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Determination of oxygen by means of a biogas and gas - interference study using an optical tris (4,7-diphenyl-1,10-phenanthroline) ruthenium(II) dichloride complex sensor
Polonca Brglez, Andrej Holobar, Aleksandra Pivec, Nataša Belšak, Mitja Kolar, 2012, original scientific article

Abstract: Biogas is a mixture of gases produced by anaerobic fermentation where biomass or animal waste is decomposed and methane and carbon dioxide are mainly released. Biogas also has a very high moisture content (up to 80%), temperatures of around 60 °C, high pressure, and can contain other gases ($N_2$, $H_2S$, $NH_3$ and $H_2$). We searched for an appropriate measuring system for the determining of oxygen in biogas, since the production process of biogas must be run under anaerobic conditions; as the presence of oxygen decreases the quality of the biogas. Ruthenium (II) complexes are by far the most widely-used oxygen dyes within optical oxygen sensors. In general, they have efficient luminescences, relatively long-life metal-ligand charge-transfer excited states, fast response times, strong visible absorptions, large Stokes shifts, and high-photochemical stability. The purpose of this work was to characterise and optimize an optical oxygen sensor using tris (4,7-diphenyl-1,10-phenanthroline) ruthenium(II) dichloride complex for measuring oxygen. Different sensor properties were additionally studied, focusing on the interference of external light, temperature, and various gases. A special gas-mixing chamber was developed for gas interference study, and online experiments are presented for oxygen determination within the pilot biogas reactor.
Keywords: tris(4, 7-diphenyl-1, 10-phenanthroline)ruthenium(II) dichloride complex, oxygen optical sensor, interferences, biogas
Published: 01.06.2012; Views: 1453; Downloads: 67
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3.
Characterisation of an optical sensor membrane based on the metal ion indication Pyrocatechol Violet
Ivana Murković Steinberg, Aleksandra Lobnik, Otto S. Wolfbeis, 2003, original scientific article

Abstract: A non-specific photometric metal ion indicator Pyrocatechol Violet (PV) was tested for its potential use in a metal-sensitive optrode membrane. The water soluble indicator was lipophilised in the form of an ion pair with tetraoctylammonium cation (TOA), and subsequently immobilised in a plasticised PVC membrane. The spectral response of the membrane in the presence of various transition metal ions was studied. It was found that the ability of PV to form complexes with metal ions significantly reduced following immobilisation, with the exception of Cu(II). A number of factors responsible for the improved selectivity and high sensitivity of immobilised PV towards Cu(II) were identified. Amongst those, the most important is the presence of quaternary ammonium salt in the membrane which induced a significant bathochromic shift of the PV-Cu(II) chelate absorption maximum, as well as the intensification of the chelate absorption band. The membrane responds to Cu(II) irreversibly by changing colour from yellow to green (absorption maximum at 740 nm), and typically, an exposure time of 10 min enables the determination of Cu(II) in the 1-100 M range. A comparison of selectivity and sensitivity characteristics between the water soluble form of the indicator and the immobilised form was performed, and the effects of pH and lipophilic surfactant additives on the response mechanism are discussed.
Keywords: optical sensors, sensor membrane, PVC membrane, photometric metal ion indicators, metal-sensitive optrode membrane, lipophilic ion pairs
Published: 01.06.2012; Views: 1086; Downloads: 21
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4.
Porosity sensor by using quartz crystals and two excitation signals
Vojko Matko, 2003, published scientific conference contribution

Abstract: In response to a need for a more accurate porosity measuring method for small solid samples (app. 1 g in mass) the porosity measurement sensor using a sensitive capacitive-dependent crystal was developed. This paper presents the new sensor and the probe sensitivity, frequency dependence on the volume. In addition, the new idea of excitation of the entire sensor with stochastic test signals is described, and the porosity measuring method is provided. The latter includes the influence of test signals on the weighting function uncertainty. The experimental results of the porosity determination in volcanic rock samples are presented. The uncertainty of porosity measurements is less than 0.1% in the temperature range 10 - 30°C.
Keywords: electrical measurements, porosity, soil, capacitive dependent crystals, sensor, glass test tube, direct digital method
Published: 01.06.2012; Views: 1366; Downloads: 83
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5.
System for precise balancing and controlled unbalancing of fiber-optic interferometers
Irvin Sirotić, Denis Đonlagić, 2002, original scientific article

