Electrical Echo Research Articles

Optimization of Left Ventricle Pace Maker Location Using Echo-Based Fluid-Structure Interaction Models.

IntroductionCardiac pacing has been an effective treatment in the management of patients with bradyarrhythmia and tachyarrhythmia. Different pacemaker location has different responses, and pacemaker effectiveness to each individual can also be different. A novel image-based ventricle animal modeling approach was proposed to optimize ventricular pacemaker site for better cardiac outcome.MethodOne health female adult pig (weight 42.5 kg) was used to make a pacing animal model with different ventricle pacing locations. Ventricle surface electric signal, blood pressure and echo image were acquired 15 min after the pacemaker was implanted. Echo-based left ventricle fluid-structure interaction models were constructed to perform ventricle function analysis and investigate impact of pacemaker location on cardiac outcome. With the measured electric signal map from the pig associated with the actual pacemaker site, electric potential conduction of myocardium was modeled by material stiffening and softening in our model, with stiffening simulating contraction and softening simulating relaxation. Ventricle model without pacemaker (NP model) and three ventricle models with the following pacemaker locations were simulated: right ventricular apex (RVA model), posterior interventricular septum (PIVS model) and right ventricular outflow tract (RVOT model). Since higher peak flow velocity, flow shear stress (FSS), ventricle stress and strain are linked to better cardiac function, those data were collected for model comparisons.ResultsAt the peak of filling, velocity magnitude, FSS, stress and strain for RVOT and PIVS models were 13%, 45%, 18%, 13% and 5%, 30%, 10%, 5% higher than NP model, respectively. At the peak of ejection, velocity magnitude, FSS, stress and strain for RVOT and PIVS models were 50%, 44%, 54%, 59% and 23%, 36%, 39%, 53% higher than NP model, respectively. RVA model had lower velocity, FSS, stress and strain than NP model. RVOT model had higher peak flow velocity and stress/strain than PIVS model. It indicated RVOT pacemaker site may be the best location.ConclusionThis preliminary study indicated that RVOT model had the best performance among the four models compared. This modeling approach could be used as “virtual surgery” to try various pacemaker locations and avoid risky and dangerous surgical experiments on real patients.

Automatic Distance and Angle Measurement Tool using Atmega8535 Microcontroller based Ultrasonic Sensor for Conventional X-Ray Medical Device

The aim of this research is to design an ultrasonic distance and angel detecting device by utilizes time delay of wave reflected. The ultrasonic echo waves were then converted into electrical echo pulses. This distance and angle detecting device can later be used on conventional X-ray modality. This distance and angle detecting device was designed based on ultrasonic sensor and an Atmega8535 microcontroller. Distance measurements was carried out vertically and horizontally with variations ranging from 90 cm to 130 cm with a 10 cm increment factor. While angle measurements were performed manually at angle variations of 10 ° to 30 ° with an increment factor of 5 °. The performance of the tool showed that the relative error value on vertical measurement was 0.10% with the greatest accuracy of 99.97%. While the horizontal measurement relative error was 0.10% and the highest relative accuracy recorded at 99.97%. Meanwhile, on the angle measurement, it was found that the relative error was0.39% with the highest relative accuracy of 99.72%.

Preliminary study on the separation of specular reflection and backscattering components using synthetic aperture beamforming

In the early stages of atherosclerosis, the luminal surface of the arterial wall becomes rough due to injury and detachment of endothelial cells. This roughening can potentially be estimated with ultrasound since the electrical echo signal from the transducer is sensitive to both the angle of incidence to an extended surface as well as the roughness of the surface. Specifically, as the roughness of an interface increases, specular reflection is substituted by scattering. We propose a method that attempts separation of reflection and backscattering components in the received echo signals. Assuming the predominant propagation directions of the reflected and scattered waves can be somewhat controlled by the emitted sound field, separation of those components was attempted using synthetic aperture imaging with a transmit beam, focused at a point more distant than the imaging depth. Specifically, two dedicated beamforming processes were used for generation of reflection-emphasized and backscattering-emphasized images. Experimental verifications on a phantom using an ultrasound system with a limited number of active transmit-receive channels yielded a difference between these two images of 8dB. The results further showed a similar (slightly improved) lateral spatial resolution size of 0.41mm for the backscattering-emphasized image compared with conventional B-mode imaging (0.47mm). A new technique for separation of the reflection and backscattering components using synthetic aperture beamforming with a transmit beam featuring a large focal distance was proposed. The technique demonstrated a partial separation of the reflection and backscattering components, which potentially may be used to estimate surface roughness.

