Defuzzification of spatial fuzzy sets by feature distance minimization

We present a novel defuzzification method, i.e., a mapping from the set of fuzzy sets to the set of crisp sets, and we suggest its application to image processing. Spatial fuzzy sets are, e.g., useful as information preserving representations of objects in images. Defuzzification of such a spatial fuzzy set can be seen as a crisp segmentation procedure. With the aim to provide preservation of selected quantitative features of the fuzzy set, we define the defuzzification of a fuzzy set to be a crisp set which is as close as possible to the fuzzy set, where the distance measure on the set of fuzzy sets, that we propose for defuzzification, incorporates selected local and global features of the fuzzy sets. The distance measure is based on the Minkowski distance between feature representations of the sets. The distance minimization, performed in the suggested defuzzification method, provides preservation of the selected quantitative features of the fuzzy set. The method utilizes the information contained in the fuzzy representation for defining a mapping from the set of fuzzy sets to the set of crisp sets. If the fuzzy set is a representation of an unknown crisp original set, such that the selected features of the original set are preserved in the fuzzy representation, then the defuzzified set may be seen as an approximate reconstruction of the crisp original. We present four optimization algorithms, exhibiting different properties, for finding the crisp set closest to a given discrete fuzzy set. A number of examples, using both synthetic and real images, illustrate the main properties of the proposed method. An evaluation of both theoretical aspects of the method, and its results, is given.     

Sediment depth attenuation of biogenic phosphorus compounds measured by 31P NMR

Being a major cause of eutrophication and subsequent loss of water quality, the turnover of phosphorus (P) in lake sediments is in need of deeper understanding. A major part of the flux of P to eutrophic lake sediments is organically bound or of biogenic origin. This P is incorporated in a poorly described mixture of autochthonous and allochthonous sediment and forms the primary storage of P available for recycling to the water column, thus regulating lake trophic status. To identify and quantify biogenic sediment P and assess its lability, we analyzed sediment cores from Lake Erken, Sweden, using traditional P fractionation, and in parallel, NaOH extracts were analyzed using 31P NMR. The surface sediments contain orthophosphates (ortho-P) and pyrophosphates (pyro-P), as well as phosphate mono- and diesters. The first group of compounds to disappear with increased sediment depth is pyrophosphate, followed by a steady decline of the different ester compounds. Estimated half-life times of these compound groups are about 10 yr for pyrophosphate and 2 decades for mono- and diesters. Probably, these compounds will be mineralized to ortho-P and is thus potentially available for recycling to the water column, supporting further growth of phytoplankton. In conclusion, 31P NMR is a useful tool to asses the bioavailability of certain P compound groups, and the combination with traditional fractionation techniques makes quantification possible.     

User-defined schedulers for real-time concurrent objects

Scheduling concerns the allocation of processors to processes, and is traditionally associated with low-level tasks in operating systems and embedded devices. However, modern software applications with soft real-time requirements need to control application-level performance. High-level scheduling control at the application level may complement general purpose OS level scheduling to fine-tune performance of a specific application, by allowing the application to adapt to changes in client traffic on the one hand and to low-level scheduling on the other hand. This paper presents an approach to express and analyze application-specific scheduling decisions during the software design stage. For this purpose, we integrate support for application-level scheduling control in a high-level object-oriented modeling language, Real-Time ABS, in which executable specifications of method calls are given deadlines and real-time computational constraints. In Real-Time ABS, flexible application-specific schedulers may be specified by the user, i.e., developer, at the abstraction level of the high-level modeling language itself and associated with concurrent objects at creation time. Tool support for Real-Time ABS is based on an abstract interpreter that supports simulations and measurements of systems at the design stage.     

Pulse contour-derived cardiac output in hemodialysis patients

Reliable methods for cardiac output determination are essential for studying the pathophysiology of intradialytic hypotension. Use of the current gold standard, the Transonic^® monitor, requires an arteriovenous fistula. We wished to verify the accuracy of a method based on finger pulse contour analysis, namely the Finometer^® monitor (FNM) for further use on patients dialyzing on a central vascular catheter. Fifty simultaneous cardiac output measurements were obtained during hemodialysis sessions in 25 patients. The internal variability of the FNM measurements was assessed by comparing 24 pairs of immediately successive measurements. The variability of successive FNM measurements was small (bias 0.28%, SD ± 6.1%; NS). The absolute cardiac output values reported by the FNM were unreliable (bias 20.1%, SD ± 35.3%; P<0.001) as were the relative intradialytic changes (r²=0.01). Excluding participants from the analysis due to old age, high dialysis vintage or a suspicion of atherosclerosis did not improve the results. Our findings do not support the use of pulse contour analysis for measuring cardiac output in hemodialysis patients. Uremic vascular disease may be the cause of the observed inaccuracy.     

