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Gintautas Miliauskas Vaidotas Sabanas Ramunas Bankauskas Giedrius Miliauskas Viktorija Sankauskaite 《International Journal of Heat and Mass Transfer》2008,51(17-18):4145-4160
The change of thermal state and phase transformation intensity of sprayed water, n-hexane, n-heptane and n-decane is numerically modelled in the case, as droplets are heated by conduction; the influence of the Knudsen layer is neglected; warming and evaporation of the droplets has no influence on the state of the carrying air flow. The research results prove that a peculiar change of the thermal state of sprayed liquid, irrespective of droplet’s dispersivity, exists in the time scale, expressed by Fourier number. The above-mentioned change can be conveniently defined by the characteristic curves, representing the change of a droplet surface, centre, and mean mass temperatures, which are sensibly influenced by temperature of gas mixture and partial pressure of liquid vapour in it. As these characteristic curves were expressed in regards to the initial and equilibrium evaporation temperatures of liquid, the universal curves, representing the change of thermal states of the examined liquids, were obtained in the time scale, expressed by Fourier number. It is shown that liquid evaporation rate and the change of a droplet dimension can also be described by characteristic curves. 相似文献
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Elena Jasiūnienė Vaidotas Cicėnas Paulius Grigaliūnas Žymantas Rudžionis Arūnas Aleksandras Navickas 《Materials and Structures》2018,51(4):103
The interest in potential applications produced with self-compacting fibre reinforced concrete continues to grow, but in practice, problems associated with an uneven distribution and orientation of fibres in the concrete structure occur. It is not clear what exactly influences uneven distribution of fibres in self-compacting concrete (SCC) mixtures, especially during the casting and how different factors influence fibre orientation. The objective of this work was to investigate how rheological properties influence the steel fibre distribution in self-compacting concrete. This work also focuses on the investigation of steel fibre spatial orientation dependence on rheological properties of SCC, while keeping other casting parameters and the proportions of mixture components constant. Mixtures with three different rheological properties were chosen based on slump flow, slump flow time t500 and static segregation values. The steel fibre orientation, volumetric concentration and spatial distribution values were determined in separate beam sections using three different non-destructive testing methods: electromagnetic induction, image analysis and computed tomography (CT scan). The comparison of the results is presented. The results show how different rheological properties of SCC affect the steel fibre orientation and distribution for the case of beams produced with the flow-induced casting method. 相似文献
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Marozas V Janusauskas A Lukosevicius A Sörnmo L 《IEEE transactions on bio-medical engineering》2006,53(8):1586-1593
This paper presents a unified approach to multiscale detection of transient evoked otoacoustic emissions (TEOAEs). Using statistical detection theory, it is shown that the optimal detector involves a time windowing operation where the window can be estimated from ensemble correlation information. The detector performs adaptive splitting of the signal into different frequency bands using either wavelet or wavelet packet decomposition. A simplified detector is proposed in which signal energy is omitted. The results show that the simplified detector performs significantly better than existing TEOAE detectors based on wave reproducibility or the modified variance ratio, whereas the detector involving signal energy does not offer such a performance advantage. 相似文献
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Carole Sentein Licinio Rocha Aleksandra Apostoluk Paul Raimond Iris Duyssens Ineke Van Severen Thomas Cleij Laurence Lutsen Dirk Vanderzande Vaidotas Kaukauskas Mindaugas Pranaitis Valius yras 《Solar Energy Materials & Solar Cells》2007,91(19):1816-1824
Storage of an internal field in a polymeric semiconductor device should be of great interest for applications like photovoltaic solar cells to facilitate exciton dissociation and improve charge transport in the structure. Orientation of polar molecules, contained inside a polymer binder, induces a rectifying effect, behaving as a distributed homojunction within a single polymeric film. To investigate this concept, a new poly(p-phenylenevinylene) (PPV) derivative bearing push–pull like molecules was purposefully designed and synthesized. Effect of polar molecules’ orientation on carrier injection and transport properties was studied. In the test systems, we demonstrate an increase of the external quantum efficiency upon orientation. 相似文献
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We propose a new procedure for white noise testing of a functional time series. Our approach is based on an explicit representation of the L2‐distance between the spectral density operator and its best (L2‐)approximation by a spectral density operator corresponding to a white noise process. The estimation of this distance can be easily accomplished by sums of periodogram kernels, and it is shown that an appropriately standardized version of the estimator is asymptotically normal distributed under the null hypothesis (of functional white noise) and under the alternative. As a consequence, we obtain a very simple test (using the quantiles of the normal distribution) for the hypothesis of a white noise functional process. In particular, the test does not require either the estimation of a long‐run variance (including a fourth order cumulant) or resampling procedures to calculate critical values. Moreover, in contrast to all other methods proposed in the literature, our approach also allows testing for ‘relevant’ deviations from white noise and constructing confidence intervals for a measure that measures the discrepancy of the underlying process from a functional white noise process. 相似文献
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