A filtered tabulated chemistry model for LES of premixed combustion

A new modeling strategy called F-TACLES (Filtered Tabulated Chemistry for Large Eddy Simulation) is developed to introduce tabulated chemistry methods in Large Eddy Simulation (LES) of turbulent premixed combustion. The objective is to recover the correct laminar flame propagation speed of the filtered flame front when subgrid scale turbulence vanishes as LES should tend toward Direct Numerical Simulation (DNS). The filtered flame structure is mapped using 1-D filtered laminar premixed flames. Closure of the filtered progress variable and the energy balance equations are carefully addressed in a fully compressible formulation. The methodology is first applied to 1-D filtered laminar flames, showing the ability of the model to recover the laminar flame speed and the correct chemical structure when the flame wrinkling is completely resolved. The model is then extended to turbulent combustion regimes by including subgrid scale wrinkling effects in the flame front propagation. Finally, preliminary tests of LES in a 3-D turbulent premixed flame are performed.     

Fasting and post-methionine load homocyst(e)ine values are correlated with microalbuminuria and could contribute to worsening vascular damage in non-insulin-dependent diabetes mellitus patients

The study aim was to assess the relationship between homocyst(e)inemia and microalbuminuria in non-insulin-dependent diabetes mellitus (NIDDM) patients. The study was performed on 33 NIDDM patients (16 males and 17 females), and 16 healthy control subjects (seven males and nine females). Plasma fasting and post-methionine load homocyst(e)ine (tHcy), together with other parameters that could modify tHcy levels, were assessed. There were no significant differences between NIDDM patients and controls for fasting tHcy (8.12 +/- 3.17 v 7.19 +/- 2.40 micromol/L) and post-methionine load tHcy (26.51 +/- 11.50 v 25.06 +/- 10.76 micromol/L). Moreover, there was a significant correlation between urinary albumin excretion (UAE) and fasting tHcy (r = .340, P = .05) and post-methionine load tHcy (r = .502, P = .004) in NIDDM patients. Fasting tHcy was correlated both with post-methionine load tHcy (r = .429, P = .01) and with vitamin B12 (r = -.349, P = .04) in NIDDM patients. Microalbuminuric NIDDM patients had higher fasting tHcy (9.05 +/- 3.83 micromol/L) than normoalbuminurics (7.12 +/- 1.95 micromol/L). In addition, NIDDM patients with complications presented higher fasting tHcy values than the group without complications (9.61 +/- 3.34 v 6.53 +/- 2.09 micromol/L, Kolmogorov-Smirnov two-sample test for nonparametric data [KS] = 1.794, P = .003), without any other significant differences in the parameters considered. tHcy could be an important risk factor worsening the prognosis in NIDDM patients, especially microalbuminuric patients. Microalbuminuric NIDDM patients could be particularly prone to hyperhomocyst(e)inemia, probably due to endothelial or renal dysfunction with a reduction in the scavenging of tHcy.     

Doppler echocardiographic study of left ventricular function in patients with systemic lupus erythematosus

This study was aimed at investigating abnormalities in left ventricular size and function in patients with systemic lupus erythematosus without overt cardiovascular manifestations, in order to detect a very early impairment in myocardial function. Seventeen females and 1 male with systemic lupus erythematosus of 4 to 20 year duration and without clinical evidence of heart disease were studied. Twelve healthy volunteers, matched for age, sex and quatelet index, were utilized as controls. Each patient had a two-dimensional M-mode echocardiographic and Doppler examination. In patients with systemic lupus erythematosus there was an increase in left ventricular ejection fraction (p < 0.001), a slight reduction of end-diastolic volume index and a significant decrease of end-systolic volume index (p < 0.001). In the same patients we also found prolongation of the isovolumic relaxation time (p < 0.02), a clear impairment of diastolic filling parameters. Peak E velocity was lower (p < 0.01), peak A velocity was higher (p < 0.01), with a clear lowering, of the corresponding E/A ratio (p < 0.001) in patients with systemic lupus erythematosus.     

A direct approach to jump detection in linear time-invariant systems with application to power system perturbation detection

A new direct approach to jump detection in linear time-invariant stochastic systems is considered in this paper, leading to a class of simple detection algorithms based on the explicit computation of the generalized likelihood ratio. While most of the already known methods perform the detection by observing the residuals of the Kalman-Bucy filter, here the output of the system is directly used for the detection, obtaining a larger class of algorithms which seems particularly convenient when state estimation is not required. Though the present approach is suitable only for time-invariant systems, its great flexibility allows the algorithm to be tightened to a particular application by changing such fundamental parameters as time-delay and observation interval. The practical application of the method to power systems perturbation detection is developed in the second part of the paper, where simulation results are presented as well. The discussion of the application shows as a precise qualification of the performance in terms of false alarm rate and probability of detection yields simple design criteria for the algorithm.     

Aerobiologic particle sampling by a new personal collector (Partrap FA52) in comparison to the Hirst (Burkard) sampler

A new personal portable sampler of biologic particles (Partrap FA52, Coppa, Biella, Italy) was used for pollen sampling in comparison with Hirst's (Burkard) fixed device. The aerobiologic samplings were carried out simultaneously outdoors with the two devices coupled on the same axis, during the daytime of 10 dry, nonconsecutive spring days. The total amount and the percentages of the pollens most often trapped by the two collectors were compared by Student's t-test for paired samples. The Partrap FA52 showed a highly significant efficacy, quite comparable to that of the Burkard device, in pollen trapping for both the total number (P < 0.0001) and the percentages of Parietaria (P < 0.0001), pine (P < 0.002), and grass (P < 0.0001) pollens. Therefore, Partrap FA52 proved to be highly effective in obtaining quantitative and qualitative aerobiologic samples in comparison with the commonly used fixed samplers.     

Thinking style,browsing primes and hypermedia navigation

There is a common assumption that hypermedia navigation is influenced by a learner’s style of thinking, so people who are inclined to apply sequential and analytical strategies (left-thinkers) are thought to browse hypermedia in a linear way, whereas those who prefer holistic and intuitive strategies (right-thinkers) tend towards non-linear paths. An experiment was conducted to study both the effects of students’ style of thinking on hypermedia navigation and the effects of primes aimed at inducing them to browse the hypermedia according to a given strategy. Two hundred undergraduates in different faculties were asked to visit a website. Navigation was preceded by some initial tasks (primes) that activated either the left- or the right-thinking style; 50 men and 50 women were randomly assigned to each of the two kinds of primes. Then participants were free to browse the hypermedia and navigational paths were tracked down. When navigation had been completed, a questionnaire measuring a preference for either the left- or the right-thinking style was filled out by participants. Analyses showed that primes influenced hypermedia navigation, leading participants to apply strategies consistent with the initial tasks. The participants’ age and faculty did not influence their behaviour in navigation. Gender and frequency of computer use determined some minor differences in hypermedia browsing, whereas there was no evidence of any relationship between thinking style and behaviour in navigation.