A unified approach to one-dimensional elastic waves by the method of characteristics

Unified approach to one-dimensional elastic waves by method of characteristic

MCDIT 21 - A computer code for one-dimensional elastic wave problems

Computer program for one dimensional elastic wave problems connected with structural member

Geochemistry of reduced inorganic sulfur, reactive iron, and organic carbon in fluvial and marine surface sediment in the Laizhou Bay region, China

Understanding the geochemical cycling of sulfur in sediments is important because it can have implications for both modern environments (e.g., deterioration of water quality) and interpretation of the ancient past (e.g., sediment C/S ratios can be used as indicators of palaeodepositional environment). This study investigates the geochemical characteristics of sulfur, iron, and organic carbon in fluvial and coastal surface sediments of the Laizhou Bay region, China. A total of 63 sediment samples were taken across the whole Laizhou Bay marine region and the 14 major tidal rivers draining into it. Acid volatile sulfur, chromium (II)-reducible sulfur and elemental sulfur, total organic carbon, and total nitrogen were present in higher concentrations in the fluvial sediment than in the marine sediment of Laizhou Bay. The composition of reduced inorganic sulfur in surface sediments was dominated by acid volatile sulfur and chromium (II)-reducible sulfur. In fluvial sediments, sulfate reduction and formation of reduced inorganic sulfur were controlled by TOC and reactive iron synchronously. High C/S ratios in the marine sediments indicate that the diagenetic processes in Laizhou Bay have been affected by rapid deposition of sediment from the Yellow River in recent decades

An assessment of transient hydraulics phenomena and its characterization

A systematic search of the open literature was performed with the purpose of identifying the causes, effects, and characterization (modelling and solution techniques) of transient hydraulics phenomena. The governing partial differential equations are presented which were found to be used most often in the literature. Detail survey sheets are shown which contain the type of hydraulics problem, the cause, the modelling, the solution technique utilized, and experimental verification used for each paper. References and source documents are listed and a discussion of the purpose and accomplishments of the study is presented

Wave propagation in stepped and joined shells Annual report, 1 Sep. 1968 - 1 Sep. 1969

Shell impact response and wave propagation in cylindrical and conical shells by experimental and analytical method

Sustainability Disclosure in the Leather Industry: A Content Analysis of Selected Sustainability Reports

Content: In today’s business environment, organisations are increasingly reporting their sustainability credentials through different channels. However, in a traditional industry with a complex supply chain as leather, many companies do not publicly disclose details of their sustainability activities, while a considerable number of companies report on the environmental sustainability aspect alone. Hence, this study identifies good practices of sustainability reporting, discussing the sustainability information extracted from the reports of a selected number of companies in the leather industry. A thematic content analysis was used to extract sustainability information from either the website, annual report, sustainability report or corporate social responsibility report of six leather companies. A review of existing literature assisted in categorising different practices under the three sustainability dimensions while a highlight of patterns among practices followed. The results show that the companies are observing a good practice of either dedicating a section of their website to revealing their sustainability activities or utilising their sustainability reports. Additionally, these companies follow a good practice of reporting their activities based on the economic, social and environmental sustainability dimensions, rather than focusing on just one of the aspects. Amongst the six companies, energy efficiency and reduction in greenhouse gases emission were the most occurring environmental sustainability practices. On the other hand, health and safety occurred as the dominant social sustainability practice of the leather industry, while economic sustainability practices have not been well defined, providing an opportunity for future research. Conclusively, the study provides a useful resource for managers and companies in the leather industry to learn from brands that have been embarking on sustainability efforts and assist them in getting a grasp of the concept, in readiness for strategy formulation, implementation and reporting. This study provides knowledge of the sustainability criteria to be met by small, medium sized and large leather supply chain actors on their sustainability journey. Take-Away: 1. The companies are observing a good practice of either dedicating a section of their website to revealing their sustainability activities or utilising their sustainability reports. 2. The companies also follow a good practice of reporting their activities based on the economic, social and environmental sustainability dimensions, rather than focusing on just one of the aspects. 3. Energy efficiency and reduction in greenhouse gases emission were the most popular environmental sustainability practices, health and safety was the dominant social sustainability practice while economic sustainability practices have not been well defined

