Corrosion and wear properties of multipurpose coatings deposited by ion-beam-assisted deposition

Electrochemical measurements and wear tests were performed on aluminium and aluminium alloy coatings containing magnesium for uniform and local pitting corrosion protection of low carbon steel substrates. Final hard chromium nitride and aluminium nitride layers were deposited at the surface of the protective films in order to lower friction and wear. The results show that wear and corrosion protection can be improved by use of bifunctional multilayers. The coatings for multipurpose application were generated by ion-beam-assisted deposition. The defined intrinsic film stress controlled by the ion-to-atom arrival ratio influences the corrosion properties. Increasing the ion-to-atom ratios usually improves the corrosion resistance.     

Rotating Heat Exchangers and the Optimization of a Heat Pump

Flow and heat transfer conditions are investigated on rotating flat plates and on blades of tangential blowers. The solution of the three dimensional boundary layer equations for rotating flat plates show that 3-D effects are of influence only in the neighborhood of the axis of rotation. The conditions outside this region can be treated as flow in a 2-D system. The measurements indicate that turbulent flow exists already at Re-values much smaller than Reclit for stationary flat plates. As a result of this, high heat transfer rates can be achieved at lower average velocities. All data taken on rotating flat plates and on the blades of a tangential blower can be correlated by a single dimensionless relationship. The results obtained by theory and measurements are used to derive design curves for the construction of a heat pump. A device built in accordance to these curves performed as predicted. Discussed are also rotating furnaces, radiators and condensers for vapor driven engines.     

Mass transfer at the gas evolving inner electrode of a concentric cylindrical reactor

Mass transfer coefficients for an oxygen evolving vertical PbO₂ coated cylinder electrode were measured for the anodic oxidation of acidified ferrous sulphate above the limiting current. Variables studied included the ferrous sulphate concentration, the anode height, the oxygen discharge rate and the anode surface roughness. The mass transfer coefficient was found to increase with increasing O₂ discharge rate,V, and electrode height,h, according to the proportionality expressionK V ^0.34 h ^0.2. Surface roughness with a peak to valley height up to 2.6 mm was found to increase the rate of mass transfer by a modest amount which ranged from 33.3 to 50.8% depending on the degree of roughness and oxygen discharge rate. The present data, as well as previous data at vertical oxygen evolving electrodes where bubble coalescence is negligible, were correlated by the equationJ=7.63 (Re. Fr)^–0.12, whereJ is the mass transferJ factor (St. Sc ^0.66).Notation a ₁,a ₂ constants - A electrode area (cm²) - C concentration of Fe²⁺ (M) - d bubble diameter (cm) - D diffusivity (cm² s^–1) - e electrochemical equivalent (g C^–1) - F Faraday's constant - g acceleration due to gravity (cm s^–2) - h electrode height (cm) - I _Fe ²⁺ current consumed in Fe²⁺ oxidation A - I _{o 2} current consumed in O₂ evolution, A - K mass transfer coefficient (cm s^–1) - m amount of Fe²⁺ oxidized (g) - P gas pressure (atm) - p pitch of the threaded surface (cm) - Q volume of oxygen gas passing any point at the electrode surface (cm³ s^–1) - R gas constant (atm cm³ mol^–1 K^–1) - r peak-to-valley height of the threaded surface (cm) - t time of electrolysis (s) - T temperature (K) - solution viscosity (g cm^–1 s^–1) - V oxygen discharge velocity as defined by Equation 3 (cm s^–1) - Z number of electrons involved in the reaction - Sh Sherwood number (Kd/D) - Re Reynolds number (Vd/) - Sc Schmidt number (v/D) - J mass transferJ factor (St. Sc ^0.66) - St Stanton number (K/V) - Fr Froude number (V ²/dg) - Solution density, g cm^–3 - v Kinematic viscosity (cm² s^–1) - bubble geometrical parameter defined in [31] - fractional surface coverage - diffusion layer thickness (cm)     