FiniteAmplitude Power Budget Equations for Acoustic Fish Abundance Estimation

Finiteamplitude (nonlinear) sound propagation effects in seawater may cause measurement errors in fish and zooplankton abundance estimation and species identification for accessible echo sounder transmit electrical power levels and operating frequencies of about 100 kHz and higher. A sufficiently validated framework to quantify, control, and compensate for such errors in these applications is not available. The conventional power budget equations in fisheries acoustics are valid for smallamplitude signals only. The study aims to fill this “gap”. The conventional theory is generalized to account for finiteamplitude incident sound propagation, arbitrary electrical termination, and the range of electrical and acoustical echo sounder parameters. Equations for use in calibration and oceanic surveying are derived in terms of the backscattering cross section,, and the volume backscattering coefficient,. The “finiteamplitude terms” in these expressions can—for relevant transmit electrical power levels of relevant echo sounders—be measured in controlled tank experiments. Alternatively, they can be calculated using numerical models. The resulting equations enable estimation of finiteamplitude measurement errors in these applications; development of recommended upper limits for echo sounder power levels; controlled reduction of finiteamplitude errors in calibration and surveying; and development of correction factors for survey data already subjected to such measurement errors.

Echo-Based FSI Models to Simulate Ventricular Electrical Signal Conduction in Pig Pacemaker Models

Cardiac pacing has been an effective treatment in the management of patients with arrhythmia. Different pacemaker location may have different impact on pacemaker effectiveness. A novel image-based ventricle animal modeling approach was proposed to integrate echocardiography images, propagating dynamic electric potential on ventricle surface to perform myocardial function assessment. The models will be used to simulate ventricular electrical signal conduction and optimize pacemaker location for better cardiac outcome. One health female adult pig weight 42.5kg was used to make pacing animal model with different ventricle pacing locations. Pig health status was assessed before undergoing experimental procedures. Ventricle surface electric signal, blood pressure and echo image were acquired 15 minutes after the pacemaker was implanted. Echo-based left ventricle (LV) fluid-structure interaction (FSI) models were constructed to perform ventricle function analysis and investigate impact of pacemaker location on cardiac outcome. The nonlinear Mooney-Rivlin model was used for ventricle tissue material model. With the measured electric signal map from the pig associated with the actual pacemaker site, electric potential conduction of myocardium was modeled by material stiffening and softening in our model, with stiffening simulating contraction and softening simulating relaxation. Material stiffness parameters were adjusted in a cardiac cycle to match Echo-measured LV deformation and volume variations. Mapping between material stiffness and ventricle electric signal was quantified using data measured from the animal with different pacemaker locations. Ventricle model without pacemaker and three ventricle models with the following pacemaker locations were simulated: right ventricular apex (RVA), posterior interventricular septum (PIVS) and right ventricular outflow tract (RVOT). Data for ventricle volume change, ejection fraction, stress and strain, flow velocity and shear stress data were collected for comparisons. Our results demonstrating that PIVS pacing model had higher peak flow velocity and stress/strain. It indicated that PIVS pacemaker site may be the best location. This modeling approach could be used as “virtual surgery” to try various pacemaker locations and avoid risky and dangerous surgical experiments on real patients.

