenčnih skladb, ki jih katalogi običajno vsebujejo, ni preprosta naloga. V delu sem raziskal področja uporabe tehnologije ter princip delovanja temu namenjenih algoritmov. Pri tem sem podrobneje preučil lastnosti in zahteve, ki jim morajo zadostiti algoritmi, opisal sem težave s katerimi se algoritmi spopadajo pri zagotavljanju robustnosti in načine reševanja le-teh. Obravnavam tudi učinkovitost in natančnosti prepoznave. V nadaljevanju se osredotočam na primerjavo treh odprtokodnih sistemov: SoundFingerprinting, Echoprint in Dejavu. Izbrane sisteme in algoritme, na katerih le-ti temeljijo, sem podrobneje analiziral in preizkusil. Preizkuse sem opravil z izvedbo premišljenih testnih korakov, s katerimi sem razkril prednosti in slabosti posameznega sistema. V prvi fazi preizkusov sem preveril splošne lastnosti sistemov, ki vplivajo na primernost sistema za uporabo v različnih tipih aplikacij. Določil sem najmanjšo dolžino vzorca zvočnega posnetka, iz katerega je posamezen sistem zmožen zanesljivo opraviti prepoznavo. Na podlagi statistične analize rezultatov izvedbe prepoznave na naboru večjega števila testnih posnetkov sem ovrednotil lastnosti sistemov. Preveril sem, kako dobro sistemi ločujejo različne izvedbe iste skladbe in v kolikšni meri so odporni na različne tipe motenj in degradacij zvočnega signala. V nadaljevanju sem opravil še preizkus prepoznave predvajanih skladb v radijskih programih, s katerim sem preveril ustreznost posameznega sistema za uporabo v aplikaciji za izdelavo sporeda predvajanih skladb. V zaključku podajam lastno oceno primernosti posameznega sistema za uporabo v različnih tipih aplikacij in predlagam možnosti za izboljšave sistemov.This thesis describes automatic content recognition, an identification technology used to recognize content played in the vicinity of the user or on a media device. It focuses on systems for audio content recognition based on audio fingerprinting technology that is used by increasingly popular applications such as Shazam. An audio fingerprint is a condensed summary made from musical features extracted from a short sample of sound recording. It is used to identify an unknown sound recording by means of comparison of its fingerprints to a collection of fingerprints gathered from known recordings stored in a reference database. In doing so, the systems may encounter many obstacles. A system should be able to recognize an unknown recording regardless of the level of compression, surrounding noise present in the signal or any other form of degradation. It is also important that systems are able to perform identification fast and effectively, what is not a trivial task because systems usually contain a large number of reference tracks. I explored the scope of the technology and the principle of operation of dedicated algorithms. In doing so, I examined the characteristics and requirements that need to be satisfied by algorithms to ensure robustness, effectiveness and accuracy of identification. The main focus of the thesis is a comparison of three open-source systems: SoundFingerprinting, Echoprint and Dejavu. I have performed a detailed analysis of the selected systems and algorithms on which they are based. I also performed test procedures designed to reveal the strengths and weaknesses of each system. In the first testing stage, I verified the overall system properties that affect the suitability of the system for the use in different types of applications. For each system I measured the minimum length of audio clip required for a reliable identification. Based on the statistical analysis of data obtained during an identification test performed on large set of musical recordings, I evaluated the general performance of the systems. Later on I checked how well they distinguish different versions of the same song and to what extent they are resistant to interference and degradation of the audio signal. Lastly I examined the suitability of selected systems for the use in a broadcast monitoring system by means of performing audio recognition on radio broadcast recordings, which resulted in the creation of a playlist containing recognized songs. To conclude I present my own opinion on the suitability of each system for usage in different types of applications. I also suggest possible enhancements that could be made on systems to improve their performance

Stabilising a nulling interferometer using optical path difference dithering

Context. Nulling interferometry has been suggested as the underlying principle for the Darwin and TPF-I exoplanet research missions. Aims. There are constraints both on the mean value of the nulling ratio, and on its stability. Instrument instability noise is most detrimental to the stability of the nulling performance. Methods. We applied a modified version of the classical dithering technique to the optical path difference in the scientific beam. Results. Using only this method, we repeatedly stabilised the dark fringe for several hours. This method alone sufficed to remove the 1/ f component of the noise in our setup for periods of 10 minutes, typically. These results indicate that performance stability may be maintained throughout the long-duration data acquisitions typical of exoplanet spectroscopy. Conclusions. We suggest that further study of possible stabilisation strategies should be an integral part of Darwin/TPF-I research and developmen

