Robust backstepping controllers for linear motor drives

This work presents robust backstepping controllers to achieve position tracking control of a linear motor drive system with parameter uncertainties, discontinuous frictional force, and unknown external disturbance. First, a robust control scheme is developed to provide asymptotic stability under tracking control of the linear drive system. The assumption of a constant upper bound on the disturbance during the control design can lead to an overly conservative controller. To avoid this, an adaptation mechanism has been proposed to adapt the upper bound based on the current state measurement and the delayed state and input variables. The developed control scheme was shown to provide a global asymptotic stability of the closed-loop linear motor drive system. The control strategies are evaluated by numerical simulation of the linear motor drive. The simulation results show that the use of the adaptive disturbance upper bound adjustment technique results in significant performance improvement

Ariel - Volume 2 Number 2

Editors Delvyn C. Case, Jr. Paul M. Fernhoff News Editors Richard Bonanno Daniel B. Gould Ronald A. Hoffman Lay-Out Editor Carol Dolinskas Sports Editor James J. Nocon Contributing Editors MichaeI J. Blecker Lin Sey Edwards Jack Guralnik W. Cherry Light Features Editor Donald A. Bergman Stephen P. Flynn Business Manager Nick Grego Public Relations Robin A. Edward

Cytokine regulation of lung Th17 response to airway immunization using LPS adjuvant

Infections caused by bacteria in the airway preferentially induce a Th17 response. However, the mechanisms involved in the regulation of CD4 T-cell responses in the lungs are incompletely understood. Here, we have investigated the mechanisms involved in the regulation of Th17 differentiation in the lungs in response to immunization with lipopolysaccharide (LPS) as an adjuvant. Our data show that both Myd88 and TRIF are necessary for Th17 induction. This distinctive fate determination can be accounted for by the pattern of inflammatory cytokines induced by airway administration of LPS. We identified the production of interleukin (IL)-1β and IL-6 by small macrophages and IL-23 by alveolar dendritic cells (DCs), favoring Th17 responses, and IL-10 repressing interferon (IFN)-γ production. Furthermore, we show that exogenous IL-1β can drastically alter Th1 responses driven by influenza and lymphocytic choriomeningitis virus infection models and induce IL-17 production. Thus, the precision of the lung immune responses to potential threats is orchestrated by the cytokine microenvironment, can be repolarized and targeted therapeutically by altering the cytokine milieu. These results indicate that how the development of Th17 responses in the lung is regulated by the cytokines produced by lung DCs and macrophages in response to intranasal immunization with LPS adjuvant

Assessing heavy metal contamination using biosensors and a multi-branch integrated catchment model in the Awash River Basin, Ethiopia

Metal pollution in rivers from untreated industrial and domestic wastewater is a major issue in economically developing countries worldwide. The Awash River Basin in Ethiopia is one of those rivers that faces rising heavy metal concentrations due to poor wastewater management and loose law enforcement controlling effluent discharge into rivers. In this study, surface water and wastewater samples were collected within the Awash River Basin, with metals analysis using ICP-MS techniques. Acute toxicity of water was determined using new molecular biosensor technology based on engineered luminescent bacteria. A multi-branch Integrated Catchment Model (INCA) for metals, including Arsenic, Cadmium, Chromium, Copper, Lead, Manganese, and Zinc was applied to the Awash River Basin to simulate the impact of tannery discharge on the river water pollution levels and to evaluate a set of treatment scenarios for pollution control. Results show that all samples from tannery wastewater have high levels of metals, such as Chromium and Manganese with high levels of toxicities. River water samples from upper Awash near Addis Ababa showed elevated concentrations of heavy metals due to the untreated wastewater from the dense population and a large number of industries in that area. The modeling scenarios indicate that improved wastewater management will reduce the metal concentration significantly. With a 50% reduction in effluent concentrations, the mean concentrations of heavy metals (such as Chromium) over two years would be able to reach 20 to 50% reduction in river water samples

Ariel - Volume 2 Number 6

Editors Richard J. Bonanno Robin A. Edwards Associate Editors Steven Ager Stephen Flynn Shep Dickman Tom Williams Lay-out Editor Eugenia Miller Contributing Editors Michael J. Blecker W. Cherry Light James J. Nocon Lynne Porter Editors Emeritus Delvyn C. Case, Jr. Paul M. Fernhof

