280 research outputs found
Comment on Stallinga, P. (2023), Residence Time vs. Adjustment Time of Carbon Dioxide in the Atmosphere
No full textThe goal of Stallinga (2023), to address confusion about CO2 "residence time" and "adjustment time," is laudable. Unfortunately, the author, himself, has confused them. Dr. Stallinga made two key errors, the second following from the first. His first and most important mistake was his claim that, "the adjustment time is never larger than the residence time." That is backward. It is easily shown that the adjustment time is much longer than the residence time, because some of the processes which reduce the residence time do not reduce the adjustment time. He also wrote that neither the residence time nor the adjustment time is "longer than about 5 years." That is correct only for the residence time. It is wrong by a full order of magnitude for the adjustment time. The adjustment time can be determined from measurements, and it is approximately fifty years
The effect of water related traps on the reliability of organic based transistors
No full textThe electrical stability of metal-insulator semiconductor (MIS) capacitors and field-effect transistor structures based in organic semiconductors were investigated. The device characteristics were studied using steady state measurements AC admittance measurements as well as techniques for addressing trap states. Temperature-dependent measurements show clear evidence that an electrical instability occurs above 200 K and is caused by an electronic trapping process. Experimental results show that water is responsible for the trapping mechanism. (c) 2006 Elsevier B.V. All rights reserved
Electronic Transport in Field Effect Transistors of Sexithiophene
No full textThe electronic conduction of thin-film field-effect-transistors (FETs) of sexithiophene was studied. In most cases the transfer curves deviate from standard FET theory; they are not linear, but follow a power law instead. These results are compared to conduction models of "variable-range hopping" and "multi-trap-and-release". The accompanying IV curves follow a Poole-Frenkel (exponential) dependence on the drain voltage. The results are explained assuming a huge density of traps. Below 200 K, the activation energy for conduction was found to be ca. 0.17 eV. The activation energies of the mobility follow the Meyer-Neldel rule. A sharp transition is seen in the behavior of the devices at around 200 K. The difference in behavior of a micro-FET and a submicron FET is shown. (C) 2004 American Institute of Physics
Software for Simultaneous orientation and 3D localization microscopy with a Vortex point spread function
No full textThis code is distributed as accompanying software for the article Simultaneous orientation and 3D localization microscopy with a Vortex point spread function by Christiaan N. Hulleman, Rasmus Ø. Thorsen, Eugene Kim, Cees Dekker, Sjoerd Stallinga, and Bernd Rieger.Any reuse of this code should cite the original associated publication.</p
Electrical instabilities in organic semiconductors caused by trapped supercooled water
No full textIt is reported that the electrical instability known as bias stress is caused by the presence of trapped water in the organic layer. Experimental evidence as provided by the observation of an anomaly occurring systematically at around 200 K. This anomaly is observed in a variety of materials, independent of the deposition techniques and remarkably coincides with a known phase transition of supercooled water. Confined water does not crystallize at 273 K but forms a metastable liquid. This metastable water behaves electrically as a charge trap, which causes the instability. Below 200 K the water finally solidifies and the electrical traps disappear. (c) 2006 American Institute of Physics
Electrical characterization of organic based transistors: stability issues
No full textAn investigation into the stability of metal insulator semiconductor (MIS) transistors based on alpha-sexithiophene is reported. In particular the kinetics of the threshold voltage shift upon application of a gate bias has been determined. The kinetics follow a stretched-hyperbola type behavior, in agreement with the formalism developed to explain metastability in amorphous-silicon thin film transistors. Using this model, quantification of device stability is possible. Temperature-dependent measurements show that there are two processes involved in the threshold voltage shift, one occurring at T approximate to 220 K and the other at T approximate to 300 K. The latter process is found to be sample dependent. This suggests a relation between device stability and alpha-sexithiophene deposition parameters. Copyright (c) 2005 John Wiley A Sons, Ltd
Drift kappenspuit bij onkruidbestrijding in de boomteelt : veldmetingen 2011
