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Asociația Ad Astra a anunțat câștigătorii Premiilor Ad Astra 2022: http://premii.ad-astra.ro/. Proiectul și-a propus identificarea și popularizarea modelelor de succes, a rezultatelor excepționale ale cercetătorilor români din țară și din afara ei.
Publicatii proprii
A New Denoising System for SONAR Images
The SONAR images are perturbed by speckle noise. The use of speckle reduction filters is necessary to optimize the image exploitation procedures. This paper presents a new denoising method in the wavelet domain, which tends to reduce the speckle, preserving the structural features and textural information of the scene. Shift-invariance associated with good directional selectivity is important for the use of a wavelet transform (WT) in many fields
Read moreOn the statistical decorrelation of the wavelet packet coefficients of a band-limited wide-sense stationary random process
This paper is a contribution to the analysis of the statistical correlation of the wavelet packet coefficients resulting from the decomposition of a random process, stationary in the wide-sense, whose power spectral density (PSD) is bounded with support in [-pi, pi]. Consider two quadrature mirror filters (QMF) that depend on a parameter r, such that these filters tend almost everywhere to the Shannon QMF when r increases. The parameter r is called
Read moreDescription of a new species of Dipara Walker (Hymenoptera: Pteromalidae) from Hungary
A new species of the genus Dipara WALKER, 1833, Dipara alata sp. n., from Hungary is described. Diagnosis, synonymy and a short review of valid Dipara species are given.
Read morePopulation size effects on the behaviour of Libellula fulva (Odonata: Libellulidae) males, a five year study
We tested the hypothesis that population density alters male territorial and mating behaviour of dragonflies. We predicted that males at higher densities fight more and mate less. During five years we studied two Libellula fulva populations along two small lowland creeks in East Hungary. Using mark-resight method we marked a total number of 1454 dragonfly males. Our results show that on the two study sites there were different population densities.
Read moreOptimal clutch size of the gall wasp Diplolepis rosae (Hymenoptera: Cynipidae)
Clutch size of the gall wasp Diplolepis rosae was studied in galls on Rosa spp. in Eastern Hungary and Romania, Transylvania on four dry pastures.We hypothesised that there was an optimal clutch size, and it was controlled by the emerging rate of the gall inducer and the escaping failure of hatched adults. The most frequent clutch size was 25–30 chambers, and there was a second peak around 60 chambers in each frequency distribution. The most common
Read moreInquiline effects on a multilocular gall community
The influence of inquiline on the gall of Diplolepis rosae (Hymenoptera: Cynipidae) and its community was investigated. It is expectable that inquilines should cause major changes in the gall-community. Evidences for inquiline effect on multilocular galls are provided and the result suggests that the outcome shows similarity with unilocular ones. Gall size, number of emerged individuals and diversity increased significantly for inquilined galls.
Read moreHigh host plant aggregation involves uniform gall distribution and high prevalence: the case of wild roses and Bedeguar gall wasps (Diplolepis rosae)
We studied the effect of rose shrub spatial pattern and density toward its parasitism by Diplolepis rosae gall wasps, considering host shrubs’ size. There were eight sample sites on dry pastures and/or on the edges of these pastures. Our results show that high densities rose shrubs show uniform distribution, while the low densities ones appear aggregated. Gall density and prevalence are affected by host plant aggregation. Gall aggregation is inversely
Read moreParasitoids of the Bedeguar gall (Diplolepis rosae): effect of host scale on density and prevalence
Host plants have significant effects on parasitoid and herbivore distribution. There are just a few reports on tritrophic interactions. We aimed to study the relationships between rose host shrub and Bedeguar gall density with special attention to densities and prevalence of parasitoids at two scales: host shrub and gall. We found that gall density was inversely density dependent of shrub density. Parasitoid density was density dependent of both
Read moreSpectral combination of ultrashort laser pulses
An ultrashort and ultraintense pulses combination method is proposed, based on the spectral combination of parallel laser pulses, with complementary spectra, in chirped pulse amplification (CPA) laser systems. In a proof-of-principle experiment, it is demonstrated that two long pulses of 330 fs can be overlapped in a collinear way, to produce a shorter pulse, of 190 fs. As a consequence, it is shown that the power for the combined pulse obtained
Read moreSurface water pollution generated by mining activities. Case Study: Aries River middle catchment basin, RomaniaA
The Arieş River, due to its geographic position and its significance in the Mureş – Tisza Basin, has a major impact on environmental media, influencing their quality. In the Middle Catchment Basin the main industrial activity is mining, since the Roman times, when the first mines were opened. The mining operations in the region generated a severe pollution of all the environmental media. The paper identifies the risk areas in the middle Aries
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