Comments on “Towed cable behaviour during ship turning manoeuvres” by D.A. Chapman,Ocean Engng 11 (4), 327–361 (1984).     

P.A.A. Laura 《Ocean Engineering》1985,12(5):471

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Forced vibrations of rectangular plates subjected to harmonic loading distributed over a rectangular subdomain     

R. E. Rossi  R. H. Gutirrez  P. A. A. Laura 《Ocean Engineering》2001,28(12)

Quite frequently naval and ocean structural designers confront the problem of a plate or slab which supports a motor or engine which excites, dynamically, the structural element. Very often the excitation is treated as a concentrated force but, obviously, it acts over a finite area. The present study deals with the title problem for several combinations of boundary conditions by means of a variational approach and also using the finite element method. Dynamic displacement and bending moment amplitudes are determined.  相似文献   

August J. Durelli: 1910–2000     

Patricio A. A. Laura 《Ocean Engineering》2002,29(6):591

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Comments on ‘dynamic analysis of a vertical plate exposed to breaking wave impact’     

P.A.A. Laura  C.A. Rossit  D.V. Bambill 《Ocean Engineering》2005,32(10):1278-1279

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Deep-Tow magnetics near 20°S on the East Pacific Rise: A study of short wavelength anomalies at a very fast spreading center     

Laura Jean Perram  Ken C. Macdonald  Stephen P. Miller 《Marine Geophysical Researches》1990,12(3):235-245

Six Deep-Tow magnetic profiles across the axis of the East Pacific Rise [EPR] in two small areas between 19°25 and 20°10S were collected during the 1983 Protea 1 cruise of the R/V Melville. These near-bottom profiles are of extremely high resolution allowing the interpretation of very short wavelength features. We have inverted the magnetic field data to determine the rock magnetization distribution near the axis of this ultrafast speading center (162 mm yr^-1). The solutions reveal large amplitude (up to 35 A m^-1) short wavelength (1–3 km) variations in magnetization. Specifically all crossings show a narrow (0.5 to 1.5 km) low in magnetization superimposed on a broader (2.5 to 4 km) high directly over the ridge axis. Four profiles in the northern area (19°25 to 19°33S) also show symmetrical near-axis (within 4 km) lows which are remarkably continuous along strike. Explanations for the short-wavelength variations are discussed which fall into the following categories: (1) variations in the thickness of the magnetized layer, (2) variations in rock chemistry (e.g. alteration due to hydrothermal activity), and (3) paleofield intensity variations. None of the mechanisms discussed alone adequately explain the observed phenomena in the study area or on a world-wide scale. Further sampling and high resolution surveying will be required in order to accurately determine the relative importance of the mechanisms discussed.  相似文献   

Free vibrations of rectangular plates elastically restrained against rotation with circular or square free openings     

P.A.A. Laura  R.H. Gutierrez  L. Ercoli  J.C. Utjest  R. Carnicer 《Ocean Engineering》1987,14(4)

The fundamental frequency of vibration of plates elastically restrained against rotation along the edges and with centrally located circular or square holes is determined by means of the optimized Rayleigh's method. Independent solutions are also obtained using the finite element method.A comparison with experimental values is also presented in the case where the plate is rigidly clamped along the four edges.  相似文献   

Evaluating the structural condition of synthetic and metallic cables     

P. A. A. Laura   《Ocean Engineering》1995,22(6)

In view of the fact that mechanical cables are very popular and powerful structural members, methods that provide information concerning their “health” are anxiously needed. In general, and because of their extended length (a rope used in a gold mine in South Africa is 9.3 miles long), methods which inspect the cable as a continuous function of the length variable are very expensive and time-consuming. The present paper surveys the state-of-the-art and discusses limitations and advantages of the techniques available today, the most recent one being the “induced, transverse wave propagation method”.  相似文献   

Increased toxicity of benzo(a)pyrene-7,8-dihydrodiol in the presence of polychlorobiphenylols     

Margaret O. James  Kevin M. Kleinow  Youbo Zhang  Ran Zheng  Liquan Wang  Laura R. Faux 《Marine environmental research》2004,58(2-5):343

Benzo(a)pyrene (BaP) and polychlorinated biphenyls (PCBs) often co-exist in contaminated environments. Polychlorobiphenylols (OH-PCBs), formed by CYP-dependent monooxygenation of PCBs, are potent inhibitors of the glucuronidation of hydroxylated BaP metabolites. We hypothesized that OH-PCBs could drive the biotransformation of (−)BaP-7,8-dihydrodiol (BaP-7, 8-D) away from detoxication and towards formation of the reactive metabolite. A mixture of five OH-PCBs with 4–6 Cl atoms was infused into isolated, perfused, biliary intact livers (n=3 fish) removed from 3-methylcholanthrene-induced channel catfish. Controls (n=3) were infused with vehicle. Subsequently, [³H]-BaP-7, 8-D was infused into each liver and bile was collected for 1 h. The livers were taken for analysis of metabolites and DNA adducts. Induction status was confirmed by EROD assay. Bile was analyzed for metabolites. It was found that preinfusion of the mixture of OH-PCBs reduced the extent of glucuronidation of BaP-7, 8-D and increased the formation of DNA adducts 5-fold over controls. GSH conjugates, tetrols and triols were increased in the OH-PCB-infused fish, providing further support for our hypothesis that if the glucuronidation were inhibited, CYP-dependent activation would increase. These studies suggest a mechanism for synergy of toxicity of PAH and PCBs.  相似文献   

Analysis of vibrating orthotropic rectangular plates by a modified Rayleigh-Ritz method     

P. A. A. Laura  J. P. Viazzi 《Ocean Engineering》1985,12(1):17-24

The title problem is solved in the case where the plate is clamped along two adjacent edges while the remaining are free. A mass is rigidly attached to the plate. The value of the fundamental frequency coefficient is conveniently minimized by means of Schmidt's approach. The methodology presented herewith can be extended without formal difficulties to other vibrating systems, e.g. the case of motors and engines elastically mounted on structural elements.  相似文献   

Reply to comments by M. Gürgöze     

C.A. RossitP.A.A. Laura 《Ocean Engineering》2002,29(13):1731

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