Lead Telluride Doped with Au as a Very Promising Material for Thermoelectric Applications

PbTe single crystals doped with monovalent Au or Cu were grown using the Bridgman method. Far infrared reflectivity spectra were measured at room temperature for all samples and plasma minima were registered. These experimental spectra were numerically analyzed and optical parameters were calculated. All the samples of PbTe doped with Au or Cu were of the “n” type. The properties of these compositions were analyzed and compared with PbTe containing other dopants. The samples of PbTe doped with only 3.3 at% Au were the best among the PbTe + Au samples having the lowest plasma frequency and the highest mobility of free carriers-electrons, while PbTe doped with Cu was the opposite. Samples with the lowest Cu concentration of 0.23 at% Cu had the best properties. Thermal diffusivity and electronic transport properties of the same PbTe doped samples were also investigated using a photoacoustic (PA) method with the transmission detection configuration. The results obtained with the far infrared and photoacoustic characterization of PbTe doped samples were compared and discussed. Both methods confirmed that when PbTe was doped with 3.3 at% Au, thermoelectric and electrical properties of this doped semiconductor were both significantly improved, so Au as a dopant in PbTe could be used as a new high quality thermoelectric material

Improved Model of T-Type LC EMI Chip Filters Using New Microstrip Test Fixture

In this paper we present an improved model of the multilayered T-type electromagnetic interference chip LC filter for printed circuit board applications, and an improved measurement technique for characterization of such devices. Electrical parameters measurements of the same LC filter can vary for different measurement types. Because of that, we have developed new adaptation microstrip test fixture on printed circuit board for vector network analyzers' measurements of surface mount devices with three terminals. Two commercially available components, multilayer T-type LC filters, are measured and characterized using a vector network analyzer. The comparison of measurement data and simulation values of electrical equivalent circuit and electromagnetic model for two LC filters is further presented. The new improved model of T-type LC filters has provided better agreement between measurement and simulation

Mn-Zn Ferrite Round Cable EMI Suppressor With Deep Grooves and a Secondary Short Circuit for Different Frequency Ranges

A novel Mn-Zn ferrite round cable electromagnetic interference (EMI) suppressor with deep grooves and a secondary short circuit was constructed, realized and measured. Three steps were passed in novel suppressor development: from developing a suitable magnetic material, to constructing a suppressor device, to forming a new class of possible applications. Soft ferrite feedstock was formed from fine commercial Mn-Zn powder and a Solvent system binder based mainly on wax. Cylinder-shape cores with grooves were injected by powder injection molding (PIM) technology, chemically and thermally debinded and sintered at optimal conditions (1280 degrees C/2 h). The samples were aimed to serve as cores for EMI suppressors on cables. Their impedance versus frequency was measured using the core length as a parameter. After that, copper wire was placed into the grooves on the outside surface of cores to form a secondary coil and different configurations were considered. The contribution of the short circuit coil inserted into the grooves to EMI suppression was measured and analyzed also. Maximal impedance values can be achieved with a secondary short circuited winding which passes through every groove. It was also shown that ferrite cores of the same length could be used for different frequency ranges by changing the configuration of secondary short circuited windings

Analysis of a Mn–Zn Ferrite Bundle EMI Suppressor Using Different Suppressing Principles and Configurations

A novel round cable electromagnetic interference (EMI) suppressor comprising a bundle of Mn-Zn ferrite tubes was realized using different principles of suppressing, such as direct suppressing, inverting/suppressing, transform/inverting suppressing, and transform/short circuited secondary suppressing. Different primary to secondary configurations were realized for each suppressing principle and characterized in the EMI frequency region. The results obtained for different bundle configurations were compared with known commercial round cable ferrite suppressors and the initial bundle configuration made of a half turn wire through the central ferrite tube of the bundle. The results obtained for different principles and configurations were correlated in order to optimize the electromagnetic coupling between primary and secondary circuits. The values such as maximums of impedance Z(m), frequency of maximum impedance F-m and suppressing range Delta(f) around F-m calculated on 0.707 Z(m) were defined as the main parameters for each configuration. Certain correlations were noticed between impedance Z(m) and frequency F-m changes. Finally, the realized configurations were considered as devices suitable for EMI suppressing applications

The Response of a Heat Loss Flowmeter in a Water Pipe Under Changing Flow Conditions

A heat loss flowmeter for measuring the volume flow rate of water in real time (t) was formed using two thick film segmented thermistors, range constant voltage (RCV) power supply, acquisition card, PC, and software. The input water temperature T-w(t) was measured by a cold thermistor, while the water flow rate Q(t) was determined using the heat loss principle by measuring the self-heated thermistor current I(t). The flowmeter inertia, stability, and accuracy were measured and analyzed on a flowmeter prototype in real-time and real conditions on the water mains. The flowmeter response was measured for different durations of step input water flow-out functions and intervals between steps. An independent ultrasonic flowmeter was connected in series with the thermal flowmeter to measure the ordered input water flow functions. The realized intelligent functions in real time were: measuring the input water temperature T-w(t) and self-heating temperature T-s(t), auto-selection of RCV supply voltage U(Tw), determination and modeling of the water flow rate in real time Q(t), determination of the water volume V(t), and determination of the thermal gradient on the self-heating thermistor as a water flow indicator Delta Rs(t)