Search results for " disturbance"
showing 10 items of 133 documents
A stochastic model of seed dispersal pattern to assess seed predation by ants in annual dry grasslands
2005
A combined field experiment and modelling approach has been used to provide evidence that ants may be responsible for an observed lower patchiness and higher plant diversity in the neighbourhood of ant nests, within Mediterranean dry grasslands belonging to the phytosociological class Tuberarietea guttatae. The hypothesis was that seeds occurring in clumps may have an higher probability to be harvested than seeds having a scattered distribution. In order to test this hypothesis, four analysis steps have been performed. First, the seed productivity and dispersal pattern was recorded for four plant species found, either more abundant beside the ant nests (Tuberaria guttata, Euphorbia exigua) …
Robust Active Disturbance Rejection Control of Induction Motor Systems Based on Additional Sliding-Mode Component
2017
This paper deals with motion control systems with induction motor, subject to severe requirements on both dynamics and steady-state behavior. The proposed control methodology could be viewed as an advancement of the standard field oriented control. It consists of two control loops, i.e., the rotor flux and the speed control loops, designed using the active disturbance rejection control method, with the aim to cope with both exogenous and endogenous disturbances, which are estimated by means of two linear extended state observers and then compensated. Moreover, with the aim of achieving total robustness, a sliding-mode based component is designed, in order to take into account disturbance es…
Alteraciones del sueño producidas por el ruido ambiental*
1989
ResumenEste articulo presenta los resultados de una encuesta realizada con el objetivo de valorar distintos aspectos relacionados con el ruido ambiental y sus efectos sobre determinadas comunidades urbanas. Un total de 263 residentes en 5 emplazamientos diferentes de la ciudad de Valencia fueron entrevistados. En estos 5 emplazamientos se realizaron de manera independiente una serie de medidas de los niveles de ruido durante las 24 horas del dia y en distintos días de la semana.:El 400%0 de los encuestados manifestó tener alguna dificultad para dormirse y el 59% de ellos lo atribuyó al ruido causado por el tráfico. Asimismo, un 49% de los encuestados declaró despertarse durante la noche (el…
H∞ fuzzy control of DC-DC converters with input constraint
2012
Published version of an article in the journal: Mathematical Problems in Engineering. Also available from the publisher at: http://dx.doi.org/10.1155/2012/973082 Open access This paper proposes a method for designing H∞ fuzzy control of DC-DC converters under actuator saturation. Because linear control design methods do not take into account the nonlinearity of the system, a T-S fuzzy model and a controller design approach is used. The designed control not only handles the external disturbance but also the saturation of duty cycle. The input constraint is first transformed into a symmetric saturation which is represented by a polytopic model. Stabilization conditions for the H∞ state feedba…
Robust control of stochastic systems against bounded disturbances with application to flight control
2014
This paper investigates the problems of state observer design and observer-based integral sliding-mode control (SMC) for a class of Itô stochastic systems subject to simultaneous input and output disturbances. A new type of sliding-mode-based descriptor observer method is developed to approximate the system state and disturbance vectors. An integral-type SMC scheme is proposed based on the state estimation to stabilize the overall system. The main contributions of this approach are as follows: 1) The desired estimations of state and disturbance vectors can be obtained simultaneously, and 2) in the designed sliding-mode observer, the integral term of the Itô stochastic noise is eliminated …
Immunity of a Virtual Instrument to conducted electromagnetic disturbances
2004
In the paper the performances of the Virtual Instruments under conducted electromagnetic disturbances are investigated, in order to find out if and how their metrological characteristics change with respect to the ones measured in absence of electromagnetic threats. The analysis is carried out by means of experimental tests, subjecting the AC power port of the systems under test to the conducted disturbances considered by the IEC-61326 standard and following the test procedures prescribed in the IEC-61000-4-series standards. The results show that the tested measurements instruments are sufficiently immune to these disturbances, since no variations of the distinctive parameters have been obs…
A Phase-Locked Loop for the Synchronization of Power Quality Instruments in the Presence of Stationary and Transient Disturbances
2007
Power quality instrumentation requires accurate fundamental frequency estimation and signal synchronization, even in the presence of both stationary and transient disturbances. In this paper, the authors present a synchronization technique for power quality instruments based on a single-phase software phase-locked loop (PLL), which is able to perform the synchronization, even in the presence of such disturbances. Moreover, PLL is able to detect the occurrence of a transient disturbance. To evaluate if and how the synchronization technique is adversely affected by the application of stationary and transient disturbing influences, appropriate testing conditions have been developed, taking int…
Fire in Protected Areas - the Effect of Protection and Importance of Fire Management
2012
Fires are important but socially and economically unwanted disturbances of the ecosystems. They cannot be considered as a problem, they are global phenomena. Protected areas are created to protect biodiversity, and strict protection is often applied, forgetting that fire had shaped that that we aim to protect. This harsh protection is producing important changes in the protected habitats and is increasing their vulnerability to destructive wildfires. Thus, it is of major interest to incorporate fire management in the protected areas plan, including the (re)use of prescribed fire and traditional burning in order to reintroduce fire regimens, fundamental to the landscape sustainability. This …
A Rare Case of Docetaxel-Induced Hydrocephalus Presenting with Gait Disturbances Mimicking and Coexisting with Taxane-Associated Polyneuropathy: The …
2017
Docetaxel constitutes a widely used chemotherapeutic agent as a first-line treatment for several neoplastic diseases. One of the most common side effects induced by this drug is polyneuropathy, which among other symptoms can cause gait disbalance. However, in exceptional cases gait disturbances could be related to docetaxel-induced hydrocephalus, a rare event that up to the present has been overseen throughout the medical literature and should be meticulously differentiated from polyneuropathy, since its clinical features, treatment, and prognosis differ drastically. We present the case of a woman with a progressive gait disturbance that started immediately after having been treated with do…
Menstruation: science and society
2020
© 2020 The Authors Women's health concerns are generally underrepresented in basic and translational research, but reproductive health in particular has been hampered by a lack of understanding of basic uterine and menstrual physiology. Menstrual health is an integral part of overall health because between menarche and menopause, most women menstruate. Yet for tens of millions of women around the world, menstruation regularly and often catastrophically disrupts their physical, mental, and social well-being. Enhancing our understanding of the underlying phenomena involved in menstruation, abnormal uterine bleeding, and other menstruation-related disorders will move us closer to the goal of p…