Radial Transmission Research Articles

Development of a novel compression tester and rheo-mechanical properties of wet-mass powder. II--Effect of moisture content on the rheo-mechanical properties.

In our previous paper [Watano S., et al., Chem. Pharm. Bull., 51(7), 747-750 (2003)], a novel compression tester, which enables the vertical and radial pressure transmission measurement, has been developed and quantitative analysis of rheo-mechanical properties of wet-mass powder prepared by different kneading times was conducted. In this study, the compression test was conducted by using the kneaded wet-mass powders prepared by different moisture contents. Pressure transmission characteristics and rheo-mechanical properties have been investigated to characterize the wet-mass powders. The relationship between these parameters and granule physical properties was also investigated.

System and method of assessing the structural properties of wooden members using ultrasound

A system and method of detecting anomalies and/or grain variations in a wooden member. At least one ultrasonic transmitter (401) applies an ultrasound waveform into a surface of a wooden member (100) so as to generate a multiplicity of ultrasonic waves including, e.g., longitudinal and shear waves. These ultrasonic waves are measured after propagation through the wooden member by at least one ultrasonic receiver (402) disposed on the same surface of the wooden member. At least one ultrasonic receiver (501) may also be placed opposite the ultrasonic transmitter (401) so as to detect radial transmission of the longitudinal ultrasonic wave at a point across the wooden member. The received ultrasonic waves are processed to determine anomalies and/or grain variations in the wooden member at positions of the wooden member between the ultrasonic transmitter and the ultrasonic receiver(s). The ultrasonic transmitters and receivers the ultrasound may be placed in rollers to facilitate high-speed, in-line processing of wooden members.

Correction to "Nonlinear analysis of disk resonators. application to material characterization and filter design"

A procedure for the numerical prediction of the microwave nonlinear behavior (intermodulation products, degradation of quality factors, etc.) of TM010 disk resonators has been developed. The procedure is based on relating a very general description of HTS nonlinearities with the circuit elements of a nonlinear radial transmission line. This radial transmission line is then analyzed using the harmonic balance algorithm. Successful cross-checks are performed by comparing simulations with theoretical results obtained for a specific model of HTS nonlinearity. The application of this procedure to the determination of nonlinear material parameters from disk resonator measurements is illustrated as well as its use for simulating filters with several inter-coupled disks. Correction: J. Mateu, IEEE Trans. Appl. Superconduct., vol. 11, pp. 135–138, Mar. 2001. On p. 137 of the above paper, the first sentence of the paragraph immediately following equation (14) should read as follows.

Basis for optimization of in vitro exposure apparatus for health hazard evaluations of mobile communications

The main objective of this paper is to carefully study the fields induced in flasks exposed to RF electromagnetic fields. The study focuses on the widely used 60 mm Petri dishes and rectangular T-75 flasks for the two following cases: 1) cells in homogeneous suspension and 2) cell monolayers. The dependence of the coupling and the homogeneity of the SAR distribution on frequency (0.7 GHz to 2.5 GHz), polarization (E, H and k polarizations) and the amount of medium (1.9 mm to 4.7 mm medium height) is studied. In addition, the effects of the environment, meniscus and field impedance as well as the distortion of the incident field are discussed. Based on these results, advantages and disadvantages of different fundamental designs of apparatus used in the past are compared. These are TEM cells, HF chambers, radial transmission lines (RTL), waveguides and wire patch cells. Furthermore, the major optimization parameters are identified for the development of highly optimized exposure systems, enabling the conduct of high quality experiments.

Chromosome damage and micronucleus formation in human blood lymphocytes exposed in vitro to radiofrequency radiation at a cellular telephone frequency (847.74 MHz, CDMA).