Abstract: A system for accurate balancing and controlled unbalancing of the optical path difference in all-fiber optical interferometers is described. Interferometers with various arm lengths (1-30m) and with initial optical pathdifferences of as much as 1 cm have been successfully balanced within a 5 ▫$mu$▫m range. In addition, the proposed system allows for controlled unbalancing of arbitrary all-fiber optical interferometers with a precision better than 5 ▫$mu$▫m.
Keywords: electrical measurements, optical instruments, interferometers, fiber interferometers, optical path difference, sensor systems
Published: 01.06.2012; Views: 847; Downloads: 73
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6.
PRENOVA POSLOVNIH PROCESOV Z UVEDBO NOVEGA INFORMACIJSKEGA SISTEMA V PODJETJU SENSOR D.O.O.
Teja Mede, 2013, undergraduate thesis

Abstract: Danes se veliko podjetji bojuje z situacijo hitrega vzpona avtomatizacije in razvoja informacijske in komunikacijske tehnologije. Delo, ki se opravlja ročno postaja zamudno in neprofesionalno v očeh strank. Poleg tega ustvarja dodatne stroške. V takšni situaciji je potrebno spremeniti poslovni proces, ga avtomatizirati. Če se podjetje odloči za takšno potezo, je zelo pomembno, da pozna in razume pojme kot so poslovni proces, prenova procesov in informacijski sistem. Potrebno je prenovo znati načrtovati in jo tudi izpeljati. Podjetje Sensor je eno od podjetji, ki se sooča z neustrezno zasnovo trenutnih procesov in se zato odloči za prenovo poslovnih procesov z implementacijo informacijskega sistema. Problemi se kažejo pri sledenju zalog, pri opravljanju administrativnih del, inventuri in podobno. Takšna neprimernost vpliva na učinkovitost zaposlenih in predvsem na zadovoljstvo strank. S pomočjo omenjenega podjetja Sensor bomo spoznali proces prenove poslovnih procesov in njegov potek. Novi informacijski sistem in nove procese v podjetju bomo opazovali. Natančneje si bomo ogledali ključni proces podjetja, prodaja, pred in po prenovi procesov. Predstavili ga bomo v obliki diagrama in tako lažje prepoznali prednosti, ki jih je prinesla prenova poslovnih procesov. Spoznali bomo pomanjkljivosti prenove, ter možnosti za izboljšanje.
Keywords: poslovni proces, prenova poslovnih procesov, informatizacija, implementacija informacijskega sistema, podjetje Sensor.
Published: 17.10.2013; Views: 1408; Downloads: 213
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7.
MERJENJE BATERIJSKEGA TOKA V ELEKTRIČNIH VOZILIH Z UPOROM SHUNT
Benjamin Ferlinc, 2015, undergraduate thesis

Abstract: V diplomskem delu sem prikazal razvoj shunt senzorja za merjenje baterijskega toka v električnih vozilih. Predstavljen je sistem podjetja Emsiso, ki se vgrajuje v električna vozila. V tem sistemu je uporabljen shunt senzor. Opisana je težava, do sedaj uporabljenega senzorja s Hallovim pojavom. Predpostavljene so prednosti in slabosti shunt senzorja v primerjavi z senzorjem na osnovi Hallovega pojava. Predstavljen je celoten razvoj senzorja od izbire komponent, komunikacije, galvanske izolacije do izdelave tiskanine. Izračunana in izmerjena je natančnost izdelanega senzorja. Opisan je postopek meritve offseta in kalibracije senzorja.
Keywords: Shunt upor, shunt sensor, baterijski tok, električno vozilo, balanser
Published: 28.10.2015; Views: 1954; Downloads: 141
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8.
O kontaktni leči Sensor Triggerfish
Christoph Faschinger, Eva Faschinger, Sarah Krainz, Georg Mossböck, 2012, review article

Abstract: Namen prispevka je prikazati novo napravo, senzorsko kontaktno lečo Triggerfish, za stalno merjenje intraokularnega pritiska, dosedanje izkušnje in oceniti možnost njene uporabe. Prikazane so do sedaj objavljene raziskave na to temo. Naprava se dobro prenaša, je varna, preiskava se lahko ponovi. Do sedaj je še premalo podatkov, da bi jo lahko uporabljali že v vsakodnevni praksi pri zdravljenju glavkoma. Potrebne bodo še dodatne raziskave.
Keywords: intraocular pressure, sensor contact lens, safety, tolerability, reproducibility, validity
Published: 30.12.2015; Views: 462; Downloads: 24
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9.
High-precision hysteresis sensing of the quartz crystal inductance-to-frequency converter
Vojko Matko, Miro Milanovič, 2016, original scientific article

