Interior Of Valve Research Articles

Measurement of cryogenic valve straightness without accessing valve exterior

The work presents a method of noninvasive measurement of long-stem cryogenic valve straightness, using simple and generally available means. The method does not require an access to valve exterior, what is a common requirement in practice, where such access is impossible in case of helium cryogenic valves confined in all-welded valve boxes. Valve’s deflection is computed using computer vision algorithms (Hough transform for circles), based on photographs of valve interior. Results obtained by the method have been validated using reference data from a validation test stand with a ruler for deflection measurement. The method may be applied for a more general case, namely to measure deflections of pipes ended with sleeves with diameters smaller than the pipe’s diameter.

Valve ultrastructure of Rhopalodia constricta (W.Smith) Krammer (Rhopalodiales, Bacillariophyceae) and a consideration of its systematic placement

Light microscope (LM) observations of specimens of Rhopalodia constricta (W.Smith) Krammer are made from the holotype slide. LM and scanning electron microscope (SEM) observations from Rabenhorst’s material of this species are also presented. The two populations are similar in size and ornamentation. Many features seen in the SEM are presented here for the first time, including documentation of the valve interior and the girdle bands. A flap from the valvocopula extends onto the valve exterior at the apices and covers the raphe end-this is the first time this feature has been documented in the Rhopalodiales. Rhopalodia constricta is compared and contrasted with other, small species of the genus. It lacks features seen in the generitype, R. gibba, suggesting it might be phylogenetically dissimilar to the type species of the genus.

NEW BIOCLAUSTRATION OF A SYMBIONT IN THE MANTLE CAVITY OF CLITAMBONITES SCHMIDTI (BRACHIOPODA) FROM THE SANDBIAN (UPPER ORDOVICIAN) OF ESTONIA

Abstract A new bioclaustration of a symbiont is here described from the mantle cavity of the strophomenatan brachiopod Clitambonites schmidti. It is the second bioclaustration in brachiopods known from the Kukruse Regional Stage (Sandbian) of Estonia. It shares affinities with the bioclaustrations Burrinjuckia and Haplorygma. The outgrowth in the ventral valve interior was secreted by the brachiopod around a symbiont. Most likely the symbiont was a suspension feeder that collected food particles from the brachiopod's mantle cavity. The symbiont was either a kleptoparasite or fed on the brachiopod's feces (coprophagy). The majority of symbiosis cases in brachiopods in the Ordovician of Baltica involve clitambonitids as the hosts. Thus, clitambonitid brachiopods were more likely hosts for symbiosis than other brachiopods in the Ordovician of Baltica.

Analysis on flow induced vibration of main steam bypass valve in a nuclear power plant

Based on the fact that the main steam bypass system of a nuclear power plant vibrates violently during operation, the failure of couplings and other parts of the bypass valve occurs many times, which seriously affects the safe operation of the unit. According to bypass discharge system, and the bypass valve related drawings bypass valve fluid dynamics model is established, on the opening of the bypass valve interior flow field in CFD numerical simulation analysis, combining with the field vibration test results, for the opening of the bypass valve interior flow field in CFD numerical simulation analysis and vibration mechanism research, found that the structure of the piping system vibration and vortex shedding in the valve to inspire the chattering of the valve stem and even the axis of the main causes of fracture and valve is the high degrees of vortex-induced resonance is the main reason of the turbulent flow hood.

Frustulia tunariensis sp. nov. (Bacillariophyceae) from the Andes of Bolivia, South America

Frustulia tunariensis sp. nov. is originated from a high-altitude peatland in the Tunari Cordillera, a branch of the Andean range in Bolivia. The new taxon is distinguished by the thick longitudinal ribs, the globose polar nodule with faint helictoglossa that does not produce an apical extension, and by the high areola and stria density, not found in any of the morphologically closely related taxa. Features of the folded valvocopula, such as the presence of a siliceous membrane as pars interior, and poroids present in the tube-like portion opening as slits to the valve interior and as a single row of poroids to the exterior, are also unique characters in the new taxon. Based on a literature review, a comparison of the newly proposed species with morphologically similar taxa was made. Also, published information shows the potential of girdle bands to distinguish groups of species and species themselves within Frustulia. Likewise, remarks on the ecological and distribution aspects of Frustulia in the Bolivian Altiplano are included, focusing on taxonomic quality, geographic coverage and sampling, and potential to represent the genus in the high Bolivian Andean plateau.

