A general formulation of the theory of wire ropes

The author claims to have developed a simple and well-organized approach towards the formulation of wire strand and rope problems. He considers both the geometric nonlinear theory as well as the linearized theory, and while stating the ease in programming his theory, no numerical results are presented. The continued interest in wire strand and rope behavior exemplifies the importance of these elements. However, the author has missed a whole body of literature over the last ten years which has previously provided generalized theories for wire strands and ropes, and has done so in a much more usable form. In general, the theory of wire rope has been well developed by Costello and his associates, whose references are too numerous to mention, and they have examined a wide variety of problems from linear and nonlinear response of wire strands and ropes under static and dynamics loads to the response of viscoelastic ropes to the response of strands and ropes comprised of wires with various types of cross-sectional geometry. Typical of these works are the development of the basic theory and their use in the examination of specific wire rope problems. A few of the papers will be discussed to follow which have already accomplished fat" more than the paper under discussion. First, as noted above, Jiang (1995) presents both the geometrically nonlinear and linear theories. Costello and his associates use the wire rope axial and rotational strain to describe the deformation behavior of the total rope. Jiang in Eq. (18) of his paper also uses these parameters. One aspect should be noted, however, and that is that Jiang's rotational strain, qS, is not dimensionless. Jiang states as one of his primary contributions is his showing that the strand structure can be characterized by seven stiffness and deformation constants. This is not a new idea. Velinsky (1988) stated, "We note that the global behavior of a strand can be completely described by the following strand quantifies: the stiff-J Jiang, W., 1995, "A General Formulation of the Theory of Wire Ropes," ASME JOURNAL OF APPLIED MECHANICS, Vol. 62, pp, 747-755. z Professor, Department of Mechanical and Aeronautical Engineering, University of California-Davis, Davis, CA 95616. ness constants, $1, Sz,$3, and $4, the effective strand radius, R*, the strand effective Poisson's ratios, ue, and Ue~, and the strand bending stiffness, A*." Velinsky has eight constants, and the reason is that the strand size is necessary which Jiang has omitted. It should also be noted that Jiang uses a different notation which is much less intuitive, but represents essentially the same parameters. It should also be stressed that these strand describing coefficients are all constants only for the linear theory (e.g., the stiffness varies with load for the nonlinear theory). The Velinsky Velinsky (1989) later extended the generalized approach of his 1988 paper to examine complex wire rope design. The Velinsky 1989 paper develops the general analysis for wire strand core, independent wire rope core, and fiber core types of wire ropes. The total rope analysis requires only the eight parameters for each strand, and a similar set of three linear equations are necessary for the deformations of each strand lay. Furthermore, as in the earlier paper, the theory is exercised in examining the sensitivities of various total rope properties to numerous strand and rope design parameters. In addition to total rope properties, Velinskky also examines the sensitivities of rope design parameters on individual wire stresses. The Velinsky formulation is easily programmed in a general manner (and has been), and is easily exercised as exhibited by the large amount of results that have been presented

A review of nitrogen isotopic alteration in marine sediments

Key Points: Use of sedimentary nitrogen isotopes is examined; On average, sediment 15N/14N increases approx. 2 per mil during early burial; Isotopic alteration scales with water depth Abstract: Nitrogen isotopes are an important tool for evaluating past biogeochemical cycling from the paleoceanographic record. However, bulk sedimentary nitrogen isotope ratios, which can be determined routinely and at minimal cost, may be altered during burial and early sedimentary diagenesis, particularly outside of continental margin settings. The causes and detailed mechanisms of isotopic alteration are still under investigation. Case studies of the Mediterranean and South China Seas underscore the complexities of investigating isotopic alteration. In an effort to evaluate the evidence for alteration of the sedimentary N isotopic signal and try to quantify the net effect, we have compiled and compared data demonstrating alteration from the published literature. A >100 point comparison of sediment trap and surface sedimentary nitrogen isotope values demonstrates that, at sites located off of the continental margins, an increase in sediment 15N/14N occurs during early burial, likely at the seafloor. The extent of isotopic alteration appears to be a function of water depth. Depth-related differences in oxygen exposure time at the seafloor are likely the dominant control on the extent of N isotopic alteration. Moreover, the compiled data suggest that the degree of alteration is likely to be uniform through time at most sites so that bulk sedimentary isotope records likely provide a good means for evaluating relative changes in the global N cycle