No full textVoor neerwaartse bespuitingen in de boomteelt (laan - en parkbomen, bos - en haagplantsoen, vruchtbomen, rozestruiken, sierconiferen, etc.) wordt nu gebruik gemaakt van de driftcijfers voor veldspuiten. Deze driftcijfers zijn afgeleid van bespuitingen in aardappelen met een veldspuit. Onkruidbestrijding wordt in de boomteelt echter vooral uitgevoerd met spuitboompjes die laag boven het grondoppervlak (max. 3 0 cm) bewegen met neerwaarts gerichte spuitdoppen. Aangenomen mag worden dat de drift bij deze toepassing aanzienlijk lager zal zijn dan bij een bespuiting van aardappelen (50 cm boomhoogte boven een gewas van 50 - 75 cm hoog). Om de optredende drift bij onkruidbespuitingen in de boomteelt te kwantificeren en aan te tonen dat de drift lager is dan het nu gehanteerde driftpercentage in het Toelatingsbeleid (Ctgb, 2012; 1% driftdepositie op wateroppervlak) zijn in 2010 en 2011 veldmetingen uitgevo erd in een perceel laanbomen (Stallinga et al. , 2012). De percelen waren beschikbaar omdat daar driftmetingen bij gebruik van een mastspuit in de hoge laanbomen uitgevoerd werden (Stallinga et al. , 2011). In de boomteelt worden bespuitingen ook uitgevoerd met een zogenaamde kappenspuit. De spuitdoppen worden hierbij afgeschermd met een kap, zodat uitsluitend het onkruid geraakt wordt en niet de gewasplanten. Om de mate van driftbeperking door een kappenspuit vast te stellen zijn in 2011 veldmetingen uitgevoerd
Image based aberration retrieval using helical point spread functions
No full textA practical method for determining wavefront aberrations in optical systems based on the acquisition of an extended, unknown object is presented. The approach utilizes a conventional phase diversity approach in combination with a pupil-engineered, helical point spread function (PSF) to discriminate the aberrated PSF from the object features. The analysis of the image’s power cepstrum enables an efficient retrieval of the aberration coefficients by solving a simple linear system of equations. An extensive Monte Carlo simulation is performed to demonstrate that the approach makes it possible to measure low-order Zernike modes including defocus, primary astigmatism, coma, and trefoil. The presented approach is tested experimentally by retrieving the two-dimensional aberration distribution of a test setup by imaging an extended, unknown scene.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.ImPhys/Computational ImagingImPhys/Imaging Physic
Drift kappenspuit bij onkruidbestrijding in de boomteelt : veldmetingen 2011
No full textVoor neerwaartse bespuitingen in de boomteelt (laan - en parkbomen, bos - en haagplantsoen, vruchtbomen, rozestruiken, sierconiferen, etc.) wordt nu gebruik gemaakt van de driftcijfers voor veldspuiten. Deze driftcijfers zijn afgeleid van bespuitingen in aardappelen met een veldspuit. Onkruidbestrijding wordt in de boomteelt echter vooral uitgevoerd met spuitboompjes die laag boven het grondoppervlak (max. 3 0 cm) bewegen met neerwaarts gerichte spuitdoppen. Aangenomen mag worden dat de drift bij deze toepassing aanzienlijk lager zal zijn dan bij een bespuiting van aardappelen (50 cm boomhoogte boven een gewas van 50 - 75 cm hoog). Om de optredende drift bij onkruidbespuitingen in de boomteelt te kwantificeren en aan te tonen dat de drift lager is dan het nu gehanteerde driftpercentage in het Toelatingsbeleid (Ctgb, 2012; 1% driftdepositie op wateroppervlak) zijn in 2010 en 2011 veldmetingen uitgevo erd in een perceel laanbomen (Stallinga et al. , 2012). De percelen waren beschikbaar omdat daar driftmetingen bij gebruik van een mastspuit in de hoge laanbomen uitgevoerd werden (Stallinga et al. , 2011). In de boomteelt worden bespuitingen ook uitgevoerd met een zogenaamde kappenspuit. De spuitdoppen worden hierbij afgeschermd met een kap, zodat uitsluitend het onkruid geraakt wordt en niet de gewasplanten. Om de mate van driftbeperking door een kappenspuit vast te stellen zijn in 2011 veldmetingen uitgevoerd
Optical trapping at low numerical aperture
No full textA theory of optical trapping at low Numerical Aperture (NA) is presented. The theory offers an analytical description of the competition between the stabilizing gradient and destabilizing scattering force. The trade-off can be characterized by a single dimensionless trapping parameter, which increases with bead size to wavelength ratio ?/?, m, NA and refractive index contrast m and decreases with NA. The gradient force dominates for small trapping parameters, the scattering force for large trapping parameters. The potential well depth, maximum forces and trap stiffness as a function of the three parameters (?/?, m, NA ) can be mapped onto universal functions of the trapping parameter. These functions do not depend on any free parameter. The universal well depth and maximum force curves match with numerical results based on the exact multipole expansion of the optical trapping force. The paraxial limit of low NA is relevant for compact optical tweezers based on Optical Pickup Units known from optical data storage.Imaging Science & TechnologyApplied Science
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