A new multibranch model for metals in river systems: Impacts and control of tannery wastes in Bangladesh

A new multibranch Integrated Catchment (INCA) model INCA-Metals has been developed to simulate the impact of tannery discharges on river systems. The model accounts for the key chemical reaction kinetic processes operating as well as sedimentation, resuspension, dilution, mixing and redistribution of pollutants in rivers downstream of tannery discharge points and for mine discharges or acid rock drainage sites. The model is dynamic and simulates the daily behaviour of hydrology and eight metals, including cadmium, mercury, copper, zinc, lead, arsenic, manganese and chromium, as well as cyanide and ammonia. The model is semi-distributed and can simulate catchments, tributaries and instream river behaviour. The model can also account for diffuse pollution from rural runoff as well as point sources from effluent and trade discharges. The model has been applied to the new Savar tannery complex on the Dhaleshwari River system in Bangladesh to assess the impacts on pollution levels in the river system and to evaluate a set of treatment scenarios for pollution control, particularly in the dry season. It is shown that the new effluent treatment plant at Savar needs to significantly improve its operation and treatment capability in order to alleviate metal pollution in the downstream Dhaleshwari River System and also protect the Meghna River System that falls in the Bay of Bengal

Developing new functional TCs

Transparent Conductors (TCs) are increasingly critical to the performance and reliability of a number of technologies. Traditionally based primarily on oxides of Ga, In, Zn and Sn the class is rapidly expanding into new materials including both other oxides and more recently composites of metallic or carbon nanowires. Many of these materials offer unique functionality as well as processing and reliability advantages over some of the historic materials. These compounds are all classically non-stoiciometric and often metastable consisting of oxide, non-oxide and composite materials which are being collectively looked at for an increasingly broad set of applications including photovoltaics, solid state lighting, power electronics and a broad class of flexible and wearable electronics. In this talk, we will focus on two main areas; the development of predictive models to be able to identify dopants and the processing regimes where they can be activated as well as the use of nanowire oxide composites to develop a new generation of tunable high performance TC. The complex set of demands for a desired TC include not only classical performance, but also processibility, cost and reliability necessitating a search for new materials. The ability to use materials genomics to identify new dopable TC materials that are experimentally realizable is rapidly increasing. We will discuss recent work on predicting the dopability of Ga2O3 films, which potentially have broad applicability as buffer layers, TCOs, and in power electronics if the doping level can be well controlled. We will discuss the theoretical predictions for the process windows to activate both Sn and Si as dopants and compare this to experimental results and the literature. We will also present resent results on the theoretical prediction and realization of a new p-type TC based on CuZnS, which has demonstrated conductivities of up to 100 S/cm. The latter while not classically an oxide is certainly non-stoichiometric and properties are enhanced in many cases by the use of complex oxide, sulfide and selenide materials. Together these will illustrate the evolving tools both theory and experiment to develop and realize dopants in wide band gap materials. In cases where single materials may not be sufficient, nanowire (metal or carbon based) composites with oxides is increasingly attractive. For example, Ag, and potentially Cu, nanowires embedded in a metal oxide matrix can potentially produce TCs that can be processed at low temperature, have conductivity and transparency comparable to the best TCOs, control interface stability and electronic properties and are suitable to flexible electronics. We will present work on ZnO, InZnO and ZnSnO composites with Ag nanowires where the performance can be as good as high quality InSnO with films Rs\u3c 10 Ohms/sq. We will discuss the dependence on the interrelationship between the nanowire properties and the oxide properties. We will also discus the concept of employing sandwich oxides to separately optimize the top and bottom interfacial properties. This work was supported, in part, by the Center for the Next Generation of Materials by Design, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences. This research also supported in part by the Solar Energy Research Institute for India and the U.S. (SERIIUS) funded jointly by the U.S. Department of Energy subcontract DE AC36-08G028308 (Office of Science, Office of Basic Energy Sciences, and Energy Efficiency and Renewable Energy, Solar Energy Technology Program, with support from the Office of International Affairs) and the Government of India subcontract IUSSTF/JCERDC-SERIIUS/2012 dated 22nd Nov. 2012