An experimental facility for testing loaded structures in a high hydrostatic pressure environment and an application to axially loaded columns     

Richard P. Shaw  John Sezna 《Ocean Engineering》1971

An experimental facility is described for the testing of structures under a combined axial load and hydrostatic pressure load. This facility was used to determine the effects of hydrostatic pressure (up to 6000 psi) on the load-carrying capacity of slender metal columns. There appeared to be no significant effect in this case.  相似文献   

A sample changer for automated seawater nutrient analysis systems     

Richard D. Tomlinson  Louis I. Gordon 《Ocean Engineering》1973,2(4):179-182

An automatic sample changer based upon a commercially available 20-port rotary valve has been developed for use in automated seawater nutrient analyses. All parts exposed to seawater are of stainless steel, Teflon®, or Kel-F®. The sampler has proven to be rugged and efficient in both shore and shipboard laboratories.  相似文献   

Implementation of an expert system for the design of single-point, subsurface oceanographic moorings     

Santhosh Kumaran  Richard A. Skop 《Ocean Engineering》1990,17(4)

The design of single-point, subsurface moorings is carried out a present by a design engineer with the help of some computer programs. These computer programs are used for analyzing the mooring, but the setting-up of the initial mooring configuration and the subsequent modifications on the basis of the results of the analysis are carried out by the design engineer.An expert system for mooring design is developed to eliminate the human expert from the design process and thus to enable a novice to design a mooring by himself. Using the expert system, an optimum least-weight in air design can be developed in much less time than is usually required in conventional procedures. Perhaps the most significant advantage is that the system can serve as a vehicle for effective transfer of present day expertise for future applications.The system is developed and implemented on an IBM PC/AT. It has a user-friendly, interactive, menu-driven input procedure and a sophisticated output facility. The design process is totally automated and the requirement to consult a human expert is easily eliminated. The system has tremendous flexibility and a knowledge engineer can easily adapt it to the specific requirements of a particular user. The concept of machine learning is introduced by recording the failure data and using this information in the later decision-making processes. A CAD package, AUTOCAD, is used to generate the drawings and an interface is developed between the CAD package and the expert system so that the former is transparent to the user.  相似文献   

Source regions for recruitment of Calanus finmarchicus to Georges Bank: evidence from molecular population genetic analysis of mtDNA     

Ann Bucklin  Thomas D. Kocher 《Deep Sea Research Part II: Topical Studies in Oceanography》1996,43(7-8)

Molecular population genetic analysis has provided evidence that the copepod, Calanus finmarchicus, of the Labrador Current, Gulf of St Lawrence, Scotian Shelf, Gulf of Maine, and Georges Bank constitute a single, interbreeding population. The DNA sequence of a 350 base pair portion of the mitochondrial large subunit (16S) ribosomal RNA (rRNA) gene was determined for a total of 72 individuals collected in 1992, and 110 individuals collected in 1993 from these regions. There was significant heterogeneity in haplotype frequencies among the samples collected in 1992, but this heterogeneity did not resolve into regional patterns. The only regional differences seen were between pooled samples of the western N. Atlantic and those of the Norwegian Sea. There were no significant differences in haplotype frequencies among the samples collected in 1993, and fewer haplotypes were observed in these samples. Intraspecific molecular variation was typical of other marine species: there were 29 haplotypes among the 182 individuals sequenced. The frequency distribution of the haplotypes was highly skewed: 128 individuals shared one haplotype and 19 individuals were unique. There were 24 variable sites among the 350 bases sequenced; estimated nucleotide diversity was 0.0042. The genetic character of C. finmarchicus populations in the western N. Atlantic was stable over time in that three of the haplotypes (including the most abundant) occurred in both 1992 and 1993. However, haplotype frequencies differed significantly between the two years. The lack of regional structure in the 1992 samples and the genetic homogeneity of samples collected in 1993 across the domain from the Labrador Current to the Gulf of St Lawrence to Georges Bank and the Gulf of Maine indicated that there is significant gene flow across this region. The persistent genetic pattern suggests that the Gulf of St Lawrence may be an important source region for recruitment of C. finmarchicus to Georges Bank. Determination of zooplankton dispersal patterns within high gene flow species will provide information that may not be determined by conventional oceanographic analyses.  相似文献   

Circulation on the north central Chukchi Sea shelf   总被引：8，自引：0，他引：8  

Thomas Weingartner  Knut Aagaard  Rebecca Woodgate  Seth Danielson  Yasunori Sasaki  Donald Cavalieri 《Deep Sea Research Part II: Topical Studies in Oceanography》2005,52(24-26):3150

