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- Hasse, L, et al.
(författare)
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Quality assessment of varistor ZnO structures by resonant ultrasound spectroscopy
- 2009
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Ingår i: Insight. - : British Institute of Non-Destructive Testing (BINDT). - 1354-2575 .- 1754-4904. ; 51:5, s. 262-265
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Tidskriftsartikel (refereegranskat)abstract
- Varistors are produced from ZnO cylindrically-shaped structures whose quality depends on varying technological conditions at stages of their shape forming and firing. Therefore, the varistors art, tested at the final phase of production and faulty elements are excluded. We propose to test the quality of ZnO structures at an earlier stage of production to eliminate defective structures from further and expensive processing. The recommended method applies resonant ultrasound spectroscopy that meets the demand for limiting the costs introduced by an additional measurement procedure. This paper presents the prepared economical measurement system. that can be used for this purpose The proposed method measures one of the lowest resonant frequencies and dimensions of the tested specimen. The measured quantities enable the estimation of a parameter that is proportional to the sound velocity, in the tested ZnO sample and gives information about the quality of the ZnO structure. Detailed experimental data obtained for two batches of ZnO structures, oil purpose prepared in different ways, are analysed to confirm the usefulness of the applied procedure in industrial applications.
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- Heszler, P, et al.
(författare)
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On the Selectivity of Nanostructured Semiconductor Gas Sensors
- 2007
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Ingår i: Physica status solidi. B, Basic research. - : Wiley. - 0370-1972 .- 1521-3951. ; 244:11, s. 4331-4335
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Tidskriftsartikel (refereegranskat)abstract
- Different methods are presented for improving chemical selectivity and sensitivity of semiconductor gassensors consisting of nanostructured thin films. Pure and doped WO3 nanoparticles, forming nanoporouslayers, are used as test material. The chemical selectivity is increased by applying different operating tem-peratures, using temperature modulation and pattern recognition methods, and by a fluctuation enhancedspectroscopy technique. The selectivity improvement of a fluctuation enhanced sensor is compared to thatof a classical resistive sensor.
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- Kish, L. B., et al.
(författare)
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Critical remarks on Landauer's principle of erasure-dissipation : Including notes on Maxwell demons and Szilard engines
- 2015
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Ingår i: Proceedings. - 9781467383356
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Konferensbidrag (refereegranskat)abstract
- We briefly address Landauer's Principle and some related issues in thermal demons. We show that an error-free Turing computer works in the zero-entropy limit, which proves Landauer's derivation incorrect. To have a physical logic gate, memory or information-engine, a few essential components necessary for the operation of these devices are often neglected, such as various aspects of control, damping and the fluctuation-dissipation theorem. We also point out that bit erasure is typically not needed or used for the functioning of computers or engines (except for secure erasure).
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| 12. |
- Kish, L. B., et al.
(författare)
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Facts and myths about zero-point thermal noise, and information entropy versus thermal entropy
- 2017
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Ingår i: 2017 International Conference on Noise and Fluctuations (ICNF). - New York : IEEE. - 9781509027606 - 9781509027613
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Konferensbidrag (refereegranskat)abstract
- In this talk, we are briefly surveying our recent results [1-3] about two very popular yet often misunderstood concepts in physical informatics: (i) The existence of Johnson noise at near to absolute zero temperature has been debated many times yet it is generally accepted [1]. We point out the fundamental problems [2] with the particular approach the related quantum theories [4] of Fluctuation-Dissipation Theorem are using. Then we prove that the existence of zero-point noise would allow the construction of a perpetual motion machine [1]. Finally, we cite early works pointing out that the observed “zeropoint” noise in experiments [7] with phase-sensitive linear amplifiers is an amplifier-noise [5,6] due to the uncertainty principle, and it does not exist in the resistor in an objective way, independently from the measurement [1,2]. Thus a correct derivation of the Fluctuation-Dissipation Theorem must include [1] the type of experimental setup used for the measurement. (ii) The general opinion is that information entropy and thermal entropy are interchangeable. This belief triggered Brillouin's negentropy principle of information [8], and Landauer's claimed principle [9] about energy dissipation during information erasure that has been debated on many occasions [10-19]. Here we show the newest and perhaps the simplest arguments [3] proving that the two types of entropies are apples and oranges and are not interchangeable.