ELECTRO-ACOUSTIC PROBE BROADBAND EAR ECHO-SPECTROMETER FOR SCREENING OF HEARING OF NEWBORNS

The article presents the calculation and analysis of the earing echo-spectrometer: tube, horn, the phone choice rationale, also the signal processing algorithm is described in article. The main advantage of the developed method over other methods of objective human hearing diagnostic is grounded./p>In the since works there were attempts to create auditory sound methodology. The authors used a measuring circuit the complex impedance. However, the main concern of their research concluded that it was not satisfied the main condition of echolocation: the availability of sufficient spatial framework for the separation of the emitted and reflected pulses. Instead, it was mentioned the delay in the electric echo signal.The relevance of the present work is the developed method which allows to make the diagnosis of hearing not only for adults but for newborns also, and this is a great issue today. In addition, a simulated layout for the rapid diagnosis of the average human ear makes it possible to obtain a quantitative criterion hearing assessment for adults. The scientific problem is the lack of quantitative indicator in the diagnosis of middle ear of adults today. A diagnosis of middle ear of newborns is complicated by the presence of the pneumatic system. Thus, the practical significance is to provide newborn hearing screening and providing of the quantitative indicators of the state of the middle ear for adults.Thus, a further step after the layout development for the rapid diagnosis of human middle ear is an experimental study of the layout created. Ref. 10, fig. 2.

Power-Budget Equations and Calibration Factors for Fish Abundance Estimation Using Scientific Echo Sounder and Sonar Systems

Acoustic methods used in fish abundance estimation constitute a key part of the analytic assessment that makes the basis for abundance estimation of marine resources. The methods rely on power-budget equations and calibrated systems. Different formulations of power-budget equations and calibration factors have been proposed for use in scientific echo sounder and sonar systems. There are unresolved questions and apparent inconsistencies in prior literature related to this field. A generic (instrument independent) and unifying theory is presented that attempts to explain the different power-budget and calibration factor formulations proposed and used in prior literature, and how these are mutually related. Deviations and apparent inconsistencies in this literature appear to be explained and corrected. This also includes different (instrument specific) formulations employed in important modern scientific echo sounder systems, and their relationship to the generic theory of abundance estimation. Prior literature is extended to provide more complete power-budget equations for fish abundance estimation and species identification, by accounting for echo integration, electrical termination, and the full range of electrical and acoustical echo sounder parameters. The expressions provide a consistent theoretical basis for improved understanding of conventional methods and instruments used today, also enabling improved sensitivity and error analyses, and correction possibilities.

A numerical study of effects on detection height of a radio acoustic sounding system influenced by atmospheric wind and temperature

Radio acoustic sounding system (RASS) is a detection technique using the interaction between radio wave and acoustic wave to remotely measure vertical profiles of the atmospheric temperature, and usually composed of a Doppler radar with fixed beam (monostatic or bistatic) and an acoustic source with high power. By combining acoustic propagation equation and radio wave propagation equation in a disturbance medium and using a finite-difference time-domain method, a numerical model describing the interaction between acoustic wave and electric wave is constructed, and the model is used to analyze the effects of wind and temperature on detection height of RASS. In the atmospheric temperature background, the propagations of a single frequency acoustic wave packet under different wind conditions are simulated, and the scattering propagation of electric wave packets corresponding to the acoustic scatterer are analyzed and compared. Besides, the entire physical process are described from the angle of energy density. The numerical simulation results show that the propagation trajectories of both acoustic wave and radio wave backscattering echo are changed due to the existence of wind field and temperature profile. The presence of wind field results in an offset of acoustic wave front, reducing the strength and changing the trajectory of radio wave backscattering echo, so that the detection height is limited due to the reduction of receiving data. The simulation results of the acoustic wave reveal that the temperature profile mainly affects the propagation velocity of acoustic wave, while the presence of wind field may result in shifts of propagation trajectory and acoustic wave front, and the greater the wind speed, the more the horizontal shift of acoustic wave front is. The numerical analyses of scattering propagations of radio wave with the acoustic scatterer at the same height under different background atmospheric conditions manifest that the stronger the wind speed, the more the deviation of electric wave echo from the receive antenna is, and the smaller the echo intensity is when the scattering echo propagates to the same position. The theoretical calculations with the acoustic wave scatterer at different heights under the same atmospheric wind field (strong wind) background demonstrate that if the height of scattering point is reduced, the offset of the scattering echo “bunching point” at the same altitude will be greatly improved and the intensity will be enhanced, but it also means the decline of detection height. In order to improve the detection height under the background of wind field, some methods are adopted, such as using a bistatic radar antenna or increasing the reception antenna area.

