Mathematical Modeling of Particle Stratification in Jigs

Recognizing mathematical modeling as a powerful tool for systematic process analysis and control, this paper attempts to critically'review the theories and mathem-atical models which have been advanced to explain and simulate the behaviour ofjigg ing process. The existing literature on mathematical modeling and quantitative analysis of jigging has been divided into six subheads : (i) classical theory, (ii) potential theory, (iii) dispersion models, (iv) energy dissipation theory, (v) stochastic analysis and (vi) empirical models. A new modeling approach based on Newtonian mechanics is used to describe the stratification behavior of particles in jig. In this approach,the motion of solid material is treated using the discrete element method (DEM) while the corre-sponding motion of the liquid is determined by marker and cell (MAC) technique. For illustration purpose, a jig bed consisting of 100 particles of two different densities is simulated. Preliminary results show that the model predicts the stratification of particles reasonably well

Application of Molecular Pathology Techniques to Understand Mechanisms of Disease in Smallmouth Bass

In the Chesapeake Bay drainage, smallmouth bass Micropterus dolomieu are used as an indicator species of estrogenic contaminant exposure and have been implicated in fish kills and disease since 2005. In the Potomac River drainage, adult smallmouth bass have experienced mortality and disease and males have a high prevalence of intersex (testicular oocytes). Conversely, in the Susquehanna River drainage mortalities and disease of young-of-the-year smallmouth bass (YOY SMB) have occurred and resulted in a population shift to older and larger fish. The exact cause of these events remains unknown; however, factors such as poor water quality, contaminants, pathogens and parasites, increased temperatures, and nutrification have been assessed. In order to address this issue, the USGS Fish Health Branch, Leetown Science Center, and West Virginia Cooperative Fish and Wildlife Research Unit have ongoing assessment and monitoring projects throughout the Chesapeake Bay watershed. The use of routine histopathology has provided guidance for further research with molecular endpoints that may help explain the mechanisms involved in disease in smallmouth bass. The purpose of this dissertation research was to: 1.) Identify the prevalence of coinfections and risk factors of disease in YOY SMB; 2.) Use in situ hybridization to identify coinfections of bacteria with the myxozoan parasite Myxobolus inornatus in YOY smallmouth bass; 3.) Model liver helminths and coinfections of YOY SMB with land use at two spatial scales; 4.) Develop laser capture microdissection methods for nucleic acid extractions which could be used with smallmouth bass tissues; and 5.) Utilize Next-Generation Sequencing to develop a partial testes transcriptome to identify molecular markers that may help explain intersex development in male smallmouth bass

Simulation of industrial gravity separation processes using a general purpose simulator

Gravity separation processes have been used in the mineral industry to separate particles under the action of hydr-odynamic and gravitational forces. Although these equip-ments are extensively used for tonnage processing in coal industry, their use has been now extended to waste trea-tment such as separation of valuable metallic matter from slag. However, these processes never run at their best due to lack of understanding of the process and the under-lying principles of separation. For efficient operation it is desirable that trial runs and pilot tests are conducted but these are often time consuming and expensive. Against this background, this paper attempts to show the capabi-lities of numerical simulation to gain a better under-standing of the process with a view to improve its performance.Data from different coal washeries are colle-cted to simulate the behaviour of the plants. Results of simulation utilizing jigging for coal washing is found to be in good agreement with the plant data. The same coal is also treated in other gravity separation processes in order to decide upon a particular washing circuit

Reactions of Pyruvonitrile with Nb(V) & Ta(V) Alkoxides

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Are you getting sick? Predicting influenza-like symptoms using human mobility behaviors

Understanding and modeling the mobility of individuals is of paramount importance for public health. In particular, mobility characterization is key to predict the spatial and temporal diffusion of human-transmitted infections. However, the mobility behavior of a person can also reveal relevant information about her/his health conditions. In this paper, we study the impact of people mobility behaviors for predicting the future presence of flu-like and cold symptoms (i.e. fever, sore throat, cough, shortness of breath, headache, muscle pain, malaise, and cold). To this end, we use the mobility traces from mobile phones and the daily self-reported flu-like and cold symptoms of 29 individuals from February 20, 2013 to March 21, 2013. First of all, we demonstrate that daily symptoms of an individual can be predicted by using his/her mobility trace characteristics (e.g. total displacement, radius of gyration, number of unique visited places, etc.). Then, we present and validate models that are able to successfully predict the future presence of symptoms by analyzing the mobility patterns of our individuals. The proposed methodology could have a societal impact opening the way to customized mobile phone applications, which may detect and suggest to the user specific actions in order to prevent disease spreading and minimize the risk of contagion