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- Kish, L. B., et al.
(författare)
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Waves in a short cable at low frequencies, or just hand-waving?
- 2015
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Ingår i: 2015 International Conference On Noise And Fluctuations (ICNF). - 9781467383356
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Konferensbidrag (refereegranskat)abstract
- We address the question of low-frequency signals in a short cable, which are often considered as waves in engineering calculations. Such an assumption violates several laws of physics, but exact calculations can be carried out via linear network theory.
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- Rehman, A., et al.
(författare)
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Generation-recombination and 1/f noise in carbon nanotube networks
- 2021
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 118:24
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Tidskriftsartikel (refereegranskat)abstract
- The low-frequency noise is of special interest for carbon nanotubes devices, which are building blocks for a variety of sensors, including radio frequency and terahertz detectors. We studied noise in as-fabricated and aged carbon nanotube networks (CNNs) field-effect transistors. Contrary to the majority of previous publications, as-fabricated devices demonstrated the superposition of generation-recombination (GR) and 1/f noise spectra at a low-frequency range. Although all the devices revealed identical current-voltage characteristics, GR noise was different for different transistors. This effect is explained by the different properties and concentrations of trap levels responsible for the noise. Unexpectedly, exposure of these devices to the atmosphere reduced both the resistance and GR noise due to nanotube's p-doping by adsorbed water molecules from the ambient atmosphere. The presence of the generation recombination noise and its dependences on the environment provides the basis for selective gas sensing based on the noise measurements. Our study reveals the noise properties of CNNs that need to be considered when developing carbon nanotubes-based selective gas sensors.
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- Smulko, J, et al.
(författare)
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Fluctuation-enhanced gas sensing in practice
- 2011
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Konferensbidrag (refereegranskat)abstract
- The technique of fluctuation-enhanced sensing (FES) in resistive gas sensors was proposed a few years ago. The method improves the selectivity and sensitivity of gas detection. This was confirmed in numerous laboratory experiments. Some of the latest results obtained for practical applications of the FES method are presented (toxic gases detection; problems of detection repeatability; detection of essential oils intensity during aromatherapy, biological agent detection). Additionally, a new prototype nanoparticle gas sensor was introduced with an additional potential of gas detection using noise induced by UV irradiations.
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| 16. |
- Smulko, J., et al.
(författare)
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Low-frequency noise in Au-decorated graphene-Si Schottky barrier diode at selected ambient gases
- 2023
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 122:21
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Tidskriftsartikel (refereegranskat)abstract
- We report results of the current-voltage characteristics and low-frequency noise in Au nanoparticle (AuNP)-decorated graphene-Si Schottky barrier diodes. Measurements were conducted in ambient air with addition of either of two organic vapors, tetrahydrofuran [(CH2)(4)O; THF] and chloroform (CHCl3), as also during yellow light illumination (592 nm), close to the measured particle plasmon polariton frequency of the Au nanoparticle layer. We observed a shift of the DC characteristics at forward voltages (forward resistance region) when tetrahydrofuran vapor was admitted (in a Au-decorated graphene-Si Schottky diode), and a tiny shift under yellow irradiation when chloroform was added (in not decorated graphene-Si Schottky diode). Significantly larger difference in the low-frequency noise was observed for the two gases during yellow light irradiation, compared with no illumination. The noise intensity was suppressed by AuNPs when compared with noise in graphene-Si Schottky diode without an AuNP layer. We conclude that flicker noise generated in the investigated Au-decorated Schottky diodes can be utilized for gas detection.
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