Peripheral blood samples collected from four healthy nonsmoking human volunteers were diluted with tissue culture medium and exposed in vitro for 24 h to 847.74 MHz radiofrequency (RF) radiation (continuous wave), a frequency employed for cellular telephone communications. A code division multiple access (CDMA) technology was used with a nominal net forward power of 75 W and a nominal power density of 950 W/m(2) (95 mW/cm(2)). The mean specific absorption rate (SAR) was 4.9 or 5.5 W/kg. Blood aliquots that were sham-exposed or exposed in vitro to an acute dose of 1.5 Gy of gamma radiation were included in the study as controls. The temperatures of the medium during RF-radiation and sham exposures in the Radial Transmission Line facility were controlled at 37 +/- 0.3 degrees C. Immediately after the exposures, lymphocytes were cultured at 37 +/- 1 degrees C for 48 or 72 h. The extent of genetic damage was assessed from the incidence of chromosome aberrations and micronuclei. The kinetics of cell proliferation was determined from the mitotic indices in 48-h cultures and from the incidence of binucleate cells in 72-h cultures. The data indicated no significant differences between RF-radiation-exposed and sham-exposed lymphocytes with respect to mitotic indices, frequencies of exchange aberrations, excess fragments, binucleate cells, and micronuclei. The response of gamma-irradiated lymphocytes was significantly different from that of both RF-radiation-exposed and sham-exposed cells for all of these indices. Thus there was no evidence for induction of chromosome aberrations and micronuclei in human blood lymphocytes exposed in vitro for 24 h to 847.74 MHz RF radiation (CDMA) at SARs of 4.9 or 5.5 W/kg.

Measurement of DNA damage in mammalian cells exposed in vitro to radiofrequency fields at SARs of 3-5 W/kg.

In the present study, we determined whether exposure of mammalian cells to 3.2-5.1 W/kg specific absorption rate (SAR) radiofrequency fields could induce DNA damage in murine C3H 10T(1/2) fibroblasts. Cell cultures were exposed to 847.74 MHz code-division multiple access (CDMA) and 835.62 frequency-division multiple access (FDMA) modulated radiations in radial transmission line (RTL) irradiators in which the temperature was regulated to 37.0 +/- 0.3 degrees C. Using the alkaline comet assay to measure DNA damage, we found no statistically significant differences in either comet moment or comet length between sham-exposed cells and those exposed for 2, 4 or 24 h to CDMA or FDMA radiations in either exponentially growing or plateau-phase cells. Further, a 4-h incubation after the 2-h exposure resulted in no significant changes in comet moment or comet length. Our results show that exposure of cultured C3H 10T(1/2) cells at 37 degrees C CDMA or FDMA at SAR values of up to 5.1 W/kg did not induce measurable DNA damage.

Developmental Inhibitory Gate Controls the Relay of Activity to the Superficial Layers of the Visual Cortex

A developmental reduction in the radial transmission of synaptic activity has been proposed to underlie the end of the critical period for experience-dependent modification in layers II/III of the visual cortex. Using paired-pulse stimulation, we investigated in visual cortical slices how the propagation of synaptic activity to the superficial layers changes during development and how this process is affected by sensory experience. The results can be summarized as follows. (1) Layers II/III responses to repetitive stimulation of the white matter become increasingly depressed between the third and sixth week of postnatal development, a time course that parallels the end of the critical period. (2) Paired-pulse depression is reduced after dark rearing and also by blocking inhibitory synaptic transmission. (3) Paired-pulse depression and its regulation by age and sensory experience is more pronounced when stimulation is applied to the white matter than when applied to layer IV. Together, these results are consistent with the idea that the maturation of intracortical inhibition reduces the capability of the cortex to relay incoming high-frequency patterns of activity to the supragranular layers.

Nonlinear analysis of disk resonators. Application to material characterization and filter design

A procedure for the numerical prediction of the microwave nonlinear behavior (intermodulation products, degradation of quality factors, etc.) of TM/sub 010/ disk resonators has been developed. The procedure is based on relating a very general description of HTS nonlinearities with the circuit elements of a nonlinear radial transmission line. This radial transmission line is then analyzed using the harmonic balance algorithm. Successful cross-checks are performed by comparing simulations with theoretical results obtained for a specific model of HTS nonlinearity. The application of this procedure to the determination of nonlinear material parameters from disk resonator measurements is illustrated as well as its use for simulating filters with several inter-coupled disks.

