Прогнозирование и вероятностная оценка долговечности технических объектов

На основе методологии марковского анализа надежности предложен вероятностный подход к прогнозированию и оценке долговечности технических объектов. Разработана математическая модель прогнозирования долговечности с использованием статистических данных, характеризующих начальное и конечное распределение продолжительности срока службы технических объектов.На основі методології марківського аналізу надійності запропоновано ймовірнісний підхід до прогнозування та оцінки довговічності технічних об’єктів. Розроблено математичну модель прогнозування довговічності з використанням статистичних даних, що характеризують початковий та кінцевий розподіл тривалості терміну служби технічних об’єктів.Based on the methodology of the Markov analysis, a probabilistic approach to forecast and estimation of the longevity of technical objects is offered. A mathematical model of the longevity forecast is developed with the use of statistical data characterizing the initial and final distribution of the service term of technical objects

A palaeoenvironmental reconstruction of the Middle Jurassic of Sardinia (Italy) based on integrated palaeobotanical, palynological and lithofacies data assessment

During the Jurassic, Sardinia was close to continental Europe. Emerged lands started from a single island forming in time a progressively sinking archipelago. This complex palaeogeographic situation gave origin to a diverse landscape with a variety of habitats. Collection- and literature-based palaeobotanical, palynological and lithofacies studies were carried out on the Genna Selole Formation for palaeoenvironmental interpretations. They evidence a generally warm and humid climate, affected occasionally by drier periods. Several distinct ecosystems can be discerned in this climate, including alluvial fans with braided streams (Laconi-Gadoni lithofacies), paralic swamps and coasts (Nurri-Escalaplano lithofacies), and lagoons and shallow marine environments (Ussassai-Perdasdefogu lithofacies). The non-marine environments were covered by extensive lowland and a reduced coastal and tidally influenced environment. Both the river and the upland/hinterland environments are of limited impact for the reconstruction. The difference between the composition of the palynological and palaeobotanical associations evidence the discrepancies obtained using only one of those proxies. The macroremains reflect the local palaeoenvironments better, although subjected to a transport bias (e.g. missing upland elements and delicate organs), whereas the palynomorphs permit to reconstruct the regional palaeoclimate. Considering that the flora of Sardinia is the southernmost of all Middle Jurassic European floras, this multidisciplinary study increases our understanding of the terrestrial environments during that period of time

Androstrobus major, a new male Cycad cone from the Jurassic of Yorkshire (England)

A new Androstrobus from the Jurassic of Yorkshire is described and compared with other, earlier identified, Androstrobus species

In situ Gymnosperm pollen from the Middle Jurassic of Yorkshire

In this paper the morphology of pollen grains yielded by male Gymnosperm fructifications from the Jurassic flora of Yorkshire is studied and discussed. Several new male fructifications were found and described: Hastystrobus gen. nov. was erected for male cones yielding the Eucommiidites type of pollen grains. This genus is monotypic and the type species Hastystrobus muirii yielded pollen grains that agree with Eucommiidites troedssonii. Hastystrobus muirii very probably has Cycadalean affinities, because the whole abaxial surface of the microsporophylls is covered with sporangia. For the first time the male fructification of Ginkgo huttoni (Heer) Sternberg is described. It resembles in general the male fructification of the recent Ginkgo biloba L., and the pollen grains agree with those of Ginkgo biloba. Male cones associated with Brachyphyllum crucis Kendall have been found and described. They yielded pollen grains that after short maceration were identifiable as Circulina, while after prolonged maceration they could be assigned to Classopollis multistriatus Burger. Brachyphyllum crucis is provisionally assigned to the Hirmerella-group on the basis of its male cone and pollen grains. The cones were compared with other male cones containing Classopollis pollen, which were also attributed to the Hirmerella-group. It is suggested that all members of the Hirmerella-group have an epidermis with a special type of stoma. Masculostrobus harrisii sp. nov. is described. This male cone resembles closely the male cone of Elatides williamsoni (Brgt) Sew., but its pollen grains are of the Inaperturopollenites-type, instead of the Perinopollenites-type. The new species Pityanthus scalbiensis yielding bisaccate pollen grains of a rather primitive type is described; there is almost no saccus infrastructure present. The Czekanowskia-group (including Leptostrobus and Solenites) in all probability does not belong to the Ginkgoales but to the Conifers. An interesting find was that the pollen grains of the Araucariaceous Brachyphyllum mamillare Brgt are of two types: In type 1 the nexine and sexine are attached to each other, while in type 2 the nexine is loose from the sexine and is somewhat shrunk. In the latter type also pollen grains were found that are somewhat trilobate. A similar dimorphism of pollen grains was also found in the recent Araucaria araucana (Molina) K. Koch. The pollen grains from the various male fructifications were compared with those from other male fructifications related to them. If the cones were assigned to recent taxa, the pollen grains were compared with recent pollen grains from those taxa (Cycadales, Ginkgoales and Coniferospermae). The pollen grains were also compared with dispersed pollen grains, mainly from the Jurassic