Mass-Balance Model of Pulmonary Oxygen Transport

A dynamic lumped-parameter model for pulmonary gas transport has been developed to characterize the lung and predict the effect of various parameter changes. The gas side of the lung is modeled as a series and parallel arrangement of five perfectly mixed, variable-volume compartments that correspond roughly to airway and alveolar regions. The blood side of the lung is modeled as a series of perfectly mixed, constant-volume compartments that represent the pulmonary capillary bed. From nonsteady mass balances, equations are derived which yield the time course of concentration for each compartment. Model simulations indicate that the oxygen-hemoglobin reaction does not reach equilibrium in the pulmonary capillaries, an assumption commonly made in analyses of pulmonary oxygen transport. Simulations also show the extent to which breathing amplitude and rate can affect the oxygen level in the blood leaving the lung. A comparison of simulations for a normal state and chronic obstructive lung disease (COLD) with identical input conditions demonstrates that the oxygen level in the blood leaving the lung is much lower in COLD. Also, the simulations are compared with experimental findings.     

Textile Applications of Adjustable-Frequency Drives with Digital Ratio Control

The application of digital techniques to program and to process the input signals to adjustable-frequency inverters for the control of rugged ac motors is becoming widespread. It was perhaps inevitable that digital signal control would eventually be combined with the inherently digital adjustable-frequency power inverter to produce systems having high overall line speed accuracy, adjustable ``digital gearing' between sections, locked-in-step acceleration from creep to run speed, and in-train digital jogging. A short introduction to adjustable-frequency motor control is given, and the use of digital techniques for controlling adjustable-frequency inverters to produce digital speed systems is described. Early applications of the first solid-state inverters to synthetic fiber spinning and their continued use is described. Specific current applications of digitally controlled adjustable-frequency speed systems are discussed, and potential applications that demonstrate how the capabilities of such systems can be used to provide economic solutions to many textile industry drive problems are reviewed.     

Environmental Control Symposium

MAN is but a part of the universe; his capabilities make him a significant link, in the cycle of life. To ensure this life, man must live in harmony with his environment. Recently, a disharmony has been discovered which could have grave effects upon the existence of man. It appears that man in his great thrust forward is destroying his own environment. The gravity of this threat to man's own existence carries some intrinsic problems of its own: man must allow his reason rather than his emotion to take command.     

A farm level approach to define successful mitigation strategies for GHG emissions from ruminant livestock systems

Ruminant livestock systems are a significant source of greenhouse gases (GHGs). Thus far, mitigation options for GHG emissions mainly focused on a single gas, and are treated as isolated activities. The present paper proposes a framework for a farm level approach for the full accounting of GHG emissions. The methodology accounts for the relevant direct and indirect emissions of methane, nitrous oxide and carbon dioxide, including carbon sequestration. Furthermore, the potential trade-off with ammonia volatilisation and nitrate leaching are taken into account. A ruminant livestock farm is represented with a conceptual model consisting of five pools: animal, manure, soil, crop and feed. The carbon and nitrogen inputs, throughputs and outputs are described, and the direct emissions are related to the carbon and nitrogen flows. The indirect emissions included in the methodology are mainly carbon dioxide emissions from energy use and nitrous oxide emissions related to imported resources and nitrogen losses. The whole farm approach is illustrated with a case of two dairy farms with contrasting livestock density and grassland management. It is shown that the inclusion of carbon sequestration and all indirect emissions have a major impact on the GHG budget of the farm. For one farm, the effect of four mitigation options on the GHG emissions was quantified. It was concluded that a whole farm approach of full accounting contributes to a better insight in the interactions between the carbon and nitrogen flows and the resulting emissions, within and outside the farm boundaries. Consequently, the methodology can be used to develop efficient and effective mitigation strategies.     

The Structure of the Irreversibly Bound Adhesion Promoter-Substrate Interfacial Layer of γ-Aminopropylsilanetriol on Crystalline Si, as Measured by XPS and FTIR

The irreversibly bound interfacial layer deposited by the γ-aminopropysilanetriol adhesion promoter onto a crystalline silicon substrate, which remains even after profuse washing, was found by XPS to have resulted from the fragmentation and rearrangement of the original γ-aminopropylsilanetriol molecule. A mechanism is proposed, involving the homolytic scission of the terminal N-C bond. One of the subsequent reactions is believed to involve hydrogen loss by abstraction and the formation of a terminal vinyl group, which bonds to the substrate. Support for this mechanism is found in IR spectroscopy of this layer.