Search results for "Disturbance"

Load frequency regulation using observer based non-linear sliding mode control

2019

Abstract In this paper, the generalized extended state observer (GESO) and non-linear sliding mode control (SMC) are merged together to study the frequency deviation problem in multi-area power system. In study, the GESO is used not only for state and disturbance estimation but also for disturbance rejection of the system. The said observer ensures accurate estimation of the actual states leading to convergence of estimation error to zero. The non-linear SMC is used to increase the damping ratio of the system whenever, any perturbations occurs. The proposed observer based controller is compared with an existing two-layer active disturbance rejection control (ADRC) and also validated on larg…

Observations of Forbush Decreases of cosmic ray electrons and positrons with the Dark Matter Particle Explorer

2021

The Forbush Decrease (FD) represents the rapid decrease of the intensities of charged particles accompanied with the coronal mass ejections (CMEs) or high-speed streams from coronal holes. It has been mainly explored with ground-based neutron monitors network which indirectly measure the integrated intensities of all species of cosmic rays by counting secondary neutrons produced from interaction between atmosphere atoms and cosmic rays. The space-based experiments can resolve the species of particles but the energy ranges are limited by the relative small acceptances except for the most abundant particles like protons and helium. Therefore, the FD of cosmic ray electrons and positrons have …

Community composition of soil microarthropods of acid forest soils as affected by wood ash application

2002

Summary The responses of soil microarthropod communities of acid forest soils to wood ash-application was studied both in a sixty years old pine forest stand (wood ash dose: 3000kg ha —1 ) and in laboratory microcosms (wood ash dose: 5000kg ha —1 ). We also tested whether microarthropod communities stressed with wood ash were more sensitive to an additional disturbance, drought, than the microarthropod communities in the ash-free soil. Microarthropods were sampled five times during the field experiment and four times during the laboratory experiment. At each sampling the abundance and community structure of microarthropods were analysed. In the field the number of collembolans, and in the l…

Effects of Canopy Gap Disturbance on Forest Birds in Boreal Forests

2013

We studied the effects of small-scale disturbance on breeding, forest passerine birds in an old-growth and managed boreal forests in northern Finland. Small-scale disturbance (< 2 ha) in an old-growth and managed forests originated from wind falls and small clear cuts. Continuous forest without gaps was used as a control for both management types (old-growth and managed forests). Passerines' response to disturbance was examined by estimating species richness and abundance of different ecological groups. Species richness and the total abundance of birds did not differ between gap and non-gap plots, neither did the abundance of most ecological groups. Management type or study year were the mo…

Emotional deficit as a neuropsychopathological disturbance in HIV infection

2001

We have been very interested in the article of Castellon et al. (2000) on the neuropsychiatric disturbances present in HIV-infection, which reports results very congruent with those published previously by our research group. Indeed, for many years we have studied psychopathological perturbations (depression and anxiety) as well as more specific emotional dimensions like emotional deficit and loss of control in HIV positive patients.

Short-term recovery of benthos following disturbance from stream habitat rehabilitation

1994

The recovery of benthic macroinvertebrates after disturbance from stream rehabilitation was studied in the River Livojoki, northern Finland. The stream that had been channelized for log transport was rehabilitated on 1 July 1992 by digging holes and inserting boulders. We measured habitat characteristics and sampled benthic animals before and after rehabilitation, including an unrehabilitated control site. The immediate effect of rehabilitation was a slight decrease in the abundances of benthic insects. Recolonization occurred rapidly, within 10 days. Disturbance of the rehabilitation did not have a detectable effect on the macroinvertebrate community. Most species-level changes and communi…

19th Meeting of the Italian Primatological Association

2009

Histopathological progression of hidradenitis suppurativa/acne inversa

2021

It is generally acknowledged that the first morphological change of hidradenitis suppurativa/acne inversa (HS/AI) consists of infundibular plugging of the folliculosebaceous apocrine apparatus, which is followed by acute and chronic inflammation, cysts with sinus formation, and fibrosis. Alternatively, it has been hypothesized that HS/AI is primarily a neutrophilic autoinflammatory disease and that the follicular plugging typical of this disease is secondary to inflammation.To review the sequence of the changes that mark the disease development, we have performed a histopathologic study on the surgical material from a series of axillary and inguinal/perineal cases.The histologic material fr…

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) …

Emulating natural disturbances in boreal Norway spruce forests: Effects on ground beetles (Coleoptera, Carabidae)

2014

The disturbance regime of boreal forests has been substantially altered by human influence in northern Europe. In this context, emulations of natural disturbance have become increasingly common as management tools to minimize negative effects of forestry on biodiversity. In a large-scale habitat-restoration experiment conducted in Norway spruce stands in southern Finland, we tested the effects of controlled burning, partial harvesting, and increasing the amount of downed wood on ground beetles (carabids). We also evaluated the effects of moisture gradients within harvested sites. We collected beetles seven years after the treatments. The moisture gradient was the strongest determinant of ca…