Mooring and shipboard data collected between 1992 and 1995 delineate the circulation over the north central Chukchi shelf. Previous studies indicated that Pacific waters crossed the Chukchi shelf through Herald Valley (in the west) and Barrow Canyon (in the east). We find a third branch (through the Central Channel) onto the outer shelf. The Central Channel transport varies seasonally in phase with Bering Strait transport, and is 0.2 Sv on average, although some of this might include water entrained from the outflow through Herald Valley. A portion of the Central Channel outflow moves eastward and converges with the Alaskan Coastal Current at the head of Barrow Canyon. The remainder appears to continue northeastward over the central outer shelf toward the shelfbreak, joined by outflow from Herald Valley. The mean flow opposes the prevailing winds and is primarily forced by the sea-level slope between the Pacific and Arctic oceans. Current variations are mainly wind forced, but baroclinic forcing, associated with upstream dense-water formation in coastal polynyas might occasionally be important.Winter water-mass modification depends crucially on the fall and winter winds, which control seasonal ice development. An extensive fall ice cover delays cooling, limits new ice formation, and results in little salinization. In such years, Bering shelf waters cross the Chukchi shelf with little modification. In contrast, extensive open water in fall leads to early and rapid cooling, and if accompanied by vigorous ice production within coastal polynyas, results in the production of high-salinity (>33) shelf waters. Such interannual variability likely affects slope processes and the transport of Pacific waters into the Arctic Ocean interior.  相似文献   

Morphology and tectonics of the Romanche Transform and its environs     

R. C. Searle  M. V. Thomas  E. J. W. Jones 《Marine Geophysical Researches》1994,16(6):427-453

  相似文献   

Patterns of heritability of decreased EROD activity and resistance to PCB 126-induced teratogenesis in laboratory-reared offspring of killifish (Fundulus heteroclitus) from a creosote-contaminated site in the Elizabeth River,VA, USA     

Meyer J  Di Giulio R 《Marine environmental research》2002,54(3-5):621-626

Killifish (Fundulus heteroclitus) from a highly contaminated site on the Elizabeth River are resistant to the acute toxicity and the cytochrome P4501A (CYP1A)-inducing activity of both the sediments from the site and chemically pure polycyclic aromatic hydrocarbons (PAHs). These effects are highly heritable for one generation, but heritable to a lesser degree by subsequent generations, in clean conditions in the laboratory. We show that offspring of this population of Elizabeth River killifish are also resistant to the teratogenicity and P4501A-inducing activity of PCB congener 126, a prototypical coplanar halogenated aromatic hydrocarbon (HAH). Furthermore, the pattern of greater resistance to acute toxicity and P4501A-inducing activity in the first generation and less in subsequent generations is also observed upon exposure to PCB-126.  相似文献   

The role of sex change, growth and mortality in Pandalus population dynamics and management     

Fu  Caihong; Quinn  Terrance J.  II; Shirley  Thomas C. 《ICES Journal of Marine Science》2001,58(3):607-621

  相似文献   

Fishing, selection, and phenotypic evolution   总被引：10，自引：9，他引：10  

Law  Richard 《ICES Journal of Marine Science》2000,57(3):659-668

  相似文献   

Circulation     

Thomas N. Lee  Leonard J. Pietrafesa 《Progress in Oceanography》1987,19(3-4)

Low-frequency current and temperature variability on the southeast US continental shelf during summer conditions of weak wind forcing and vertical stratification was found to be similar in many aspects to previous findings for winter, when stronger wind forcing and vertical homogeneity prevails. Subtidal variability in the outer shelf is dominated by the weekly occurrence of Gulf Stream frontal eddies and meanders. These baroclinic events strongly affect the balance of momentum in the outer shelf, but not at mid-shelf. A negative alongshore sea level slope of order −10⁻⁷ is required to balance mean along-shelf momentum at the shelf edge, similar to oceanic estimates, and can contribute to the observed northward mean flow over the shelf.Low-frequency flow at mid-shelf and coastal sea level fluctuations appear to occur as a forced wave response to local alongshore wind stress events that are coherent over the shelf domain. Momentum balances indicate a trapped wave response similar to the arrested topographic wave found in the mid-Atlantic Bight (CSANADY, 1978). Density driven currents from river discharge do not appear to be significant at mid-shelf. Cold, subsurface intrusions of deeper, nutrient rich Gulf Stream waters can occasionally penetrate to mid- and inner-shelf regions north of Cape Canaveral, causing strong phytoplankton and zooplankton responses. These events were observed following the simultaneous occurrence of upwellings from northward winds and Gulf Stream frontal eddies at the shelf break during periods when the Stream was in an onshore position. Subsurface Gulf Stream intrusions to mid-shelf occur only during the summer, when the shelf is vertically stratified and cross-shelf density gradients do not present a barrier as in winter.  相似文献