Complex gyrator circuit of three-port circulators using gyromagnetic resonators with six-fold symmetry

An important planar resonator for use in the design of commercial three-port circulators consists of a radial gyromagnetic region symmetrically loaded by six uniform or radial transmission lines. One possible model for this sort of junction is, in general, a six-port network with three-fold symmetry with three coupled ports and three short- or open-circuited ones. The development of the open-circuited parameters and the complex gyrator circuit of this arrangement is made particularly simple by taking advantage of the symmetry of the problem region. Its tracking solution is given special attention.

The effects of metronome breathing on the variability of autonomic activity measurements

Background: Many chiropractors hypothesize that spinal manipulation affects the autonomic nervous system (ANS). However, the ANS responses to chiropractic manipulative therapy are not well documented, and more research is needed to support this hypothesis. This study represents a step toward the development of a reliable method by which to document that chiropractic manipulative therapy does affect the ANS by exploring the use of paced breathing as a way to reduce the inherent variability in ANS measurements. Objective: To examine the hypothesis that the variability of ANS measurements would be reduced if breathing were paced to a metronome at 12 breaths/min. Setting: The study was performed at Parker College Research Institute. Eight normotensive subjects were recruited from the student body and staff. Methods: Respiration frequency was measured through a strain gauge. A 3-lead electrocardiogram (ECG) was used to register the electric activity of the heart, and arterial tonometry monitors were used to record the left and right radial artery blood pressures. Signals were recorded on an IBM-compatible computer with a sampling frequency of 100 Hz. Normal breathing was used for the first 3 recordings, and breathing was paced to a metronome for the final 3 recordings at 12 breaths/min. Fourier analysis was performed on the beat-by-beat fluctuations of the ECG-determined R-R interval and systolic arterial pressure (SBP). Low-frequency fluctuations (LF; 0.04-0.15 Hz) reflected sympathetic activity, whereas high-frequency fluctuations (HF; 0.15-0.4 Hz) represented parasympathetic activity. Sympathovagal indices were determined from the ratio of the two bandwidths (LF/HF). The coefficient of variation (CV%) for autonomic parameters was calculated ([average/SD] × 100%) to compare breathing normally and breathing to a metronome with respect to variability. One-way analysis of variance was used to detect differences. A value of P <.05 was considered statistically significant; all results are presented as average ± SD. Results: Three male and 5 female normotensive subjects were studied. Metronome breathing did not produce any significant changes in blood pressure for the left and right radial arteries, heart rate, or pressure pulse transmission time. Breathing to a metronome increased ECG-HF power (0.25 ± 0.07 vs 0.35 ± 0.09, P <.04), decreased ECG-LF/HF (1.08 ± 0.55 vs 0.57 ± 0.35, P <.05), and reduced the CV% for ECG-LF (47.6% ± 23.4% vs 23.8% ± 14.6%, P <.03), ECG-HF (46.2% ± 14.2% vs 25.8% ± 17.0%, P <.03) and ECG-LF/HF (50.1% ± 27.6% vs 23.4% ± 12.3%, P <.03) in comparison with normal breathing. Metronome breathing increased the left and right radial artery SBP-HF fluctuations (left, 0.11 ± 0.05 vs 0.30 ± 0.16, P <.007; right, 0.09 ± 0.05 vs 0.27 ± 0.15, P <.008) and decreased the SBP-LF/HF components (left, 3.42 ± 2.36 vs 1.14 ± 0.88, P >.03; right, 3.08 ± 1.77 vs 1.20 ± 0.93, P <.02). Metronome breathing did not significantly alter the CV% for SBP-HF, SBP-LF, and SBP-LF/HF. Conclusions: Metronome breathing increased parasympathetic activity, as evidenced by augmented HF power in the ECG and SBP data. The variability (CV%) of ECG-determined ANS measurements was significantly reduced with paced breathing at 12 breaths/min, but no significant reductions were observed for the SBP-determined ANS measurements. These findings indicate that ECG data are more sensitive than SBP data for future clinical trials. (J Manipulative Physiol Ther 2000;23:610-4)

Electromagnetic torque of a synchronous machine during a single out‐of‐phase reclosing

AbstractThe adoption of single‐pole switching for a radial transmission line which connects large synchronous machines to the power system would submit these machines to repetitive mechanical stress. To evaluate the total mechanical stress, it is first necessary to determine the electromagnetic torque and to evaluate its transient maximum values at reclosing. In this paper, maximum values of the electromagnetic transient torque at single‐pole reclosing are first computed using a simplified analytical approach. The analytical results are then validated by numerical simulations and by an experimental test on a laboratory synchronous machine. It will be shown that single‐pole reclosing would be, in the worst case, as restricting as three out‐of‐phase synchronisation.

