Applicability of Measurements of Local Electrical Parameters in the Modeling of Technological Texture of Ceramic Blanks

The paper deals with the modeling of the technological texture of the pressed ceramic materials in the radial and axial direction, which consists in the graphical representation and subsequent analysis of the distribution of the electrostatic field potential differences on the surface of the dielectric sample with the diameter d and the thickness h located between the electrodes. In occasion of observing radial texture the electrodes have the cylindrical configuration and in occasion of observing the axial texture in the sample the electrodes have the axial configuration. The theoretical relationship in the paper is derived for the calculation of the voltage values measured at any position between the center electrode and the peripheral electrode, at a constant voltage U applied to the outer and inner electrodes of the dielectric sample of thickness h of the raw ceramic sample material (radial texture). Measurements have demonstrated the suitability of identifying the technological texture by measuring the potential differences on the sample surface which is located between the electrodes in the relation to the technology preparation and to the quality of the fired ceramic production.

Ion Beam Emission within a Low Energy Focus Plasma (0.1 kJ) Operating with Hydrogen

An investigation of energetic ion beam emission from a low energy plasma focus (0.1 kJ Mather type) device operating with hydrogen gas is studied. The ion beam emission is investigated using time-integrated and time-resolved detectors. The present plasma focus device is powered by a capacitor bank of 1 μF at 18 kV maximum charging voltage. The correlation of ion beam intensity with filling gas pressure indicates that the beam emission is maximized at the optimum pressure for the focus formation at peak current. Energy of ions is determined with a time-of-flight (TOF) method, taking into account distance from the center electrode to the detection plane.

Electrostatic Capture of Airborne Nanoparticles in Swirling Flows for Bio-MEMS Applications

Motivated by capture and detection of airborne biological agents in real time, we present the electrostatic capture of 100nm diameter polystyrene nanoparticles as a model system under swirling gas flows in a homemade particle collector having the forward outlet. The particle collector has five small positive electrodes on the bottom and one large grounded electrode on the top. The particles coming into the collector are slowed down during their swirling and stay in the collector before leaving. Particles captured on the center electrode of this collector were much less than those on the surrounding four electrodes and 10 - 25% of the particles with negative charges entering this collector were captured on the bottom electrodes at a flow rate of 1.1 l/min and an applied potential of 2 kV. Using a commercial CFD code FLUENT, we simulated the effects of the different types of collector outlet configurations and flow rates on the particles' trajectories, velocities, and travel times inside the collector. We also present the highest particle capture position inside the collector in those different configurations. The forward outlet configuration is the most favorable to particle capture among the tested configurations in terms of particles' minimum achievable velocities and their travel times at a flow rate of 1.1 l/min. This collector is well adaptable to integration with micro resonator devices and can be used for real-time monitoring of bioaerosols.

Characterization of Erosion Mechanisms of Natural Gas Engine Spark Plugs

J-type spark plugs composed of Ni-base alloy electrodes with a pure Ir tip in the center electrode and a Pt-W alloy tip in the ground electrode were examined as-manufactured and after use in natural gas reciprocating engines by spectroscopic and metallurgical techniques. The spectroscopic examination indicated Ni emission from the Ni alloy electrodes in new plugs, but a strong Ca signal in engine used plugs. This was confirmed by metallurgical examination, which showed the presence of Ca containing glassy oxide phase(s) (with the electrode alloy components) in the used spark plug electrodes. Intergranular cracking was observed on the Ir and Pt-W alloy electrode insert tips. The interface between the Pt-W insert and the Ni alloy ground electrode also became a site for extensive cracking and oxidation during service. These oxidation/corrosion and metallurgical issues may represent a significant component of the wear mechanism of these plugs in natural gas engines.

Micromachined DNA Manipulation Device Using Circular Multi-Electrode

Microfabricated DNA manipulation devices have a wide range of potential applications. In this paper, we present a new concept for efficient biological reaction and a DNA manipulation device with the reaction chamber, which consists of a center electrode and circular outer electrodes of a reaction unit. We verified the DNA manipulation concept by numerically simulating its operation, and experimenting with the fabricated device. This proposed complex micro reaction or micro analytical systems are generally composed of various components with different functionality within the micro DNA manipulation system. 2cm Square, entirely monolithic device has been fabricated with reaction chamber, circular type electrode, microfabricated heater and sensor. In the suggested reaction system, the charged bio-molecules, DNA, are manipulated by the charge of the electrode in a reaction unit. Controlling the induced dynamic electric field between the center electrode and the outer electrodes, Concentration (+2V) / Repulsion (−2V) / Manipulation (+1V∼−1V) of bio-molecules are enabled at a periphery of electrode. It has no moving parts, physically constructed wall and can be built in a disposable unit of micro devices, which can be fabricated by conventional MEMS technique at low cost. Moreover, we evaluate temperature control unit characteristics for biological analysis such as PCR (Polymerase Chain Reaction), isothermal reaction temperature control. The coefficient of temperature heat resistance and heater temperature characteristic is about 0.0043 and 100°C/sec, respectively.

Spatial and Temporal Profiles of Indium in a Furnace Atomization Plasma Excitation Spectrometry Source

Spatially resolved emission and absorption intensities from the indium 303.94-nm resonance line were measured in a furnace atomization plasma excitation spectrometry (FAPES) source. These measurements show that the spatial structure observed in the analyte emission is due to two effects. The first is the spatial distribution of analyte atoms in the source. The absorption measurements show that this spatial distribution is fairly uniform. There is a slight gradient, with analyte concentrations increasing from the cuvette wall to the center electrode. The fine structure in the emission intensity profiles must therefore be caused by the dependence of the degree of analyte excitation on position within the cuvette. This structure suggests that the FAPES source operates as an atmospheric-pressure radio-frequency glow discharge. Negative glows are seen adjacent to the graphite cuvette wall and center electrode.