Inheritance patterns of phenolics in F1, F2, and back-cross hybrids of willows: implications for herbivore responses to hybrid plants

The aim of this study was to determine the inheritance pattern of phenolic secondary compounds in pure and hybrid willows and its consequences for plant resistance to leaf-feeding insects. F1, F2, and back-cross hybrids along with pure species were produced by hand pollination of pure, naturally-growing Salix caprea (L., Salicaceae) and S. repens (L.) plants. Leaf concentrations of condensed tannins and seven different phenolic glucosides were determined by using butanol-HCl and HPLC analyses. Insect herbivore leaf damage was measured on the same leaves as used for chemical analyses. We found hybrids to be approximately intermediate between the parental species: S. caprea with high levels of condensed tannins and no phenolic glucosides, and S. repens with low levels of condensed tannins and high levels of phenolic glucosides. We also found a negative correlation between concentrations of condensed tannins and phenolic glucosides, suggesting a trade-off in production of these two substances. F2 hybrids and the hybrid back-crossed to S. caprea were significantly more damaged by insect herbivores than the parental species and the F1 hybrid, indicating reduced resistance and possibly a selective disadvantage for these hybrid categories.     

A computationally convenient unit root test with covariates,conditional heteroskedasticity and efficient detrending

When testing for a unit root in a time series, in spite of the well‐known power problem of univariate tests, it is quite common to use only the information regarding the autoregressive behaviour contained in that series. In a series of influential papers, Elliott et al. (Efficient tests for an autoregressive unit root, Econometrica 64, 813–836, 1996), Hansen (Rethinking the univariate approach to unit root testing: using covariates to increase power, Econometric Theory 11, 1148–1171, 1995a) and Seo (Distribution theory for unit root tests with conditional heteroskedasticity, Journal of Econometrics 91, 113–144, 1999) showed that this practice can be rather costly and that the inclusion of the extraneous information contained in the near‐integratedness of many economic variables, their heteroskedasticity and their correlation with other covariates can lead to substantial power gains. In this article, we show how these information sets can be combined into a single unit root test.     

Quasi-static behaviour of composite joints with protruding-head bolts

An experimental study of the quasi-static behaviour of composite bolted joints under tensile and compressive loading has been performed. The joint plates made of quasi-isotropic and 0°-dominated lay-ups were fastened by two, four, or six titanium bolts. Two specimen configurations were tested: single lap and double lap. Strain gauges were applied in order to measure strain between the bolt rows and to calculate the load transfer of the bolt rows. Bolt-movement measurements were performed using extensometers to examine bolt behaviour under static loading. The obtained experimental results showed that bolted joints with four and six bolts perform better resistance to quasi-static loading than joints with two bolts. Strain distribution between two bolts is significantly affected by the bolt presence and their behaviour under loading. The load-transfer calculations showed that different bolt rows transfer slightly different amounts of load.     

Chemical composition and mass emission factors of candle smoke particles

The aim of this study is to investigate the physical and chemical properties of particle emissions from candle burning in indoor air. Two representative types of tapered candles were studied during steady burn, sooting burn and smouldering (upon extinction) under controlled conditions in a walk-in stainless steel chamber. Steady burn emits relatively high number emissions of ultrafine particles dominated by either phosphates or alkali nitrates. The likely source of these particles is flame retardant additives to the wick. Sooting burn in addition emits larger particles mainly consisting of agglomerated elemental carbon. This burning mode is associated with the highest mass emission factors. Particles emitted during smouldering upon extinction are dominated by organic matter. A mass closure was illustrated for the total mass concentration, the summed mass concentration from chemical analysis and the size-integrated mass concentration assessed from number distribution measurements using empirically determined effective densities for the three particle types.