Abstract: A new method for the automated measurement of the hysteresis of the temperature-compensated inductance-to-frequency converter with a single quartz crystal is proposed. The new idea behind this method is a converter with two programmable analog switches enabling the automated measurement of the converter hysteresis, as well as the temperature compensation of the quartz crystal and any other circuit element. Also used is the programmable timing control device that allows the selection of different oscillating frequencies. In the proposed programmable method two different inductances connected in series to the quartz crystal are switched in a short time sequence, compensating the crystal’s natural temperature characteristics (in the temperature range between 0 and 50 °C). The procedure allows for the measurement of the converter hysteresis at various values of capacitance connected in parallel with the quartz crystal for the converter sensitivity setting at selected inductance. It, furthermore, enables the measurement of hysteresis at various values of inductance at selected parallel capacitance (sensitivity) connected to the quartz crystal. The article shows that the proposed hysteresis measurement of the converter, which converts the inductance in the range between 95 and 100 μH to a frequency in the range between 1 and 200 kHz, has only 7 × 10−13 frequency instability (during the temperature change between 0 and 50 °C) with a maximum 1 × 10−11 hysteresis frequency difference.
Keywords: inductance-to-frequency converter, hysteresis, automated measurement, sensor switching method, inductance, quartz crystal, temperature compensation
Published: 30.06.2016; Views: 1073; Downloads: 301
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10.
ERROR PROBABILITY MODEL FOR IEEE 802.15.4 WIRELESS TRANSMISSION WITH CO-CHANNEL INTERFERENCE AND BACKGROUND NOISE
Uroš Pešović, 2016, doctoral dissertation

Abstract: Data transmission sent through wireless channel is usually affected by background noise, multipath fading and interference which cause data errors. Influence of such disturbances is the most commonly expressed in a form of error probability statistics. Effects of these disturbances on IEEE 802.15.4 wireless transmissions are previously studied, except influence of co-channel interference (CCI) which originates from collision between IEEE 802.15.4 devices which perform simultaneous radio transmission. Our thesis puts forward the assumption that it is possible to derive more accurate analytical error probability model for higher data level error probability parameters without the idealization of PN spreading sequences. Additionally, thesis is that is possible to derive an accurate analytical error probability model in the case of CCI influenced by background noise by consideration of constellation diagram. IEEE 802.15.4 standard uses CSMA/CA (Carrier Sense Multiple Access with Collision Detection) channel access mechanism to prevent collisions between devices, but this mechanism doesn't provide protection from hidden node problem which is primary source of co-channel interference. Using Monte Carlo simulations we determined frequency of hidden node collisions, which shown that co-channel interference frequently occur in parts of the network with high traffic load. Some prior works in this field tend to idealize these non-ideal spreading sequences in order to simplify calculations for error probability parameters. Our doctor thesis presents analytical model of data level error probability parameters (symbol, bit and packet) for IEEE 802.15.4, which uses original non-ideal spreading sequences without their idealization. Proposed error probability model consists of mutually dependent chip, symbol, bit and packet error probability models. Derived error probability models are linked together, so each of error probability parameters can be determined using error probability parameter from the previous stage. Error probability model for IEEE 802.15.4 wireless communication could be used in network simulation tools in order to accurately simulate energy efficient medium access protocols in realistic scenarios. Presented theoretical results are tested by independent numerical simulation of IEEE 802.15.4 transmission according to Monte Carlo method. Simulation results shows that derived models for error probability parameters were matched by two simulation scenarios in background noise, for multipath fading and co-channel interface, respectively Furthermore, the accuracy of derived mathematical models was tested in real-world experiment using IEEE 802.15.4 compliant wireless transceivers for creating co-channel interference. Packets were received by software defined radio platform, which enabled realization of coherent receiver in which all error probability statistics could be collected. The results of the experiment show consistency with proposed analytical error probability models, but some deviations are caused by poor preamble synchronization under low SNR (Signal to Noise Ratio) value. The thesis was proved with Monte Carlo simulations of the physical level of the IEEE 802.15.4 communication and experimental measurements on a real physical communication system.
Keywords: IEEE 802.15.4 standard; error probability model; co-channel interference; Rician fading channel; additive white Gaussian noise; wireless transmission, wireless sensor networks, numerical simulations, software defined radio
Published: 14.10.2016; Views: 1201; Downloads: 66
.pdf Full text (8,20 MB)

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