Adrian Ieta

Triboelectric charging between polytetrafluoroethylene and metals

Measurements were obtained on charge exchange processes occurring between small metal ballistic pellets and a polytetrafluoroethylene (PTFE) tube. Lead pellets of 5.5-mm diameter were propelled at a range of speeds through PTFE tubes of different lengths by compressed carbon dioxide. The charge incurred by the pellets and the tube was compared with the charge observed on copper and lead spheres rolled through the tube, driven by gravity. In all experiments, the charge on the moving pellet was measured with a Faraday cup. The experiments determined the effect of pellet speed on the magnitude of the charge accumulated on the pellet and on the PTFE tube. Sectioned shielding on the PTFE tube allowed the determination of surface charge distribution along its length by means of an electrometer. It was observed that the charge also depended on the work functions of the materials involved (lead, copper, PTFE). The charge on the pellets was found to range from +0.5/spl times/10/sup -8/ to +3.0/spl times/10/sup -8/ C, for pellet speeds from 10 to 80 m/spl middot/s/sup -1/. The reproducibility of results is discussed and comment provided on the degree of charge imbalance observed.

Fe-EDTA Thermal Decomposition, a Route to Highly Crystalline Hematite (Alpha Fe2O3) Nanoparticle Synthesis

In this study, we develop an experimental procedure to synthesize hematite nanoparticles by hydrothermal decomposition of Fe-EDTA complex in the presence of hydrogen peroxide, starting from ferric ammonium sulfate and Na 4 EDTA as main precursors. The product was investigated by X-ray diffraction, scaning electron microscopy, dispersive X-ray spectroscopy, magnetic measurements, and UV-vis optical absorption measurements. The size of nanoparticles was determined to be 42 nm evaluated by XRD patterns using the Scherrer equation. This method allowed the formation of pure hematite nanoparticles with good and stable crystallographic characteristics. This procedure can be an effective method for synthesizing hematite nanoparticles exhibiting good crystallinity, stoichiometry, magnetic, and optical band gap properties. A possible mechanism for the formation of hematite nanocrystals was suggested.

Panel - reforming mathematics requirements for a modern engineering education

The need for reform in undergraduate engineering curricula has been recognized in recent years. One important and vital aspect of such a reform concerns preparatory mathematics in engineering education and the revision of mathematics content in a modern engineering curriculum, the topic of this panel session. It has become increasingly obvious that the standard series of three calculus courses followed by one course on differential equations is now obsolete and insufficient to provide needed mathematical skills for a modern engineering education. ABET now requires discrete mathematics and applied statistics among other topics. Newly developed engineering programs have adopted different mathematics courses in their degree programs. A new electrical and computer engineering program is under development at the State University of New York at Oswego where a modern engineering curriculum must also face the challenge of smooth integration within the existing traditional curricular organization of a public university. The panelists will discuss the evidence in support of reform and engage discussions on directions, course content, and other issues for a successful revision of engineering education.

Scaling Law for Electrospray Droplet Formation

There has been a lot of research on liquid atomization by means of electrospray, particularly because of its many practical applications. Nevertheless, full understanding and control of the electrospray mechanisms are still incomplete. An experimental setup was developed in order to investigate the frequency characteristics of droplet formation and ejection at the tip of Taylors cone of aqueous electrosprays. Droplet formation and oscillations were monitored using a Kodak Ektapro high-speed camera. The frequency of droplet formation at the tip of the capillary needle was analyzed. Droplet frequency formation appears to exhibit three distinct regimes with an abrupt transition from one regime to another. Droplet formation was recorded at different needle-plate electrode distances. Based on the analysis of experimental data a scaling law for droplet formation was found.