A tool for the rapid seismic assessment of historic masonry structures based on limit analysis optimisation and rocking dynamics

This paper presents a user-friendly, CAD-interfaced methodology for the rapid seismic assessment of historic masonry structures. The proposed multi-level procedure consists of a two-step analysis that combines upper bound limit analysis with non-linear dynamic (rocking) analysis to solve for seismic collapse in a computationally-efficient manner. In the first step, the failure mechanisms are defined by means of parameterization of the failure surfaces. Hence, the upper bound limit theorem of the limit analysis, coupled with a heuristic solver, is subsequently adopted to search for the load multiplier’s minimum value and the macro-block geometry. In the second step, the kinematic constants defining the rocking equation of motion are automatically computed for the refined macro-block model, which can be solved for representative time-histories. The proposed methodology has been entirely integrated in the user-friendly visual programming environment offered by Rhinoceros3D + Grasshopper, allowing it to be used by students, researchers and practicing structural engineers. Unlike time-consuming advanced methods of analysis, the proposed method allows users to perform a seismic assessment of masonry buildings in a rapid and computationally-efficient manner. Such an approach is particularly useful for territorial scale vulnerability analysis (e.g., for risk assessment and mitigation historic city centres) or as post-seismic event response (when the safety and stability of a large number of buildings need to be assessed with limited resources). The capabilities of the tool are demonstrated by comparing its predictions with those arising from the literature as well as from code-based assessment methods for three case studies.This work was partly funded by project STAND4HERITAGE that has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (Grant agreement No. 833123), as an Advanced Grant

Dynamic simulation of one-sided rocking masonry façades using an energy-consistent viscous damping model

Unreinforced masonry façades are specifically vulnerable to seismic actions. Their weak connectivity with adjacent structural members results in their detachment during an earthquake, thus, forming local collapse mechanisms which exhibit one-sided rocking motion. Such mechanisms can accommodate considerable displacements before collapsing/overturning. Hence, their dynamic stability is of great interest. The dynamic response of such collapse mechanisms has been investigated using the classical rocking theory. This is a reliable and fast model that efficiently simulates the dynamic response and energy losses of rocking structures, yet limited to simple structural configurations. As the problem’s complexity increases (e.g. degrees of freedom, boundary conditions, and/or material nonlinearities) numerical modelling of such structures has been recently gaining momentum. However, despite the great advances of such numerical modelling techniques, simulation of energy losses still remains challenging. The present work proposes a novel numerical block-based model that efficiently simulates energy losses during one-sided rocking motion. Specifically, an equivalent viscous damping model is adopted and calibrated in a phenomenological fashion after the classical rocking theory. Importantly, the unilateral dashpot formulation of the proposed viscous damping model allows for an accurate replication of the impulsive nature of impacts. Ready-to-use predictive equations are presented, which are also validated against experimental results from literature

Bio-dissolution of metals from activated nodules of Indian Ocean

The biodissolution of valuable metals from ferro-manganese nodules of Indian Ocean in presence of Aspergillus niger is a slow process. In order to improve the kinetics of bioleaching, the sea nodules were activated in high energy attrition mill thereby changing the granulometry and surface charge characteristics of the particles. The zeta potential, particle size distribution and surface area of the activated material were recorded and bioleaching was carried out by A.niger in the pH range 4.0-5.5. The mechano-chemical activation of the mixed particles (≤ 75 µm) of nodules in 10 min reduced almost 86 % material to ≤ 10 µm size with a change in zeta potential from -18 to -34 mV. Bioleaching of metals from the activated nodules was compared with that of the dissolution pattern of metals in presence of A.niger without any pretreatment as well as those under the chemical leaching conditions. The results showed the bio-recovery of more than 95% copper, nickel and cobalt each in 15 days time when the nodules activated for 10 min was leached at 5 % (w/v) pulp density, 4.5 pH and 35 ºC temperature. Bio-leaching of these metals was observed to be similar from the nodules activated for 30 min. The non-activated nodules showed ≥ 89% metal recovery in 25 days under the above conditions. The mechano-chemical activation of sea nodules has thus been found to improve the kinetics of the process and has also resulted in to the availability of wider pH in the range of 4-5 for the processing