A generic automated/semiautomated digital multi-electrodeinstrument for field resistivity measurements

The objective of this work is to design and test a digital multi-electrode acquisition system for use in geophysical investigations utilizing direct current electrical (geoelectric) methods. The system is a 64-electrode modular system, which utilizes field electrodes with individual wires that lead back to a digital switch box and then to a data acquisition instrument (Iris Syscal R2). The electronic design allows for different arrays or geometrical switching configurations of the field electrodes in order to allow for rapid data reading and yield essentially real-time results. Additionally, the electronic switch box has the capability to be connected in series to similar switch boxes and, therefore, has the ability to switch between an unlimited number of electrodes. The acquisition control software, developed as an interface for the hardware, controls operation of both the digital switch box and the resistivity acquisition instrument     

Solid Lipid Dispersions: Potential Delivery System for Functional Ingredients in Foods

Structured solid lipid (SL) systems have the advantages of long‐term physical stability, low surfactant concentrations, and may exhibit controlled release of active ingredients. In this research work, the potential use of high‐melting SLs for the production of the above structured SL carrier systems was investigated. Dispersions containing either SL or blend of solid lipid and oil (SL+O) were produced by a hot melt high‐pressure homogenization method. Experiments involved the use of 3 different SLs for the disperse phase: stearic acid, candelilla wax and carnauba wax. Sunflower oil was incorporated in the disperse phase for the production of the dispersions containing lipid and oil. In order to evaluate the practical aspects of structured particles, analytical techniques were used including: static light scattering to measure particle sizes, transmission electron microscopy (TEM) for investigating particle morphology and differential scanning calorimetry (DSC) to investigate the crystallization behavior of lipids in bulk and in dispersions. Results showed different mean particle sizes depending on the type of lipid used in the disperse phase. Particle sizes for the 3 lipids were: stearic acid (SL: 195 ± 2.5 nm; SL+O: 138 ± 6.0 nm); candelilla wax (SL: 178 ± 1.7 nm; SL+O: 144 ± 0.6 nm); carnauba wax (SL: 303 ± 1.5 nm; SL+O: 295 ± 5.0 nm). TEM results gave an insight into the practical morphology, showing plate‐like and needle‐like structures. DSC investigations also revealed that SL dispersions melted and crystallized at lower temperatures than the bulk. This decrease can be explained by the small particle sizes of the dispersion, the high‐specific surface area, and the presence of a surfactant.     

A Web-based electrical and electronics remote wiring and measurement laboratory (RwmLAB) instrument

This paper presents an instrument based on a new architecture called "Remote Wiring and Measurement Laboratory" ( RwmLAB) acting as a local multicircuit board on a common distributed panel on the Internet. Matrix switching, data acquisition, data processing and analysis, and graphical unit interface enabled-devices characterize the RwmLAB. RwmLAB is intended to address real-time remote wiring of electrical and electronic circuits and real data acquisition over the Internet instead of using simulated data. This Web-based instrument allows for flexibility and the spontaneous delivery of laboratory material and ensures a global access to a worldwide audience.     

Microprocessor-based sinusoidal waveform synthesis using Walsh andrelated orthogonal functions

A method is described of eliminating harmonics in a pulsewidth-modulated waveform using Walsh and related functions that substitute linear algebraic equations for the nonlinear equations required in Fourier-series harmonic elimination. A microprocessor can then be used to calculate the firing angles to cancel the unwanted harmonics. In an extension of the method, it is shown that a sine wave can be synthesized from a fixed-voltage DC supply by using a reasonable number of power electronic switches