Search results for "Stability"
showing 10 items of 3085 documents
Probability Distribution of the Residence Times in Periodically Fluctuating Metastable Systems
1998
We investigate experimentally and numerically the probability distribution of the residence times in periodically fluctuating metastable systems. The experiments are performed in a physical metastable system which is the series of a biasing resistor with a tunnel diode in parallel to a capacitor. The numerical simulations are performed in an overdamped model system with a time-dependent potential. We investigate both the cases where the system is deterministically overall-stable and overall-unstable. In the overall-unstable regime, the experimental and the numerically investigated systems show noise enhanced stability in the presence of a finite amount of noise. The determined P(T) is mult…
Input-output finite-time stability of positive switched linear systems with state delays
2013
This paper is concerned with the problem of input-output finite-time stability (IO-FTS) for a class of discrete-time positive switched systems with time-varying delays. Two sufficient conditions for the existence of IO-FTS of such systems with respect to two different input signals are presented, respectively. All the results obtained are formulated in a set of linear inequalities. Two numerical examples are given to illustrate the effectiveness of the proposed results.
Induced &#x2113;<inf>2</inf> control of discrete-time Takagi-Sugeno fuzzy systems with time-varying delays via dynamic output feedback
2012
This paper is concerned with analyzing a novel model transformation of discrete-time Takagi-Sugeno (T-S) fuzzy systems with time-varying delays and applying it to dynamic output feedback (DOF) controller design. A new auxiliary model is proposed by employing a new approximation for time-varying delay state, and then delay partitioning method is used to analyze the scaled small gain of this auxiliary model. A sufficient condition on discrete-time T-S fuzzy systems with time-varying delays, which guarantees the corresponding closed-loop system to be asymptotically stable and has an induced l 2 disturbance attenuation performance, is derived by employing the scaled small gain theorem. Then the…
Stability of the performance of thin film modules during one year of operation
2012
At the University of Agder in Grimstad, Southern Norway, a test bench for photovoltaic modules is in operation since December 2010. Currently, various c-Si as well as aSi, CIS and HIT modules are under investigation. This project is part of the Norwegian contribution to IEA PVPS Task13. The paper focuses on the stability of the modules' MPP-performance in the course of one year. For this purpose, data on the DC response are logged together with irradiance and module temperature at one-minute intervals. Data analysis is performed in monthly blocks. The modeling involves two steps. First, the short-circuit current is expressed as function of irradiance and module temperature. Then, the MPP po…
Microbiological and physicochemical profile of sugar added ewe’s Ricotta during storage
2022
The microbiological and physicochemical traits of fresh ewe’s Ricotta made with (40% w/w) and without sucrose were investigated. Sugar added Ricotta (SAR) andcontrol Ricotta (CTR) were packaged and stored at 4°C for 90 d. Salmonella spp., Listeria monocytogenes,Escherichia coli, coagulase positive staphylococci, Enterobacteriaceae, total coliforms, Pseudomonas, yeasts, moulds and clostridia were undetectable during the entire monitoring. Total mesophilic and psychrotrophic microorganisms and mesophilic cocci lactic acid bacteria increased over time,but their development was limited in SAR production. The acidificationwas observed only for CTR. Water activity was consistently low(0.897 on av…
Effects of feeding diets supplemented with fungus myceliated grains on some production, health and oxidation traits of dairy ewes.
2017
The beneficial properties of mushrooms bioactive compounds indicate their potential use as performance enhancing natural additive for livestock animals. This paper reports the preliminary results of a research on the effects of diets supplemented with fungus myceliated grains (FMG) to lactating ewes in terms of intestinal parasites control, milk production and cheese oxidative stability. During 8 weeks, 21 ewes were divided into 3 groups fed with hay ad libitum and 1.3 kg/day per head of one of 3 concentrates with 0, 10 or 20% of FMG. In front of analogous DM and nutrients intake, the ewes fed FMG at higher levels showed a reduction of intestinal parasite infection, a tendency to improve mi…
Steady-state assemblages in a Mediterranean hypertrophic reservoir. The role of Microcystis ecomorphological variability in maintaining an apparent e…
2003
Lake Arancio is a hypertrophicMediterranean man-made lake, located on the southern coast of Sicily. Its artificial origin and the climate make it a very dynamic environment, strongly characterised by very wide water-level fluctuations. These vertical water movements interfere with the thermal stability of the water body often causing the breaking of the thermocline in mid-summer. In addition, the summer level-decrease influences the nutrient dynamics and modifies the zmix/zeu ratio. All these modifications were observed to support a high environmental variability, which was reflected by the richness of its phytoplankton composition and by its dynamics. Nevertheless, an investigation carried…
Fifteen years’ experience treating cells with inorganic arsenic, a molecule able to induce genetic / genomic instability and epigenetic changes even …
2016
Treating V79-Cl3 cells with 10 µM sodium arsenite (SA) for 24h we observed severe alterations in spindle morphology and aneuploidy; treating rat astrocytes with SA we detected HSP70 induction and DNA damage. We assumed that SA induced in dividing cells early genetic instability. Subsequently, we in vitro stabilized those V79-Cl3 cells dividing at the end of SA-treatment and maintained for long without SA (ASO cells). In ASO cells, we observed chromosomal rearrangements, increased spontaneous mutations, genome-wide DNA hypomethylation (GWDH), similarly to exposed cells. We inferred that a short-term SA exposure has long-term effects and that GWDH enhances the genetic instability. Consequentl…
Persistent genomic instability by arsenic exposure in V79 Chinese hamster cells
2006
Previously, we demonstrated that acute treatment with arsenic leads mammalian cells to exhibit persistent chromosomal instability and DNA hypomethylation, by performing investigations after about 2 months of subculturing. In order to evaluate quantitatively the continuing instability during the expanded growth, we carried out cytogenetic, morphologic and molecular analyses immediately after exposure and every week up to 112 cell generations. Briefly, V79 Chinese hamster cells were treated with 10 µM sodium arsenite (SA) for 24h; at the end of exposure, mitotic rounded-up cells were harvested by shake-off and allowed to grow in drug-free medium. The instability markers, micronucleated and mu…
Persistent dysregulation of DNA methylation in cells with arsenic-induced genomic instability
2009
The mechanisms by which arsenic-induced genomic instability is initiated and maintained are poorly understood. In previous studies long-term progression of chromosomal instability was typified by increasing aneuploidy in Chinese hamster V79 and human keratinocyte cells treated with arsenite for a 24 hr exposure period followed by growth in arsenic-free medium for 40-120 cell generations. In the current study the role of progressive DNA methylation changes was evaluated in long-term cell cultures after brief arsenite treatments as above. We have found altered genomic methylation patterns in cells that were briefly exposed to arsenic with evidence for widespread dysregulation of CpG methylati…