Corona “impedance” in a pin-to-plane geometry

Abstract Our work focuses on the analysis of binary hydrocarbon mixtures, namely cyclopentane, 1-pentene and pentane. The purpose is to describe, analyze, and model the conduction properties of selected hydrocarbons, as well as to find a method for modifying the composition of hydrocarbon mixtures in order to obtain the desired discharge properties. Data analysis is performed in terms of the corona “ impedance ” of the discharge medium. In a logarithmic coordinate system, experimental data show a first-order dependence of the corona “ impedance ” of the electrode gap on the corona current, which appears to be more general in nature. Starting from a conic approximation of the geometry of the effective discharge area, we have derived a model where the mentioned linearity can be reduced to an expression that closely matches experimental data.

A short route of micrometric magnetite synthesis via Fe-EDTA thermal decomposition

We develop an procedure for synthesizing micrometric magnetite crystals after two hours of autoclavation at 250°C by hydrothermal decomposition of Fe- Ethylenediaminetetraacetic acid (Fe-EDTA) complex in the presence of urea starting from Fe (III)-Ferric Ammonium Sulfate (FAS), and Na4EDTA as main precursors. Crystals with 10–15 µm in size (along the <001> axis), were obtained. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy and magnetic measurements were performed to investigate the final product. A low remanent magnetization (5 emu/g) was observed at high level magnetic field intensity (3.8 kOe), emulating superparamagnetic behavior, uncommon for magnetic microparticles at room temperature.

Affective State Control for Neuroprostheses

The control and communication in man and the machine has been an active area of research since the early 1940s and since then the usage of the computing machine for the enhancement, augmentation, and rehabilitation of mankind has been broadly investigated. One active area of such research is the interface of the human brain to the computer; brain-computer-interfacing (BCI) or neuroprostheses. Current examples of functional BCI typically control the computer screen cursor movement, but require extensive subject training and significant, if not full, cognitive focus. Our model proposed an alternative approach to implementing the BCI for the application of controlling a digital hearing aid by autonomously modifying the speech signal based on the identification of electrophysiological response, or an affective state. Using a support vector machine binary classifier our model successfully demonstrated the efficacy of single-trial identification of affective states as an enhanced method of hearing neuroprosthetic control at a communication transfer rate of 240 bits/minute

Superparamagnetic Unusual Behavior of Micrometric Magnetite Monodisperse Monocrystals Synthesized by Fe-EDTA Thermal Decomposition

We developed a new procedure for synthesizing micrometric magnetite by hydrothermal decomposition of the Fe-EDTA complex in the presence of urea, starting from Fe(III)-ferric ammonium sulfate and Na4EDTA as main precursors. Microcrystals with superparamagnetic behavior with 25–45 μm in size were obtained (5 emu/g at 3.8 kOe magnetic field).

Highly Crystalline FeCO3 Microparticle Synthesis by Hydrothermal Decomposition of Fe‐EDTA Complex

In this article, we present an experimental procedure to synthesize highly crystalline FeCO3 by hydrothermal decomposition of Fe(III)‐EDTA complex, starting from Ferric Ammonium Sulfate and Na4EDTA main precursors in urea presence. The structure, morphology and composition of the powders were obtained using X‐ray powder diffraction and scanning electron microscopy. The peaks were founded, indicate that the synthesized products autoclaved 22 h at 250 °C are pure FeCO3, which was well proved experimentally from EDAX further investigated. The size with appreciatively 100 μm was evaluated by SEM images. Magnetic characterization confirmed the magnetic characteristics of FeCO3. This procedure allowed the FeCO3 microparticles formation with good and stabile crystallographic characteristics.

Onset Characteristics of Aqueous Large Gap Electrosprays

Electrosprays (ESs) have a wide variety of applications. In particular, the onset voltage parameter is of special interest. Our study investigated onset characteristics of aqueous ESs in a negative polarity for capillary tip-plate distances in the range of 0.5-50 cm. Experiments show significant variation of onset voltage with the presence of metal objects in the proximity of the ES. Data analysis shows an increase in onset voltage with the decrease in counterelectrode radius. The region least sensitive to such variation was found for tip-plate distances larger than 20 cm. Onset voltages appear to be in agreement with Smiths formula for a certain range of the distance studied. Gaps larger than 25 cm have generally shown more significant variations of this formula. The results of the present study can be useful for the design of ESs of larger gaps.