Differential Mode Of Operation Research Articles

Differential vibration gyroscope with an axisymmetric resonator and the possibility of self-compensation of its errors

The work considers the differential mode of operation of the vibratory gyroscope and its ability to compensate and auto-compensate the bias and external disturbances by setting a standing wave at certain angles. The possible bias compensation options without mechanical turning of a gyro are presented, including the bias compensation in real-time.

Soft skin-interfaced mechano-acoustic sensors for real-time monitoring and patient feedback on respiratory and swallowing biomechanics

Swallowing is a complex neuromuscular activity regulated by the autonomic nervous system. Millions of adults suffer from dysphagia (impaired or difficulty swallowing), including patients with neurological disorders, head and neck cancer, gastrointestinal diseases, and respiratory disorders. Therapeutic treatments for dysphagia include interventions by speech-language pathologists designed to improve the physiology of the swallowing mechanism by training patients to initiate swallows with sufficient frequency and during the expiratory phase of the breathing cycle. These therapeutic treatments require bulky, expensive equipment to synchronously record swallows and respirations, confined to use in clinical settings. This paper introduces a wireless, wearable technology that enables continuous, mechanoacoustic tracking of respiratory activities and swallows through movements and vibratory processes monitored at the skin surface. Validation studies in healthy adults (n = 67) and patients with dysphagia (n = 4) establish measurement equivalency to existing clinical standard equipment. Additional studies using a differential mode of operation reveal similar performance even during routine daily activities and vigorous exercise. A graphical user interface with real-time data analytics and a separate, optional wireless module support both visual and haptic forms of feedback to facilitate the treatment of patients with dysphagia.

Self-Compensation for Disturbances in Differential Vibratory Gyroscope for Space Navigation

In order to meet in many aspects contradictory requirements to gyroscopes used in space applications, this paper proposes to use the multimode Coriolis vibratory gyroscope, which operates in a new differential mode in addition to well-known rate and rate-integrating modes. The differential mode of operation can provide high resistance to external disturbances acting on the gyroscope under operating in launch, docking, and landing regimes of spacecraft. The differential mode of operation differs from the other two known modes by the presence of two, X and Y, measurement channels. Each of the channel measures angle rate with opposite sign. This mode of operation can be implemented by the disposition of standing wave pattern between the drive and sense electrodes. The paper presents promising capabilities of the differential mode of operation to self-compensate for external disturbances. The condition for the standing wave angle disposition that provides maximum compensation for the disturbances is proposed. Numerical and graphical test results on the determination of shock suppression coefficient, vibration sensitivity reduction coefficient, and also reduction of sensitivity to constant and variable magnetic fields are presented.

Triple-mode vibratory gyroscope

Coriolis vibratory gyroscope (CVG) is one of the chronologically latest gyroscopic technologies that appeared on the world market in the 90s of the last century. This technology has spread throughout the world for a relatively short time, mainly due to its micro-miniature version based on the micro-electro-mechanical system (MEMS), the so-called MEMS gyroscopes. There are two well-known modes of Coriolis vibratory gyro operation. These are rate mode and rate-integrating modes described in many works of different authors. There is also known dual mode CVG in which two abovementioned modes of operation have been combined in one gyro with automatic switching from one mode to another. Such a dual-mode CVG gains additional advantages over competing technologies, such as laser and fiber-optic gyroscopes. Recently, differential mode of operation for single mass CVG has been developed in Ukraine. It was shown that differential mode of operation has excellent external disturbances rejection properties.This paper considers each mode of CVG operation and the questions of how to embed the differential mode into two first abovementioned ones to obtain triple-mode CVG which will widen application area and tighten position over competitive technologies. This triple-mode CVG can surely be realized in MEMS and non-MEMS gyros.Thus, the following is defined, Differential CVG can be considered as third mode of operation for vibratory gyroscopes along with two well-known rate and rate-integrating ones. Differential mode of operation can be built-in the single gyro together with the two others, rate and rate-integrating modes, to implement triple-mode CVG. Triple-mode gyro can be implemented both for MEMS and non MEMS vibratory gyros.Differential mode of operation has greater, than rate mode, external disturbances rejection factor and can be used when motion occurs in harsh environment.Realization of triple mode CVG gives it highest «versatility» in comparison with competitive gyro technologies like ring laser gyro and fiber optic one.

Quench Detection for High-Temperature Superconductor Conductors Using Acoustic Thermometry

Detecting local heat-dissipating zones in high-temperature superconductor (HTS) magnets is a challenging task due to slow propagation of such zones in HTS conductors. For long conductor lengths, voltage-based methods may not provide a sufficient sensitivity or redundancy, and therefore nonvoltage-based detection alternatives are being sought. One of those is the recently proposed method of Eigen Frequency Thermometry (EFT), which is an active acoustic technique for a fast and nonintrusive detection of “hot spots,” utilizing temperature dependence of the conductor elastic moduli. In this work, we demonstrate the efficiency of EFT for detecting localized heating in a 1.2-m-long sample of REBCO tape immersed in liquid nitrogen, and benchmark sensitivity of the acoustic detection with respect to voltage, hot spot temperature, and power dissipation in the conductor. Modifying the original technique for differential mode of operation enables a much improved sensitivity, and adds a hot spot localization capability. Furthermore, we adapt this technique to subscale coils wound with REBCO CORC conductor built in the framework of U.S. Magnet Development Program. A successful thermal-based detection of dissipation onset at the critical current for a two-layer canted CORC dipole assembly is discussed.

