During spawning events, horseshoe crab eggs are released from the female＇s oviducts, and fertilized by one or more males. Eggs are shaped by the female into discrete clutches deposited in nests at depths of 10-20 cm ...During spawning events, horseshoe crab eggs are released from the female＇s oviducts, and fertilized by one or more males. Eggs are shaped by the female into discrete clutches deposited in nests at depths of 10-20 cm on intertidal estuarine beaches. Distinguishing between fxesh eggs and the early developmental stages is obfuscated by the large amount of dense, opaque yolk. The first unambiguous confirmation of development is the formation of the rudimentary prosomatie appendages at the ＂limb bud＂ stage. Several days thereafter, the outer chorion is shed and the developing embryo expands and undergoes a series of molts within the clear inner egg membrane. The trilobite （first iustar） stage thus attained may remain within the beach sedi- ments for several more weeks, until hatching is facilitated by environmental factors such as hydration, agitation, and osmotic shock that accompany the infiltration of seawater into the nests. Trilobites exhibit endogenous eirgatidal swimming rhythms that are entrained by mechanical agitation, suggesting that peaks in larval swimming are timed to coincide with periods of high water and the inundation of the nests. Larval swimming is limited and does not appear to result in long-distance dispersal. The limited dispersal of the larvae has important implications for the population dynamics of relatively isolated populations. The rate of larval development is highly plastic and is influenced by temperature, salinity, dissolved oxygen, and the presence of pollutants. The broad environmental tolerances of horseshoe crab embryos and larvae are important in understanding their current geographic distribution and their evolutionary persistence展开更多
In order to reduce product development cycle time, aerospace companies tend to develop various correlations integrating geometric and performance parameters. This paper covers the development of a parameterization mod...In order to reduce product development cycle time, aerospace companies tend to develop various correlations integrating geometric and performance parameters. This paper covers the development of a parameterization modeling, to be used in the preliminary design phase, for the turbine cover plate of an aero-engine. The parameterization modeling of the turbine cover plate is achieved by using commercial CAD （computer aided design） software processing in batch mode. Two main approaches are presented the outer face and the skeleton models. These models can then be integrated into an iterative process for designing optimal shapes. Both models are capable of reproducing existing cover plate with reasonable accuracy in relatively shorter time periods. However, the skeleton approach provides probably the best results in terms of flexibility and accuracy, but increases programming complexity and requires greater run times.展开更多
Because of permanent matter and energy accumulation in the sea marginal biotopes, communities of organisms adapted to these specific conditions are developed. Terms contour biotopes and contourobiont＇s communities we...Because of permanent matter and energy accumulation in the sea marginal biotopes, communities of organisms adapted to these specific conditions are developed. Terms contour biotopes and contourobiont＇s communities were proposed. These habitats are populated by a great variety of organisms with numerical superiority of early stages of development of hydrobionts. Therefore, contour biotopes are responsible for the reproduction of many species of plants and animals, including commercialiy ~rnportant species of invertebrate and fish. But as a result of natural physical and chemical processes, the same habitats accumulate many substances that are harmful to living organisms, especially for early ontogenetic stages. So here formed main hotspots, critical ecological zones in seas and oceans, which need to be monitored in the first place. Understanding of the key role of contour biotopes and communities in marine ecological processes development is an ecological imperative. Making of ecological diagnoses, prediction of possible departures from the ecological norm and prevention of serious negative events in the marine environment needs special consideration of contour biotopes and their inhabitants, which are underestimated in traditional marine biological and ecological investigations.展开更多
基金supported by a series of awards from New Jersey Sea Grantsupport from the U.S. Army Corps of Engineers, Philadelphia Districtsupported by National Park Service Grants Nos.CA518099049 and PS 180060016
文摘During spawning events, horseshoe crab eggs are released from the female＇s oviducts, and fertilized by one or more males. Eggs are shaped by the female into discrete clutches deposited in nests at depths of 10-20 cm on intertidal estuarine beaches. Distinguishing between fxesh eggs and the early developmental stages is obfuscated by the large amount of dense, opaque yolk. The first unambiguous confirmation of development is the formation of the rudimentary prosomatie appendages at the ＂limb bud＂ stage. Several days thereafter, the outer chorion is shed and the developing embryo expands and undergoes a series of molts within the clear inner egg membrane. The trilobite （first iustar） stage thus attained may remain within the beach sedi- ments for several more weeks, until hatching is facilitated by environmental factors such as hydration, agitation, and osmotic shock that accompany the infiltration of seawater into the nests. Trilobites exhibit endogenous eirgatidal swimming rhythms that are entrained by mechanical agitation, suggesting that peaks in larval swimming are timed to coincide with periods of high water and the inundation of the nests. Larval swimming is limited and does not appear to result in long-distance dispersal. The limited dispersal of the larvae has important implications for the population dynamics of relatively isolated populations. The rate of larval development is highly plastic and is influenced by temperature, salinity, dissolved oxygen, and the presence of pollutants. The broad environmental tolerances of horseshoe crab embryos and larvae are important in understanding their current geographic distribution and their evolutionary persistence
文摘In order to reduce product development cycle time, aerospace companies tend to develop various correlations integrating geometric and performance parameters. This paper covers the development of a parameterization modeling, to be used in the preliminary design phase, for the turbine cover plate of an aero-engine. The parameterization modeling of the turbine cover plate is achieved by using commercial CAD （computer aided design） software processing in batch mode. Two main approaches are presented the outer face and the skeleton models. These models can then be integrated into an iterative process for designing optimal shapes. Both models are capable of reproducing existing cover plate with reasonable accuracy in relatively shorter time periods. However, the skeleton approach provides probably the best results in terms of flexibility and accuracy, but increases programming complexity and requires greater run times.
文摘Because of permanent matter and energy accumulation in the sea marginal biotopes, communities of organisms adapted to these specific conditions are developed. Terms contour biotopes and contourobiont＇s communities were proposed. These habitats are populated by a great variety of organisms with numerical superiority of early stages of development of hydrobionts. Therefore, contour biotopes are responsible for the reproduction of many species of plants and animals, including commercialiy ~rnportant species of invertebrate and fish. But as a result of natural physical and chemical processes, the same habitats accumulate many substances that are harmful to living organisms, especially for early ontogenetic stages. So here formed main hotspots, critical ecological zones in seas and oceans, which need to be monitored in the first place. Understanding of the key role of contour biotopes and communities in marine ecological processes development is an ecological imperative. Making of ecological diagnoses, prediction of possible departures from the ecological norm and prevention of serious negative events in the marine environment needs special consideration of contour biotopes and their inhabitants, which are underestimated in traditional marine biological and ecological investigations.
