A bodner-partom visco-plastic dynamic sphere benchmark problem

Developing benchmark analytic solutions for problems in solid and fluid mechanics is very important for the purpose of testing and verifying computational physics codes. Our primary objective in this research is to obtain a benchmark analytic solution to the equation of motion in radially symmetric spherical coordinates. An analytic solution for the dynamic response of a sphere composed of an isotropic visco-plastic material and subjected to spherically symmetric boundary conditions is developed and implemented. The radial displacement u is computed by solving the equation of motion, a linear second-order hyperbolic PDE. The plastic strains εp and εp are computed by solving two non-linear first-order ODEs in time. We obtain a solution for u in terms of the plastic strain components and boundary conditions in the form of an infinite series. Computationally, at each time step, we set up an iteration scheme to solve the PDE-ODE system. The linear momentum equation is solved using the plastic strains from the previous iteration, then the plastic strain equations are solved numerically using the new displacement. We demonstrate the accuracy and convergence of our benchmark solution under spatial mesh, time step, and eigenmode refinement

EVALUATION OF PRODUCTION-WELL PERFORMANCE IN RESPONSE TO FORMATION CLOGGING AND REHABILITATION FOR THE KEWEENAW BAY TRIBAL FISH HATCHERY

Temporally, the KBIC (Keweenaw Bay Indian Community) Hatchery wells have manifested general trends of declining specific capacity and higher energy consumption due to mineral precipitation in and around the production wells. Monitoring data, laboratory water analyses, and downhole video logging have confirmed that naturally occurring minerals are precipitating and clogging the screens and, likely, the surrounding formations. The reduction in fluid pressures in and around the well-screens from active pumping wells is typical but, ultimately alters the geochemical and physical conditions such that dissolved minerals precipitate on and around the well-screens, therefore, effectively clogging the well. The clogging from mineral precipitation results in increased drawdown causing more pressure losses and clogging, and so on. Consequently, the pumps work harder and ultimately increase energy consumption and reduce production efficiencies. The Hatchery’s SCADA system now provides the ability to monitor flows and drawdowns, which reflect important information regarding well field performance. To be more economically strategic in managing the well field operations it is apparent that the performance data from the SCADA system must be utilized to conserve well-field-related costs. The analysis of the SCADA data clearly shows that the production well’s performance diminishes with use over time due to well-screen plugging because of mineral precipitation in and around the well-screen. The observed regained performance from well rehabilitation efforts (mechanical scrubbing and/ or acid treatment) demonstrates their effectiveness, and with the use of the spreadsheet tool (developed for the KBIC Hatchery production well field), the frequency of rehabilitation efforts can be assessed on a more financially sound basis by forecasting a relative breakeven cost-benefit analysis for a particular well and associated rehabilitation. The economic analysis of power consumption and treatment costs suggests that well-treatment costs can be recovered in approximately 6-9 years based on the treatment\u27s effectiveness in offsetting the performance declination due to mineral precipitation from pumping and relative drawdown. In other words, the magnitude of the regained well performance will be proportional to the rehabilitation method’s effectiveness in removing the mineral precipitation buildup and unclogging the well screen. The SCADA system is invaluable for monitoring, understanding, and managing the well field. The continued use of the SCADA system and implementation of the other recommendations in this report will be financially beneficial as more informed flow-management decisions can be made with confidence. Furthermore, to improve life on our planet through more sustainable approaches to groundwater management, the continued development of computational tools that utilize field monitoring data in making strategic decisions for well rehabilitation and minimizing drawdown will be essential for groundwater optimization and energy cost reduction now and in the future

Integrating Real Practical Experience in ICT Education

An important challenge for advancing the quality of education in Information and Communication Technology (ICT) is to integrate education and practical experience. It is sensible to start such active learning already in an early stage of the curriculum, in a valuable, real-life, and effective manner. It is desirable to reach that goal in such a durable way that we can easily account for the continuous changes and extensions in the underlying ICT itself. This paper presents our experiences in integrating ICT education and practice from an educational designer\u27s point of view. We will give several hints on how to design such an integrated curriculum module. We first explicate which educational design questions deserve attention in designing such a module. For each such design question we present the solution we chose, some specific examples, our experiences over the years (gradually improving the organization of such a module), and alternative solutions there might be. We also give some quantitative information