Catenula exigua sp. nov., a new marine diatom (Bacillariophyta) species from the Adriatic Sea

During a survey of the epizoic diatom flora on carapaces of loggerhead sea turtles (Caretta caretta) from the Adriatic Sea, a relatively small population of an unknown amphoroid species was observed, presenting some morphological similarities with the genera Lunella and Catenula. Due to the small size and the lack of distinct structures visible in LM, the observations of its ultrastructure under very high magnification in the scanning electron microscopy (SEM) proved to be critical in taxon delineation and indicated that it should be separated as a new Catenula species. The new species is characterized by very small, dorsiventral valves, striae composed of 1–3 small, marginally placed areolae, a very simple raphe structure lacking terminal raphe fissures, straight simple central raphe endings, the absence of helictoglossa and a distinct central nodule, the latter often discernible in LM. Typical ghost striae, reported to be one of the main morphological features of the genus Catenula, are very faintly present and only visible in the valve interior. The new species is illustrated using both LM and SEM observations and compared with all other known Catenula and Lunella species.

Morphology and molecular phylogeny of Gomphonemopsis sieminskae sp. nov. isolated from brackish waters of the East China Sea coast

AbstractWe describe the new species Gomphonemopsis sieminskae from brackish waters of the East China Sea littoral near Ningbo, China. Two diatom strains isolated from Ulva sp. were successfully grown, then analyzed by light (LM) and scanning electron (SEM) microscopy. The new species is compared to known Gomphonemopsis species, and similarities to G. pseudoexigua and G. obscurum are emphasized. Although the size metric data overlap and the external views are fairly similar, the two taxa differ in their valve interior. Molecular barcoding strongly discriminated G. sieminskae from G. cf. exigua, while rbcL gene-based phylogeny showed G. sieminskae to be sister to Phaeodactylum tricornutum. In this respect our results confirm the recent discovery, based on molecular data, that Gomphonemopsis is a close-relative taxon to Phaeodactylum, and place it in Phaeodactylaceae instead of Rhoicospheniaceae as inferred solely from morphology.

Epithelial cell moulds preserved in the earliest acrotretid brachiopods from the Cambrian (Series 2) of the Three Gorges area, China

Distinctive moulds of epithelial cells are known to occur on valve interiors in early Palaeozoic acrotretid brachiopods but morphological variation and distributional patterns of the epithelial cells imprints remains poorly known. Herein, we present for the first time a detailed study of exquisitely preserved epithelial cell moulds and shell micro-structures in acid-etched material of the earliest acrotretid brachiopod Eohadrotreta zhenbaensis from the Shuijingtuo Formation (Cambrian Series 2) of Aijiahe section, approximately 25 km north-west of Yichang City, western Hubei Province. The ventral and dorsal epithelial cell moulds (on average 18 μm across) are usually isometrically convex or concave polygonal with a variable outline (tetragon, pentagon and hexagon). Investigation of the new material demonstrates that the disposition of pronounced epithelial cell pustules or depressions in shell interiors most likely is associated with regions of thickened muscle attachments in ventral and dorsal valves – a character that potentially could be of use in taxonomy, though detailed comparative studies of such epithelial microstructures of acrotretids and other brachiopod taxa remain to be done.