Modeling the η Corvi debris disk from the sub-AU scale to its outermost regions

Dusty debris disks surrounding main sequence stars are thought to be analogues to thepopulations of small bodies of the Solar System (asteroids, comets/icy bodies and dust grains), however with often much higher masses and associated dust production rates. Mecanisms such as massive collisions or LHB-like events must therefore be invoked to justify their existence. This is especially striking for the nearby F2V star η Corvi that shows a very strong mid- and far-infrared excess despite an estimated age of ~1.4 Gyr (Lisse et al. 2012, Wyatt et al. 2005). We present new observations of the η Crv debris disk obtained in the far-infrared with Herschel/PACS and SPIRE and in the mid-infrared with the Keck Interferometer Nuller (Millan-Gabet et al. 2011). The Herschel/PACS images at 70, 100 and 160 μm reveal a well resolved belt of cold material at ~130 AU, as well as an unresolved component in the innermost parts of the system. This warmer counterpart is resolved in the mid-infrared as a strong null excess originating from within the ~2x4 AU field-of-view of the interferometer, which is reminiscent of the architecture of the Fomalhaut debris disk (Mennesson et al. 2012, Lebreton et al. 2013). The signature of warm silicate dust is also very clear in Spitzer/IRS high-resolution spectra (Chen et al. 2006) at intermediate wavelengths (10-35 μm). We undertake to establish a consistent model of the debris disk from the sub-AU scale to its outermost regions using the GRaTer radiative transfer code (Augereau et al. 1999a, Lebreton et al. 2013) by adjusting simultaneously the interferometric nulls, the resolved Herschel images and the spectro-photometric data against a large parameter space. Our analysis providesaccurate estimates of the fundamental parameters of the disk: its surface density profile, grain size distribution and mass, making it possible to unveil the origin of the dust and the relation between the cold (~50 K) Kuiper-like belt and the warm (~500 K) exo-zodiacal disk. We further discuss the possible existence of an additional dust population at intermediate temperatures and its nature. η Corvi will be of prime interest for future observations with the JWST. We finally make predictions of the ability of NIRCam and MIRI to image details in the disk at high contrast with both spatial and spectral resolution in order to obtain a better view of this complex planetary system

Supramolecular structures based on regiosisomers of cinnamyl-α-cyclodextrins - new media for capillary separation techniques

This work focuses on the preparation and application of supramolecular structures based on mono-cinnamyl-α-cyclodextrins (Cin-α-CD). Pure regioisomers of Cin-α-CD having the cinnamyl moiety at the 2-O- or at the 3-O-position, respectively, were prepared, characterized and applied in capillary electrophoresis as additives to the background electrolyte. These new monomer units with a potential to self-organize into supramolecular structures were synthesized via a straightforward one-step synthetic procedure and purified using preparative reversed-phase chromatography allowing a large scale separation of the regioisomers. The ability of the monomers to self-assemble was proved by various methods including NMR spectroscopy and dynamic light scattering (DLS). The light scattering experiments showed that the monomer units have distinguishable ability to form supramolecular structures in different solvents and the size distribution of the aggregates in water can be easily modulated using different external stimuli, such as temperature or competitive guest molecules. The obtained results indicated that the two regioisomers of Cin-α-CD formed different supramolecular assemblies highlighting the fact that the position of the cinnamyl group plays an important role in the intermolecular complex formation

Tests of achromatic phase shifters performed on the SYNAPSE test bench: a progress report

The achromatic phase shifter (APS) is a component of the Bracewell nulling interferometer studied in preparation for future space missions (viz. Darwin/TPF-I) focusing on spectroscopic study of Earth-like exo-planets. Several possible designs of such an optical subsystem exist. Four approaches were selected for further study. Thales Alenia Space developed a dielectric prism APS. A focus crossing APS prototype was developed by the OCA, Nice, France. A field reversal APS prototype was prepared by the MPIA in Heidelberg, Germany. Centre Spatial de Li\`ege develops a concept based on Fresnel's rhombs. This paper presents a progress report on the current work aiming at evaluating these prototypes on the SYNAPSE test bench at the Institut d'Astrophysique Spatiale in Orsay, France

Coworking spaces and mid-sized cities in peripheral contexts: Conceptualising development trajectories

Coworking spaces and the creative industries represent a rapidly growing but highly diverse shared economy sector. The paper outlines the types of incremental or radical forms of change developed that lead to industrial–institutional coevolution based on evidence from selected cities in Central and Eastern Europe. The results suggest that CS in peripheral areas are contributing primarily to the path upgrading through local embeddedness of stakeholders. These spaces contribute to refocusing local creative ecosystems by enhancing competitiveness of microclusters. Results suggest that CS in peripheral areas are contributing primarily to the path upgrading through local embeddedness of stakeholders through remote workers and digital nomads These cases underline replicative entrepreneurship, where local stakeholders gather momentum for a subsequent period characterised by new internal structures and services in the urban setting. Considering the form of change, our results emphasise the importance of reproductive agency based on diverse services to digital nomads and remote workers.Ministerstvo scaron;kolstva, vedy, vskumu a scaron;portu Slovenskej republik