Experimental and numerical determination of SAR distributions within culture flasks in a dielectric loaded radial transmission line.

The effect of dielectric loading on the cell layer specific absorption rate (SAR) within a T-75 culture flask being irradiated within a transverse electromagnetic (TEM) cell was studied both experimentally and numerically. Direct thermal measurements of a T-75 containing 40 mL of culture medium and resting upon a 3-mm-thick slab of alumina ceramic (epsilon r = 9.6) revealed that, compared to the same flask resting upon a foam slab (epsilon r = 1.0) of the same thickness, the average SAR at the cell layer was increased roughly fourfold. This fourfold increase is significant experimentally because it allows biologists to perform experiments over a larger range of SAR values needed to determine possible dose-response curves without the costs and difficulties of a fourfold increase in amplifier power. Finite-difference time-domain (FDTD) simulations of the SAR distribution were in good quantitative agreement with the experimental measurements. It is concluded that FDTD modeling can be a cost effective and scientifically acceptable means of obviating the thermal measurement of SAR.

ARCH BRIDGE CROSSING THE BRNO-VIENNA EXPRESSWAY.

Keywords BRNO TECHNICAL UNIVERSITY, STRASKY HUSTY DOSTA BRNO BRIDGES, ARCHES, EXPRESSWAYS, ROADS, STEEL, CONCRETE, TUBES, INTEGRATED, PRESTRESSED, DECKS, SINGLE, STRUCTURES, SUPPORTS, CROSSINGS, AESTHETICS, DESIGN, CONSTRUCTION, FINITE ELEMENTS, METHODS, STRESS, DISTRIBUTION, MEMBERS, SKEW, STRUTS, POST TENSIONED, FOUNDATIONS, RESISTANCE, LOADS, HYBRID, MOTORWAYS BRNO, VIENNA, RAJHRAD CZECH REPUBLIC, EUROPE... Show All

A coaxial-radial line junction with a top loading disk for broadband matchings

A new coaxial)radial transmission-line junction is pro- posed and characterized by a rigorous full-wae modal-expansion method. The proposed structure modifies the conentional coaxial)radial junc- tion by introducing a circular disk on the top plate of the radial transmission line whose parameters can be adjusted for broadband matchings. Two examples are presented to demonstrate the junction's practicality. Q 1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 22: 87)90, 1999.

Analysis of die compaction of tungsten carbide and cobalt powder mixtures

This paper investigates die compression of tungsten carbide–cobalt powder mixtures, which is an important step in the processing route of cemented carbides. Simple action compression of miscellaneous mixtures has been investigated with an industrial type press allowing measurement of the force applied on both upper and lower punches. In addition, an original apparatus was used to measure the average radial stress applied upon the die, and the frictional shearing force at the powder/die interface was determined through a powder/wall friction apparatus. A mechanical analysis of the data obtained for various tungsten carbide–cobalt powder mixtures provided the intrinsic stress v. density compressibility relation as well as the radial stress transmission coefficient and the powder/die friction coefficient. In this framework, the effect of several material and process parameters on the densification is discussed.

PWM-controlled series compensation on a radial feed power system

A series compensation scheme is described employing two pulse width modulation (PWM) switched reactor modules in parallel with a capacitor. The two-module PWM-switched reactors provide continuously variable reactance by employing simple duty ratio control. The switching instants of the two reactor modules are controlled to have 180° phase shift, but equal duty ratio, to achieve harmonic cancellation. The complete series compensator provides a wide range of capacitive and inductive compensation. The harmonic distortion produced by this series compensation scheme with multiple-controlled reactors is analysed. An experimental model of the proposed compensator has been constructed and tested; this was inserted in a radial feed transmission line, to reduce the level of fluctuation of the receiving power on a nominal load subjected to another large load switching. For the two-module system, the voltage harmonics have been found to be well below the IEEE 519-1992 recommended limit, with a switching frequency of only 300 Hz. At the same time, the influence of the large load switching can be significantly reduced by the application of this compensator. The simplicity of the scheme and the quality of the results indicates its potential as another useful power quality controller.