Effective rejection of acoustic and magnetic fields’ disturbances by single-mass differential vibratory gyroscope

Differential mode of operation as a third mode unlike the first one - rate and second one - rate-integrating modes of vibratory gyroscopes is analyzed in this paper. In the differential mode of operation the standing wave is keeping in between the electrodes. In this case two X and Y measurement channels are created with opposite signs of angle rates. Biases and scale factors of X and Y measurement channels are dependant on standing wave angular position θ relative to drive, X, electrode. There is angular position θ * at which X measurement channel scale factor SFx is equal to Y measurement channel scale factor SFy. Rejection factors of external acoustic impulses which frequency is close to resonant one, and also of constant and variable magnetic fields are experimentally determined in this paper when standing wave angle is located at the θ * angular position. As opposed to other types of differential gyros that can be implemented using two or multi-mass resonator designs, single-mass resonator gyros can have higher rejection factors for different disturbances at the θ * angular position of standing wave providing meeting the requirements of many important applications. Test results show excellent disturbance rejection properties of differential mode of operation for single-mass resonator gyros. Comparison of responses of the differential mode with the rate mode of the same gyro on disturbances is also carried out in this work.

Well-established materials in microelectronic devices systems for differential-mode extended-gate field effect transistor chemical sensors

Well-established materials commonly used in microfabrication industry were studied as chemical sensing elements of extended gate field effect transistor (EGFET) chemical sensors. Microelectronic components were used in the differential mode of operation. Three differential pairs of films made of polyaniline (protonated and non-protonated), fluorine doped tin oxide and titanium dioxide were used: PANI-EB×PANI-ES, PANI-EB×FTO and FTO×TiO2. Good linearity was observed for all cases in the pH range 3 to 8. The differential measurements were also performed as a function of: i) temperature in the range 30°C to 50°C, ii) buffer concentration from 1mM to 400mM, and iii) time, for three hours. Hysteresis measurements for the 5-2-5-8-5pH loop cycle were also conducted. The pair composed of polyaniline in the protonated and non-protonated form presented the best results with a sensitivity of 37±4mV/pH, good linearity, and stable response against variation of temperature and buffer concentration. A similarity in ion-sensing mechanisms and electrical properties of the single films is necessary for the fabrication of good and stable differential sensors as will be discussed. These materials can be satisfactorily used in miniaturized electronic sensor systems, thus promising great advances in the field.

The Effect of Humidity on the Stability of LTCC Pressure Sensors

The Effect of Humidity on the Stability of LTCC Pressure SensorsLTCC-based pressure sensors are promising candidates for wet-wet applications in which the effect of the surrounding media on the sensor's characteristics is of key importance. The effect of humidity on the sensor's stability can be a problem, particularly in the case of capacitive sensors. A differential mode of operation can be a good solution, but manufacturing the appropriate sensing capacitors remains a major challenge. In the case of piezoresistive sensors the influence of humidity is less critical, but it still should be considered as an important parameter when designing sensors for low-pressure ranges. In this paper we discuss the stability of the sensors' offset characteristics, which was inspected closely using experimental and numerical analyses.

A ROOM TEMPERATURE BALLISTIC DEFLECTION TRANSISTOR FOR HIGH PERFORMANCE APPLICATIONS

The Ballistic Deflection Transistor (BDT) is a novel device that is based upon an electron steering and a ballistic deflection effect. Composed of an InGaAs - InAlAs heterostructure on an InP substrate, this material system provides a large mean free path and high mobility to support ballistic transport at room temperature. The planar nature of the device enables a two step lithography process, as well, implies a very low capacitance design. This transistor is unique in that no doping junction or barrier structure is employed. Rather, the transistor utilizes a two-dimensional electron gas (2DEG) to achieve ballistic electron transport in a gated microstructure, combined with asymmetric geometrical deflection. Motivated by reduced transit times, the structure can be operated such that current never stops flowing, but rather is only directed toward one of two output drain terminals. The BDT is unique in that it possesses both a positive and negative transconductance region. Experimental measurements have indicated that the transconductance of the device increases with applied drain-source voltage. DC measurements of prototype devices have verified small signal voltage gains of over 150, with transconductance values from 45 to 130 mS/mm depending upon geometry and bias. Gate-channel separation is currently 80nm, and allows for higher transconductance through scaling. The six terminal device enables a normally differential mode of operation, and provides two drain outputs. These outputs, depending on gate bias, are either complementary or non-complementary. This facilitates a wide variety of circuit design techniques. Given the ultralow capacitive design, initial estimates of ft, for the device fabricated with a 430nm gate width, are over a THz.