The influence of roughness, angle, range, and transducer type on the echo signal from planar interfaces.

The received electrical echo signal from a pulse-echo system insonifying a planar interface was measured for varying degrees of rms roughness [0 to 0.29 mm (0 to 1.7 lambda)], angles of incidence, theta, (-7 degrees to 7 degrees), and ranges to a planar or focused transducer. The effect of varying theta is quantified in terms of the energy of the received signal, E(theta), and the normalized spectrum of the received signal. E(theta) is approximately Gaussian when using a planar transducer or a focused transducer with the reflecting interface located at or beyond the focal point. For focused transducers with the interface located closer than the geometrical point of focus, two maxima can sometimes be observed when varying the incident angle. As is generally known, the width of E(theta) is strongly dependent on transducer type, e.g., for a smooth interface, the -3 dB width for a 25.4 mm diameter 5-MHz planar and focused transducer was approximately 0.5 degree and 4 degrees (at the focal point), respectively. E(0 degree) as a function of surface roughness, Rq, was nearly linear on a decibel scale, with a slope of -109 dB/(Rq/lambda) and -61 dB/(Rq/lambda) for planar and focused transducers, respectively. The characteristic nulls present in the normalized spectra of the echo signal at non-normal incidence tend to vanish with increasing Rq when using planar transducers. For focused transducers, the normalized spectra change from relatively flat to monotonically decreasing as Rq increases, and they exhibit reduced amplitude with increased incident angle.

Full duplex speakerphone

A full duplex speakerphone for connection to a telephone system employs adaptive FIR filters for acoustic and electrical echo cancellation in a novel combination with analog gain controls responsive to incoming signal levels and a transmit level control responsive to the receive signal power level. The particular combination minimizes the amount of digital signal processing required to maintain full duplex operation by holding the signal dynamic range within predetermined limits.

Diagnostic ultrasound system

A diagnostic ultrasound system is provided for displaying a color image of a motion of a tissue scans an ultrasonic pulse signal along a tomographic plane to acquire an electrical echo signal, extracts a Doppler signal from the echo signal, calculates velocity data concerning the motion of the tissue for respective sample points on the tomographic plane on the basis of the Doppler signal, and forms data of a B-mode tomographic image on the basis of the echo signal. The system comprises an element for setting a scale along which each of the velocity data over a measurable band of frequencies of the Doppler signal is assigned to each gradation data for color display, the measurable band of frequencies being limited by a pulse repetition frequency of the ultrasonic pulse signal and a given low-velocity band of the measurable frequency band being enhanced in the gradation data than a remaining velocity band of the measurable band, an element for converting the velocity data into the gradation data according to the scale, an element for blanking either one of the converted gradation data and the calculated velocity data at every sample point when each of them exceeds a specified threshold, and an element for displaying the velocity color image subjected to blanking and superimposed on the B-mode tomographic image.

Electric dipole echo in solid solutions

A theory of microwave electric dipole echo in solid solutions is formulated in the example of (KBr)1−x(KCN)x. The behavior of the echo is attributed to tunneling CN− molecules, which are treated as analogs of two-level systems in glasses. A concentration-dependent density of states of the two-level system is used in the calculations. The difference between the behavior of the echo signal in solid solutions and the behavior of the echo in glasses and spin systems is indicated. New echo signals associated with asymmetry of the double-well potential are found.