The Chinese Steel Industry: Global Challenges in an Economic Perspective

The Chinese steel industry is an issue that elicits many interesting economic questions. My research will analyze the relationship between the quantity of Chinese steel imports and domestic prices for equivalent steel products in an effort to both ascertain the relationship and to emphasize the importance and relevance of understanding the structure and operation of the Chinese steel industry

Study of an engine flow diverter system for a large scale ejector powered aircraft model

Requirements were established for a conceptual design study to analyze and design an engine flow diverter system and to include accommodations for an ejector system in an existing 3/4 scale fighter model equipped with YJ-79 engines. Model constraints were identified and cost-effective limited modification was proposed to accept the ejectors, ducting and flow diverter valves. Complete system performance was calculated and a versatile computer program capable of analyzing any ejector system was developed

More hedging instruments may destabilize markets

This paper formalizes the idea that more hedging instruments may destabilize markets when traders are heterogeneous and adapt their behavior according to experience based reinforcement learning. We investigate three different economic settings, a simple mean-variance asset pricing model, a general equilibrium two-period overlapping generations model with heterogeneous expectations and a noisy rational expectations asset pricing model with heterogeneous information signals. In each setting the introduction of additional Arrow securities can destabilize the market, causing a bifurcation of the steady state to multiple steady states, periodic orbits or even chaotic fluctuations

Isolation of anaerobic, extremely thermophilic, sulphur metabolising archaebacteria from New Zealand hot springs

Enrichments of New Zealand geo-thermal samples, initiated in anaerobic sulphur-containing media and incubated at temperatures above 85°C, yielded rod and coccal shaped organisms which possessed archaebacterial characteristics. Pure cultures were isolated and characterised. Five of the seven isolates, which were rod-shaped organisms and did not have an obligate requirement for sulphur respiration, were similar to Ther-moproteus sp. but had more neutral pH optima for growth. Three of these five Thermoproteus sp. were obligate heterotrophs, which has not previously been reported. The two coccal isolates had an obligate requirement for sulphur as an electron acceptor and were similar to Desulfurococcus sp. but again with more neutral pH optima for growth

Synthesis, Structure and Properties of Tetragonal Sr2M3As2O2 (M3 = Mn3, Mn2Cu and MnZn2) Compounds Containing Alternating CuO2-Type and FeAs-Type Layers

Polycrystalline samples of Sr2Mn2CuAs2O2, Sr2Mn3As2O2, and Sr2Zn2MnAs2O2 were synthesized. Their temperature- and applied magnetic field-dependent structural, transport, thermal, and magnetic properties were characterized by means of x-ray and neutron diffraction, electrical resistivity rho, heat capacity, magnetization and magnetic susceptibility measurements. These compounds have a body-centered-tetragonal crystal structure (space group I4/mmm) that consists of MO2 (M = Zn and/or Mn) oxide layers similar to the CuO2 layers in high superconducting transition temperature Tc cuprate superconductors, and intermetallic MAs (M = Cu and/or Mn) layers similar to the FeAs layers in high-Tc pnictides. These two types of layers alternate along the crystallographic c-axis and are separated by Sr atoms. The site occupancies of Mn, Cu and Zn were studied using Rietveld refinements of x-ray and neutron powder diffraction data. The temperature dependences of rho suggest metallic character for Sr2Mn2CuAs2O2 and semiconducting character for Sr2Mn3As2O2 and Sr2Zn2MnAs2O2. Sr2Mn2CuAs2O2 is inferred to be a ferrimagnet with a Curie temperature TC = 95(1) K. Remarkably, we find that the magnetic ground state structure changes from a G-type antiferromagnetic structure in Sr2Mn3As2O2 to an A-type ferrimagnetic structure in Sr2Mn2CuAs2O2 in which the Mn ions in each layer are ferromagnetically aligned, but are antiferromagnetically aligned between layers.Comment: 18 pages, 16 figures, 6 tables; submitted to Phys. Rev.