The Early Jurassic male ginkgoalean inflorescence Stachyopitys preslii Schenk and its in situ pollen

An early Liassic male inflorescence of Stachyopitys preslii with in situ pollen is described from a clay lens in the sandpit Küfner near Pechgraben, Bavaria, Germany. These male inflorescences have been known since the 19th century and are rather common in the early Liassic floras of Bavaria, but in situ pollen was hitherto unknown. Stachyopitys preslii is always found in association with the leaves and the female fructifications of Schmeissneria microstachys. The in situ pollen proved to be monosulcate, a pollen type commonly occurring in the Cycadophyta and Ginkgophyta. This strengthens the possible attribution of the parent plant of S. preslii (Schmeissneria microstachys) to the Ginkgoales

Some additional notes on male Gymnosperm fructifications from the Jurassic Flora of Yorkshire

This paper is an addendum to the author’s (1971) paper. At the time that the latter paper was finished, there were difficulties in taking photographs of the newly described male fructifications. Subsequently those difficulties have been solved, and the present paper contains the photographs of the male fructifications of the type specimens of Hastystrobus muirii v. Kon., Masculostrobus harrisii v. Kon., and Pityanthus scalbiensis v. Kon., and the photographs of the male fructifications, as described in the above-mentioned paper, of Ginkgo huttoni (Heer) Sternberg and Brachyphyllum crucis Kendall. All specimens are preserved in the Division of Palaeobotany and Palynology, Botanical Museum and Herbarium, State University, Utrecht, The Netherlands. Most of the photographs were taken with the specimens illuminated obliquely in air, but some were taken with the specimens flooded with oil. This procedure is generally applied when the specimen requires enhancement of contrast, so that details are more evident than if the specimen was photographed dry

Rare conifers from the type area of the Maastrichtian (Upper Cretaceous, southeast Netherlands)

Two conifer twigs from the type area of the Maastrichtian are described as Brachyphyllum sp. 1 and Brachyphyllum sp. 2. They might belong to the Cheirolepidiaceae, Podocarpaceae or Taxodiaceae. Brachyphyllum sp. 1 occurs with the conifers Brachyphyllum patens (?Cheirolepidiaceae) and Elatidopsis cryptomerioides (Taxodiaceae), the seagrass Thalassocharis bosqueti and the ammonite Baculites vertebralis in the upper part of the Kunrade Chalk in the Kunrade area, while Brachyphyllum sp. 2 probably originates from the lower part of this deposit

A Rhaeto-Liassic flora from Airel, Northern France

An assemblage of fossil plants from the Upper Triassic/Liassic of Airel (Manche), Northern France, is recorded, and two new species, Hirmerella airelensis sp. nov. and Classopollis harrisii sp. nov., are described and figured. In situ and dispersed pollen is compared and a lycopod megaspore and microspore described. The assemblage is compared with others from France and Wales