Loudspeaking telephone using echo cancellers and a voice-switching circuit

A new loudspeaking telephone is proposed that makes duplex communication possible using an adaptive voice-switching circuit and two adaptive echo cancellers. An acoustic echo canceller with a delay capacity of 20 ms cancels the acoustic echo between a loudspeaker and a microphone. An electric echo canceller with a delay capacity of 8 ms cancels the electric echo caused by the impedance mismatch between the line and the balancing network. The characteristics of the acoustic echo path are subject to change by movement of the talker. To cope with such changes, two adaptive filters were installed in an acoustic echo canceller. At the start of talk, the voice-switching circuit inserts a large loss to suppress howling, because the echo cancellers do not replicate the impulse responses of the acoustic and electric echo paths at the beginning of the process stage. When the echo cancellers are replicating the impulse responses with the talker's voice, the inserted loss decreases to 3 dB. Duplex communication can be done in this way. An experimental circuit with three digital signal processors showed that duplex communication becomes possible after repeating voice transmission and reception a couple of times.

Search for electric echoes in K0.3MoO

Search for electric echoes in K0.3MoO

Bidirectional 2 Mbit/s transmission over a single fibre using electrical echo cancellation

Bidirectional transmission over a single fibre using directional couplers and analogue echo cancellation is demonstrated. The implemented echo canceller suppresses crosstalk due to reflections from the local connector and coupler by 11 dB, i.e. it extends the transmission distance by up to 10 km (at 1.3 μm).

Electric dipole echoes in smoky quartz at very low temperatures

Coherent electric echo magnitudes and decay rates have been studied in gamma-irradiated natural quartz crystals in the 5–25 mK range at a frequency of 360 MHz. The echo experiments indicate the presence of two kinds of paraelectric centers. The dynamics of the two-level systems associated with aluminum centers is discussed. The tunneling centers possess rather long phase memory timeT 2 in the millikelvin temperature range (T 2 ∼10−5 sec at 10 mK) andT 2 is inversely proportional to the temperature.T 2 originates from dipolar interactions between the paraelectric centers, and spectral diffusion governs the decay of both the spontaneous and the stimulated echo.

Dephasing of extrinsic tunneling systems in silica glass

The decay of two- and three-pulse electric echoes has been studied in OH-doped Suprasil I fused silica glass. The dephasing time T2 of the OH-associated tunneling systems varies with temperature as T−1.8 between 5 and 100 mK. Evidence for the presence of spectral diffusion is presented.

Intrinsic Electric Dipole Moment of Tunneling Systems in Silica Glasses

Coherent electric echo magnitudes and decay rates have been studied systematically in four silica glasses with differing OH concentrations at a frequency of 0.7 GHz and to temperatures as low as 19 mK. Echoes have been observed in glasses with negligible OH content and originate from intrinsic tunneling systems possessing a mean electric dipole moment of approximately 0.5 D. We show that the OH in fused silica is associated with a distinct extrinsic tunneling species with a larger dipole moment and weaker phonon coupling.

Relaxation times of molecular ions OH? in glasses at very low temperature

This paper presents a detailed study of the temperature dependence of the longitudinal relaxation time T 1 and of the coherence time T 2 of a population of ionic molecular impurities in silica glass. Electric dipolar echoes taken in a temperature range 4–22 mK and a frequency of 370 MHz show that T 1 is governed by a one-phonon process; consequently T 1 varies like T −1; experimental data show that T 2 also varies like T −1 and this in contradiction with predictions which lead to T −2. The relaxation of the spontaneous and stimulated echoes shows that there is a wide distribution of relaxation times (T 1 and T 2) ; from the amplitude of the signal it is also possible to extract both the longitudinal and the transverse electric moment; the coupling constant of the impurities with the strain is found to be as large as 3 eV.

COHERENT ELECTRIC ECHOES IN FUSED SILICA GLASS

Coherent electric echoes are observed at temperatures between 15 and 45 mK in bulk fused silica glasses containing OH impurities. The deduced lifetimes Tj and T' are appreciably longer than those observed for phonon echoes.