<span lang="EN-US">Entogoniopsis</span><span lang="EN-US"> gen. nov. and Trilamina gen. nov. (Bacillariophyta): a survey of multipolar pseudocellate diatoms with internal costae, including comments on the genus Sheshukovia Gleser</span>

We present the results of an extensive light-(LM) and scanning electron microscope (SEM) study of internally costate pseudocellate multipolar diatoms previously placed within Biddulphia, Entogonia, Sheshukovia and Triceratium. For the first time, we critically examine the poorly known genus Sheshukovia. We find that the separation of Sheshukovia from Triceratium is justified, as advocated by Gleser (1975, 1984), but also show that Sheshukovia as circumscribed by Gleser (1975, 1984) is a heterogenous taxon comprising at least three morphologically distinct groups. In order to clarify the confused taxonomy of pseudocellate multipolar diatoms, a preliminary phylogenetic analysis is presented, including Triceratium, Sheshukovia, Entogonia, Medlinia and two new closely related genera proposed here: Entogoniopsis and Trilamina. Both new genera have valvocopulae that attach to costae on the valve interior by means of a variety of clasping devices. Entogoniopsisis is characterized by areolate valves and a twofold mechanism for valvocopula attachment, whereas Trilamina possesses extensive hyaline areas and a threefold valvocopula attachment mechanism. The twofold mechanism for valvocopula attachment in Entogoniopsis, and the threefold valvocopula attachment mechanism in Trilamina are here considered synapomorphies supporting the monophyly of the respective taxon. The morphology of 19 species, four of which are new, is documented using both LM and SEM and a further 18 taxa are transferred from elsewhere, observations being based on literature survey and/or LM examination. When original material is available, taxa are typified. Two new morphological terms are proposed: a trifolium is a triradiate raised sector located in the central part of undulate valve faces in some species of Entogoniopsis; a fossa is a circumferential invagination of the advalvar edge of the valcocopula. These features are found in both new genera proposed herein.

Numerical Simulation of Flow in Imported Steam Turbine Inlet Components with Equilibrated Holes in High Performance

The main inlet component of steam turbine is control valve. The stable operation of the steam turbine control valve is vital for safe and stable operation of the steam turbine and safety production of the power plant. However, due to the complexity of the structure and unsteady characteristics of steam flow in the valve, there is not enough experimental method about the detailed flow characteristics of the area near control valve disc and the inside of the valve chamber up to now. This article is to focus on the simulation of the steam turbine control valve interior flow field which includes the valve pre-inlet channel in different conditions, then find the reasons which caused instability and pressure loss of the control valve by analyzing the flow field details, finally further optimization design. The profile matching of the valve disc and valve seat has a great influence on the interior flow field of control valve, so analysis of the high performance valve disc shape and divergence angle of valve seat is carried out, and the research conclusion is used for guide design and development of the control valve.

Population dynamics and taphonomy of the Late Triassic (Carnian) freshwater bivalves from Krasiejów (Poland)

The Krasiejów clay pit (SW Poland) has so far been known for yielding mass accumulations of Late Triassic (Carnian) vertebrate fossils. However, unionoid bivalves occur abundantly within the 1 metre-thick shell-rich lacustrine interval at Krasiejów. They are most commonly preserved as shell imprints in the claystone or mudstone. A layer-by-layer quantitative sampling for shell external moulds was conducted directly in the bedding planes at two sites. The most numerous findings come from red and variegated layers in the upper part of this interval, which correspond to a well-aerated sediment. Single valves dominate at both sites and in all layers; valves in butterfly position are rare. The abundance of single valves throughout the sedimentation of the whole interval, both juveniles and adults, indicates that this interval represents the graveyard of a stable, reproducing population. The only exception is a bedding plane in the upper part of the lacustrine interval with numerous concretionary infills of closed valve interiors. They were presumably killed by a sudden load of sediment and, after the early diagenetic cementation was completed, they were winnowed from the mud. The mortality pattern is characterised by a high juvenile mortality (peak at about 13mm), and a slight increase in subadult mortality (peak at about 30mm; adult specimens reach 55mm). Complete lack of early juvenile shells representing the stage with prominent ornamentation may have resulted from predation rather than from size-selective post-mortem preservation. The course of ontogeny shows virtually isometric growth. The range of variability of shell proportions within and between layers suggests the succession of monospecific populations. The Krasiejów lacustrine interval represents the oldest insight into the dynamics and taphonomy of unionoid palaeocommunity.