Alteration of macroinvertebrate community in tropical aquatic systems in relation to sediment redox potential and overlaying water quality

Limnological studies in two tropical Indian aquatic habitats showed that macroinvertebrate communities have greater diversity than other biotic communities present there. Sediment redox potential is found to be an important factor for alteration of macroinvertebrate communities in aquatic bodies. Anthropogenic activities have influenced the changing of sediment redox potential values of the studied sites and there by affected the macroinvertebrate communities

Mechanism of Vanadium Leaching during Surface Weathering of Basic Oxygen Furnace Steel Slag Blocks: A Microfocus X-ray Absorption Spectroscopy and Electron Microscopy Study

© 2017 American Chemical Society. Basic oxygen furnace (BOF) steelmaking slag is enriched in potentially toxic V which may become mobilized in high pH leachate during weathering. BOF slag was weathered under aerated and air-excluded conditions for 6 months prior to SEM/EDS and μXANES analysis to determine V host phases and speciation in both primary and secondary phases. Leached blocks show development of an altered region in which free lime and dicalcium silicate phases were absent and Ca-Si-H was precipitated (CaCO 3 was also present under aerated conditions). μXANES analyses show that V was released to solution as V(V) during dicalcium silicate dissolution and some V was incorporated into neo-formed Ca-Si-H. Higher V concentrations were observed in leachate under aerated conditions than in the air-excluded leaching experiment. Aqueous V concentrations were controlled by Ca 3 (VO 4 ) 2 solubility, which demonstrate an inverse relationship between Ca and V concentrations. Under air-excluded conditions Ca concentrations were controlled by dicalcium silicate dissolution and Ca-Si-H precipitation, leading to relatively high Ca and correspondingly low V concentrations. Formation of CaCO 3 under aerated conditions provided a sink for aqueous Ca, allowing higher V concentrations limited by kinetic dissolution rates of dicalcium silicate. Thus, V release may be slowed by the precipitation of secondary phases in the altered region, improving the prospects for slag reuse

Single introductions of soil biota and plants generate long-term legacies in soil and plant community assembly

Recent demonstrations of the role of plant-soil biota interactions have challenged the conventional view that vegetation changes are mainly driven by changing abiotic conditions. However, while this concept has been validated under natural conditions, our understanding of the long-term consequences of plant- soil interactions for above-belowground community assembly is restricted to mathematical and conceptual model projections. Here, we demonstrate experimentally that one-time additions of soil biota and plant seeds alter soil-borne nematode and plant community composition in semi-natural grassland for 20 years. Over time, aboveground and belowground community composition became increasingly correlated, suggesting an increasing connectedness of soil biota and plants. We conclude that the initial composition of not only plant communities, but also soil communities has a long-lasting impact on the trajectory of community assembly

Analysis of Axially Symmetric Motions of Fig. 2 Longitudinal stress resultant Nx at times T = 0.5, T = 0.75, and 1 Cylindrical Shells by the Method of Characteristics

(10) The variables along the impulsive leading wave are now determined and the remainder solution domain is integrated by the characteristics finite-difference technique. An Initial Boundary-Value Problem An initial boundary-value problem is considered whore the developed scheme is demonstrated. The problem consists of a two-layered cylindrical membrane shell subjected to an impulsive axisymmetric load applied at one end of the finite shell, where N Xa is the peak magnitude taken to be unity and ^ is a damping factor taken to be 10 5 1/sec for this example. The dimensionless length of the first layer is taken to be 0.5 and the second layer is 0.125 long. Material properties are as follows: pi = p % = 2.4 X 10-* lb-sec 2 /in. 4 , G hl = 2.45 X 10 6 ips, vi = Vs, Vi = 7o, Ei = 12.8 X 10 6 psi, Ei = 3.5 X 10 6 psi, and R = 24.5 in. Time integration increment is taken to be AT = 0.01. Conclusions and Results The study presented a method for the solution of impulsive stress wave-propagation problems in layered shells. A twolayered shell impacted by a longitudinal axisymmetric load was solved in detail. By examining the results