Potential-time measurements on mild steel in etch primer solutions

Experiments were carried out in a two pack system; polyvinyl butyral, zinc tetroxychromate in one pack, and phosphoric acid in the other with an isopropanol solvent in both packs. This study examines the functions of the phosphoric acid and the chromate containing pigment separately by utilising the feature that the alcohol dispersed components have sufficient conductivity to carry out potential-time measurements in the wet components before and during mixing.     

Pollution by mites and/or mold spores in work environments and the risk of occupational respiratory pathology

In recent years the measurement of mold spore concentrations in working environments where workers spend long periods of time has acquired considerable importance because of the diffusion of diseases caused by fungi. On this basis, the aim of the research was to evaluate the level of environmental fungal pollution and contamination by mites in three factories producing seasoned foods, i.e., hams, sausages and cheeses. We also studied the occurrence of fungal species in the upper respiratory tract of workers operating in the washing and brushing areas, which was compared with the environmental concentrations in these areas, where contamination with fungal spores was visibly high. The results showed high and widespread fungal pollution in most of the working environments sampled and a significant presence of the same species in the upper respiratory tract of the workers. The data obtained indicate that the environments sampled can constitute a possible health risk factor for workers.     

Ripple evaluation of high-performance synchronous reluctancemachines

In this article, synchronous reluctance motors with multiple-segment rotor structures are considered. The presence of stator slots is taken into account, with respect to torque ripple. An analytical model is presented, based on magnetic interaction between the d and q axes, due to stator toothing. The effect of skewing is also considered, showing its partial effect on torque ripple reduction, due to the rotor anisotropy. A closed expression for the torque is obtained, giving the torque ripple as a function of design parameters. Experimental verification of the proposed model is given, from measurements on prototype motors     

The impact of cleaner processing on nutrient availability in the bleached kraft industry.

The pulp and paper industry has invested heavily over recent years in cleaner processing, to reduce losses and minimise its impact on the environment. Over the past fifteen years, a New Zealand integrated bleached kraft mill has undergone a comprehensive programme of upgrades to increase production, reduce water consumption and streamline its biological treatment process. Whilst the overall discharge of contaminants from the site decreased, the treatment system performance did not show a concurrent improvement as may have been expected. Reduced BOD removal, low dissolved oxygen levels, and poor solids settlability were symptomatic of phosphorus limitation in the aerated lagoon treatment system. The wastewater entering the system was found to be phosphorus limited at a BOD:P ratio of 100:0.2. Mono-ammonium-phosphate was supplemented, at approximately 30 kg P/d, to raise the phosphorus levels to a BOD:P ratio of 100:0.3. Treatment efficiencies improved very quickly after phosphorus dosage, with a 50% reduction in BOD and TSS discharge, a significant increase in dissolved oxygen levels, and improved BOD removal (85% to 93%). This case study demonstrates that whilst more closed operation can result in reduced discharge of organic loads, there may be negative impacts on the availability of nutrients for balanced biological growth.     

Simulation and experimental analyses of electromagnetic transients behaviors of lightning surge on vertical conductors

Simulation of very fast surge phenomena in a three-dimensional (3-D) structure requires a method based on Maxwell's equations, such as the finite-difference time-domain (FDTD) method or the method of moments, because circuit-equation-based methods cannot handle the phenomena. This paper uses a method of thin-wire representation of the vertical conductor system for the FDTD method which is suitable for the 3-D surge simulation. The thin-wire representation is indispensable to simulate electromagnetic surges on wires or steel frames in which the radius is smaller than a discretized space step used in the FDTD simulation. In this paper, a general surge analysis program named the virtual surge test lab based on the Maxwell's equations formulated by the FDTD method, is used to simulate the surge phenomena of a vertical conductor, including the effects of horizontal wave incidence and vertical wave incidence. Experimental results on the reduced scale model have been presented in order to compare among the simulation results by the FDTD method and the results using numerical electromagnetic code based on the MoM.     

Providing application-level QoS in 3G/4G wireless systems: a comprehensive framework based on multirate CDMA

The emerging applications for 3G and 4G wireless systems typically require highly heterogeneous and time-varying quality of service from the underlying protocol layers. The wireless links, however, provide only an unreliable communication channel that suffers from temporal outages. As a consequence, protocol mechanisms are needed that, based on the unreliable wireless links, provide the different service qualities required by the emerging applications. We identify the emerging IP-based applications for 3G and 4G wireless systems and categorize their QoS requirements. We discuss the wireless access mechanisms that show promise as the basis for supporting these applications. We then propose a set of protocol mechanisms that, based on the discussed wireless access mechanisms, provide the required QoS for the different application categories.     

Novel bipolar differential input/output current-controlled current source

A new bipolar differential input/output current-controlled current source (CCCS) is described. The basic cell consists of a translinear array of six transistors with two bipolar inputs, and is suited for the input stage of a differential current-mode operational amplifier.