Three new species of freshwater Diploneis from Japan

Three new Diploneis species are described from freshwater lakes in Japan. A complex wall structure is demonstrated in D. aokiensis sp. nov. and D. yamanakaensis sp. nov., where the basic alternation of transapical ribs (virgae) and striae is overlain by a system of secondary branches and struts supporting the external perforate surface. Diploneis linearifera sp. nov. possesses remarkable external slits, distributed irregularly around the margin of the valve and near the raphe. The grooves in the outer layer of the valve wall, which do not penetrate to the valve interior, have no known parallel in other diatoms but may be related to the angular holes noted previously in D. finnica (Ehrenberg) Cleve and D. marginestriata Cleve.

Optimization of a Hydraulic Damper Performance with the Use of Fluid-Structure Simulation

The aim of this paper is to develop a method for optimizing the design of a spring valve system by reducing the aeration and cavitation effect which negatively influences the performance of a shock absorber. A fluid-structure interaction (FSI) model is used in order to modify the geometry of the valve interior and, in turn, to achieve better performance in shock absorbers. The paper analyzes the pressure distribution along the flow paths inside the valve cavity to reduce the risk of aeration and cavitation, while other important engineering aspects are omitted, e.g. durability of disc-spring valve systems as discussed in [1]. The objective of this work is to show key steps of the simulation process focusing on interactions between fluid and structure domain and to review relevant simulation results.

Optimization of a Hydraulic Damper Performance with the Use of Fluid-Structure Simulation

The aim of this paper is to develop a method for optimizing the design of a spring valve system by reducing the aeration and cavitation effect which negatively influences the performance of a shock absorber. A fluid-structure interaction (FSI) model is used in order to modify the geometry of the valve interior and, in turn, to achieve better performance in shock absorbers. The paper analyzes the pressure distribution along the flow paths inside the valve cavity to reduce the risk of aeration and cavitation, while other important engineering aspects are omitted, e.g. durability of disc-spring valve systems as discussed in [1]. The objective of this work is to show key steps of the simulation process focusing on interactions between fluid and structure domain and to review relevant simulation results.

Cavernosa kapitiana (Bacillariophyceae): biogeography and morphology of the different life cycle stages

The monospecific diatom genus Cavernosa is known from only two locations: Kapiti Island off the west coast of New Zealand and Ile de la Possession, Crozet Archipelago, in the southern Indian Ocean. Cavernosa kapitiana Stidolph is a chain-forming diatom with cylindrical frustules having an elongated valve mantle. We provide a description of the different life-cycle stages (normal frustules, globular initial cells, bell-shaped initial cells, first daughter cells of initial cells) of C. kapitiana based on examination of new material from Ile de la Possession and material from the type locality on Kapiti Island. The most remarkable morphological features include the complex valve face structure composed of pores, granules and ridges, the subdivision of the valve interior into marginal caverns, the complex structure of the mantle and girdle, and the presence and morphology of rimoportulae. The study concludes with an emended species description of C. kapitiana.

POSTMORTEM ENCRUSTATION OF THE ALIEN BIVALVE ENSIS AMERICANUS (BINNEY) BY THE BARNACLE BALANUS CRENATUS BRUGIERE IN THE NORTH SEA

The alien razor shell Ensis americanus (Binney) is a common bioclast on Dutch beaches. It is uncommonly encrusted by the balanid Balanus crenatus Brugiere on both the interior and exterior surfaces of both valves. This occurs postmortem, but before the ligament breaks. A well-preserved specimen from Zandvoort is described which confirms that this pattern of skeletozoan infestation is initiated in dead shells still in the burrow, but protruding above the sediment surface. After exhumation, the recumbent shell can be further infested by subsequent balanid spatfalls. Such a pattern of encrustation is only likely in burrowing bivalves with a permanent and prominent gape to the shell.