Micro-spectroscopic investigation of selenium-bearing minerals from the Western US Phosphate Resource Area

Mining activities in the US Western Phosphate Resource Area (WPRA) have released Se into the environment. Selenium has several different oxidation states and species, each having varying degrees of solubility, reactivity, and bioavailability. In this study we are investigating the speciation of Se in mine-waste rocks. Selenium speciation was determined using bulk and micro-x-ray absorption spectroscopy (XAS), as well as micro-x-ray fluorescence mapping. Rocks used for bulk-XAS were ground into fine powders. Shale used for micro-XAS was broken along depositional planes to expose unweathered surfaces. The near edge region of the XAS spectra (XANES) for the bulk rock samples revealed multiple oxidation states, with peaks indicative of Se(-II), Se(IV), and Se(+VI) species. Micro-XANES analysis of the shale indicated that three unique Se-bearing species were present. Using the XANES data together with ab initio fitting of the extended x-ray absorption fine structure region of the micro-XAS data (micro-EXAFS) the three Se-bearing species were identified as dzharkenite, a di-selenide carbon compound, and Se-substituted pyrite. Results from this research will allow for a better understanding of the biogeochemical cycling of Se in the WPRA

Isotopic characterization of aerosol organic carbon components over the eastern United States

Author Posting. © American Geophysical Union, 2012. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 117 (2012): D13303, doi:10.1029/2011JD017153.Carbon isotopic signatures (δ13C, Δ14C) of aerosol particulate matter total organic carbon (TOC) and operationally defined organic carbon (OC) components were measured in samples from two background sites in the eastern U.S. TOC and water-soluble OC (WSOC) δ13C values (−27 to −24‰) indicated predominantly terrestrial C3 plant and fossil derived sources. Total solvent extracts (TSE) and their aliphatic, aromatic, and polar OC components were depleted in δ13C (−30 to −26‰) relative to TOC and WSOC. Δ14C signatures of aerosol TOC and TSE (−476 to +25‰) suggest variable fossil contributions (~5–50%) to these components. Aliphatic OC while comprising a small portion of the TOC (<1%), was dominated by fossil-derived carbon (86 ± 3%), indicating its potential utility as a tracer for fossil aerosol OC inputs. In contrast, aromatic OC contributions (<1.5%) contained approximately equal portions contemporary (52 ± 8%) and fossil (48 ± 8%) OC. The quantitatively significant polar OC fraction (6–25% of TOC) had fossil contributions (30 ± 12%) similar to TOC (26 ± 7%) and TSE (28 ± 9%). Thus, much of both of the fossil and contemporary OC is deduced to be oxidized, polar material. Aerosol WSOC consistently showed low fossil content (<8%) relative to the TOC (5–50%) indicating that the majority of fossil OC in aerosol particulates is insoluble. Therefore, on the basis of solubility and polarity, aerosols are predicted to partition differently once deposited to watersheds, and these chemically distinct components are predicted to contribute in quantitatively and qualitatively different ways to watershed carbon biogeochemistry and cycling.ASW was partially supported by a Graduate Fellowship from the Hudson River Foundation during the course of this study. Additional funding for this work came from a NOSAMS student internship award, a fellowship award from Sun Trust Bank administered through the VIMS Foundation, a student research grant from VIMS, and the following NSF awards: DEB Ecosystems grant DEB-0234533, Chemical Oceanography grant OCE-0327423, and Integrated Carbon Cycle Research Program grant EAR-0403949 to JEB; and Chemical Oceanography grant OCE-0727575 to RMD and JEB.2013-01-0