The Potential of the Diarsene Complex [(C5H5)2Mo2(CO)4(µ,ƞ2-As2)] as a Connector Between Silver Ions

The reaction of the organometallic diarsene complex [Cp2Mo2(CO)(4)(mu,eta(2)-As-2)] (B) (Cp = C5H5) with Ag[FAl{OC6F10(C6F5)}(3)] (Ag[FAl]) and Ag[Al{OC(CF3)(3)}(4)] (Ag[TEF]), respectively, yields three unprecedented supramolecular assemblies [(eta(2)-B)(4)Ag-2][FAl](2)(4), [(mu,eta(1):eta(2)-B)(3)(eta(2)-B)(2)Ag-3][TEF](3)(5) and [(mu,eta(1):eta(2)-B)(4)Ag-3][TEF](3)(6). These products are only composed of the complexes Band Ag-I. Moreover, compounds 5and6are the only supramolecular assemblies featuringBas a linking unit, and the first examples of [Ag-I](3)units stabilized by organometallic bichelating ligands. According to DFT calculations, complex Bcoordinates to metal centers through both the As lone pair and the As-As sigma-bond thus showing this unique feature of this diarsene ligand

Mixed Organometallic‐Organic Hybrid Assemblies Based on the Diarsene Complex [Cp2Mo2(CO)4(µ,ƞ2‐As2)], Ag(I) salts and N‐Donor Organic molecules

The reaction of the organometallic diarsene complex [Cp 2 Mo 2 (CO) 4 ( h 2 ‐As 2 )] ( 1 ) (Cp = C 5 H 5 ) with Ag[Al{OC(CF 3 ) 3 } 4 ] (Ag[TEF]) yielded the Ag(I) monomer [Ag( h 2 ‐ 1 ) 3 ][TEF] ( 2 ). This compound exhibits a dynamic behaviour in solution, a feature that allows to direct a selective synthesis of unprecedented organometallic‐organic hybrid assemblies upon its reaction with N‐donor organic molecules possessing a stepwise pathway, which is supported by DFT calculations. Accordingly, the reaction of 2 with 2,2 ´ ‐bipyrimidine ( L1 ) yielded the dicationic molecular compound [{( h 2 ‐ 1 ) 2 Ag} 2 ( µ , L1 )][TEF] 2 ( 3 ) or the 1D polymer [{( h 2 ‐ 1 )Ag}( µ , L1 )] n [TEF] n ( 4 ) depending on the ratio of the used reactants. However, its reaction with the pyridine‐based linkers 4,4 ´ ‐bipyridine ( L2 ), 1,2‐di(4‐pyridyl)ethylene ( L3 ) and 1,2‐di(4‐pyridyl)ethyne ( L4 ) allowed the formation of the 2D polymers [{( h 2 ‐ 1 )Ag} 2 ( µ , Lx ) 3 ] n [TEF] 2n ( Lx = L2 ( 5 ), L3 ( 6 ), L4 ( 7 )), respectively. Additionally, this concept was extended to step‐by‐step one‐pot reactions of 1 , [Ag(CH 3 CN) 3 ][Al{OC(CF 3 ) 2 (CCl 3 )} 4 ] ([Ag(CH 3 CN) 3 ][TEF Cl ]) and the linkers L2 ‐ L4 , producing the 2D polymers [{( h 2 ‐ 1 )Ag} 2 ( µ , Lx ) 3 ] n [TEF Cl ] 2n ( Lx = L2 ( 8 ), L3 ( 9 ), L4 ( 10 )), respectively

Microcavity-integrated graphene photodetector

The monolithic integration of novel nanomaterials with mature and established technologies has considerably widened the scope and potential of nanophotonics. For example, the integration of single semiconductor quantum dots into photonic crystals has enabled highly efficient single-photon sources. Recently, there has also been an increasing interest in using graphene - a single atomic layer of carbon - for optoelectronic devices. However, being an inherently weak optical absorber (only 2.3 % absorption), graphene has to be incorporated into a high-performance optical resonator or waveguide to increase the absorption and take full advantage of its unique optical properties. Here, we demonstrate that by monolithically integrating graphene with a Fabry-Perot microcavity, the optical absorption is 26-fold enhanced, reaching values >60 %. We present a graphene-based microcavity photodetector with record responsivity of 21 mA/W. Our approach can be applied to a variety of other graphene devices, such as electro-absorption modulators, variable optical attenuators, or light emitters, and provides a new route to graphene photonics with the potential for applications in communications, security, sensing and spectroscopy.Comment: 19 pages, 4 figure