Larval to Adult Growth Stages and Paleoenvironment of Odontogryphaea thirsae (Gabb, 1861): A Late Paleocene Oyster from the Northern Gulf Coastal Plain, U.S.A.

Abstract Assemblages of the boat-shaped bivalve Odontogryphaea thirsae (Gabb, 1861) from southwestern Alabama are used to define three ontogenetic growth stages that are bounded by major discontinuities in either mineral structure or growth-line prominence. Features of the larval and juvenile stages are described here for the first time and are compared with the well-known morphologic features that distinguish adults (late dissoconchs). The larval stage is represented by prodissoconch valves which are about 0.4 mm in height with suborbicular outlines, commarginal striations, and ridge-like, opisthogyral beaks. The juvenile (early dissoconch) stage is expressed by dissoconch valves up to 19 mm in height with elliptical outlines (height > length), indistinct commarginal growth lines, flat commissural planes, and tiny attachment areas on left valves; the valve interiors exhibit a posterior adductor muscle scar, a resilifer, and chomata. The adult (late dissoconch) stage is characterized by dissoconch valves ...

TWO NEW SPECIES OF PINNULARIA FROM GREAT XING'AN MOUNTAINS, CHINA

During an extensive survey of diatoms from the Great Xing'an Mountains, China, two unusual species of the genus Pinnularia Ehrenb. were discovered. Based on both light and scanning electron microscopic observations, both species are described as new: Pinnularia subaldenii sp. nov. and Pinnularia paludosa sp. nov. The morphology of both species is compared to other similar species of the genus. Both have no fascia in the central area. Pinnularia subaldenii is distinguished by the clearly different central area and continuous raphe on the valve interior. Pinnularia paludosa is distinguished by its large dimensions and distinct crescent-shaped markings in the central area. Environmental conditions in the habitats containing the two new species are presented and discussed.

Paleoecology of epizoans and borings on some Upper Cretaceous chalk oysters from the Gulf Coast

Analysis was made of a hard substrate fauna found on right valve interiors and exteriors of the epifaunal reclining oyster Pycnodonte mutabilis from the Maastrichtian (Navarroan) Saratoga Formation (southwestern Arkansas). Comparison of boring and encrustation patterns on both sides of valves indicates that a major portion of colonization on valve exteriors occurred while host oysters were alive. Paleoautecologic information derived from such valve exterior patterns includes evidence of rheotropic orientation by encrusting juvenile P. mutabilis and preferential location of Trypanites sp. borings in surficial shell grooves. Valve exteriors supported a hard substrate paleocommunity which had the following non-interactive progressive colonization sequence: (1) Trypanites sp. and P. mutabilis juveniles; (2) Entobia sp., serpulid worm tubes, and Bullopora sp.; and (3) cheilostome bryozoans. This sequence could have been caused by low seasonality and ranked success of colonizing encrusters and borers. Colonization of valve interiors generally differed from exteriors only in that many interiors were first colonized by the clionid sponge that created Entobia sp., which had already occupied the exterior, and which quickly bored through the valve to occupy the interior upon the host's death. □Trace fossils, epizoans, borings, Gryphaeidae, palaeoecology, communities, colonization sequence, Late Cretaceous, Maastrichtian, Navarroan, Arkansas.

A gregarious lingulid brachiopodLongtancunella chengjiangensisfrom the Lower Cambrian, South China

Longtancunella chengjiangensis, one of the sparse lingulid brachiopods from the Early Cambrian Chengjiang Lagerstatten of southwestern China, is characterized by a sub-circular shell shape, stout pedicle, and notably by gregarious occurrences in the fossils. This brachiopod form was briefly reported in 1999, but its detailed description, however, remains to be done. The material in our collection is remarkably well preserved and allows accounts of the shell morphology and of valve interiors, including lophophores, mantle canals, and a digestive tract. When compared with the coeval lingulid brachiopod Xianshanella haikouensis Zhang & Han, 2004, L. chengjiangensis exhibits some distinct features, notably tenuous marginal setae and distinguishable mantle canals and a relative short pedicle tapering posteriorly.