The radial transmission line as a broad-band shielded exposure system for microwave irradiation of large numbers of culture flasks.

The problem of simultaneously exposing large numbers of culture flasks at nominally equivalent incident power densities and with good thermal control is considered, and the radial transmission line (RTL) is proposed as a solution. The electromagnetic design of this structure is discussed, and an extensively bench-tested realization is described. Referred to 1 W of net forward power, the following specific absorption rate (SAR) data were obtained: at 835.62 MHz, 16.0+/-2.5 mW/kg (mean+/-SD) with range (11-22); at 2450 MHz, 245+/-50 mW/kg with range (130-323). Radio-frequency interference from an RTL driven at roughly 100 W is so low as to be compatible with a cellular base station only 500 m distant. To avoid potential confounding by temperature differences among as many as 144 T-75 flasks distributed over 9 RTLs (six irradiates and three shams), temperature within all flasks was controlled to 37.0+/-0.3 degrees C. Experience with over two years of trouble-free operation suggests that the RTL offers a robust, logistically friendly, and environmentally satisfactory solution to the problem of large-scale in vitro experiments in bioelectromagnetics.

Evaluation of LEMP effects on complex wire structures located above a perfectly conducting ground using electric field integral equation in time domain

In this paper, a novel approach for the implementation of scattering theory is proposed in order to evaluate the electromagnetic effects of lightning return stroke on complex wire structures (lightning EM pulse - LEMP). An electric field integral equation (EFIE) in the time domain is employed to describe the electromagnetic transients from lightning. The proposed approach is applied to a single-phase, three-phase as well as a Y-shaped transmission line located above a perfectly conducting ground. The simulation results reproduce accurately experimental data available in the literature. The proposed method provides new possibilities in estimation of lightning indirect effects on complex networks as an example "radial transmission systems tapped from main switching substations" are investigated.

A Study on the Impedance Characterisation of Radial Transmission Line to Explain the Properties of Millimeter Wave 35-GHz Resonant-cap Impatt Oscillators

A band of frequencies around 35 GHz has found widely increasing use as an low attenuation window in communication, tracking radars and military purposes. A study of the impedance variation around 35 GHz at the centre of a radial transmission line with respect to its geometrical parameters is presented here. The variation of the resistance and reactance may be useful in explaining the properties of a millimeter wave 35 GHz resonant cap Impatt oscillator. The results have been compared with the experimental results and a qualitative agreement has been reached.

Measurement of DNA Damage after Exposure to Electromagnetic Radiation in the Cellular Phone Communication Frequency Band (835.62 and 847.74 MHz)

Mouse C3H 10T1/2 fibroblasts and human glioblastoma U87MG cells were exposed to cellular phone communication frequency radiations to investigate whether such exposure produces DNA damage in in vitro cultures. Two types of frequency modulations were studied: frequency-modulated continuous-wave (FMCW), with a carrier frequency of 835.62 MHz, and code-division multiple-access (CDMA) centered on 847.74 MHz. Exponentially growing (U87MG and C3H 10T1/2 cells) and plateau-phase (C3H 10T1/2 cells) cultures were exposed to either FMCW or CDMA radiation for varying periods up to 24 h in specially designed radial transmission lines (RTLs) that provided relatively uniform exposure with a specific absorption rate (SAR) of 0.6 W/kg. Temperatures in the RTLs were monitored continuously and maintained at 37 +/- 0.3 degrees C. Sham exposure of cultures in an RTL (negative control) and 137Cs gamma-irradiated samples (positive control) were included with every experiment. The alkaline comet assay as described by Olive et al. (Exp. Cell Res. 198, 259-269, 1992) was used to measure DNA damage. No significant differences were observed between the test group exposed to FMCW or CDMA radiation and the sham-treated negative controls. Our results indicate that exposure of cultured mammalian cells to cellular phone communication frequencies under these conditions at an SAR of 0.6 W/kg does not cause DNA damage as measured by the alkaline comet assay.