Joint estimation of systematic ephemeride errors and results of direct measurements in a differential mode of operation by a satellite radio navigation system

A method that makes it possible to increase the precision with which the coordinates of a user in a differential mode of operation of a satellite radio navigation system are determined, is considered. The increased precision is achieved through separate introduction of corrections to the predicted coordinates of the satellite and the results of navigation measurements.

Results of Differential Mode of Operation of the Standard Time and Frequency Signal (STFS) Broadcast via INSAT

We describe the operation of the Standard Time & Frequency Signal (STFS) broadcast via INSAT satellite in the so-called online differential mode. The transmission setup at the Delhi Earth station and the recent version of the STFS decoder are briefly described. Regular data recording carried out at NPL, New Delhi, NRL, Trombay, field station at Mt Abu and ERTL(E), Calcutta have been used in this paper to draw conclusions regarding improvement in time transfer accuracy.

Excess enthalpy measurements using a novel highly refined microflow calorimeter and the prediction of vapour-liquid equilibria from such data

A novel differential microflow calorimeter has been developed for excess enthalpy measurement on endothermic liquid systems. The design incorporates precise temperature equilibration of the fluids before mixing, the elimination of flow-rate- and physical-property-dependent heat leaks and a differential mode of operation based on a careful analysis of entropy generation in flows with mixing and friction. The compensation for frictional heating and the lack of dependence of measurements on flow rate and mixture physical properties other than h E represents a major advance. Measurements for the well-tested hexane-cyclohexane system (adopted as a reference standard by IUPAC) had an average deviation of only 0.21 J gmol −1, surpassing in accuracy any previous measurements on a flow calorimeter. Heat-of-mixing data are presented for the n-hexane-toluene system at 25, 40 and 55°C. Isobaric and isothermal vapour-liquid equilibrium data are predicted from the measured h E data using a new modification of the UNIQUAC equation aimed at improving the latter's temperature dependence. The predicted VLE data are in very good agreement with those measured by Sieg, Saito and by Michishita et al.

A differential photodetector, employing photoconductivity, for subnanosecond laser beam position measurements

A novel device is described which provides the possibility for accurate sensing of laser beam or interference fringe positions, utilising a pair of photoconductive elements that differentiates the light intensity with respect to the lateral coordinate. The device consists of a microstripline T structure with an InP:Fe chip incorporated in the middle. The chip has a metallic layer divided into three parts by two narrow photoconductive gaps, separated by a distance of 350 mu m. The central part is connected to a microstripline that constitutes the output branch, while the two side parts are connected to two similar microstriplines that are biased with DC voltages of equal magnitudes but opposite polarities. The differential mode of operation gives improved resolution as compared with ordinary photodetectors. In the case of gaussian beam position measurements a lateral resolution of 10 mu m could be demonstrated experimentally, and in measurements of interference fringe positions the resolution 2 pi /60 rad was achieved. In both cases these limits were set by the mechanical translation stage used. The temporal resolution was set by the carrier lifetime of the material, 200 ps.

Microflow calorimeter design for heats of mixing

AbstractMicroflow calorimeter design for heats of mixing is surveyed. Precise temperature equilibration of the fluids before mixing, the elimination of frictional energy effects from the instrument response, and the absence of flow‐rate and physical‐property‐dependent heat leaks are particularly important. A design using a differential mode of operation is based on a careful analysis of entropy generation in flows with mixing and friction. The compensation for frictional heating and the lack of dependence of measurements on flow rate and mixture physical properties other than hE represents a major advance. Measured data for the welltested cyclohexane‐hexane system had an average deviation of only 0.41%. For the more viscous cyclohexane‐1‐hexanol system, measured data of similar precision are considered the best available.

Unexploited Potentials of Loran-C

Current Loran-C radio navigation equipment has demonstrated a repeatable precision index of less than 0.01 μs/km. Thus, two co-located receivers measuring the same time difference will deviate less than this amount as to the standard deviation of their measured time difference. It is therefore concluded that operation of Loran-C in a differential mode is a feasible technique for such practical matters as collision avoidance, instrument landing systems, air traffic control, precise location of surface vessels used out of sight of land in underwater exploration, and ground based vehicle location in the non-urban environment. By differential operation mode, we mean that two vehicles can determine their distance apart, their rate of closing or separation, and indeed their direction of relative motion, if the measured time difference information on each vehicle is relayed between vehicles. Loran-C can be compared quantitatively with other systems such as Omega operating in a differential mode. A comparison of Loran-C data with the Beukers-Nard Omega data reveals a possible 20 to 100 accuracy improvement factor if we use Loran-C instead of Omega in the 0 to 700 km differential separation range. We conclude that the fundamental reason for part of the improvement is the reciprocal phase measurement improvement with frequency. The remainder of the improvement is a consequence of the greater stability of the pulsed ground wave propagation mechanism of Loran-C as compared with the single frequency ionospheric waves of Omega. Frequencies greater than 100 kHz would give greater improvement with a loss of range or coverage area. We have found that Loran-C is an excellent propagation measuring device for the detection and identification of effects of irregular, in-homogeneous terrain in the spatial domain, and the study of meteorological variations in the time domain. Furthermore, the Loran-C skywave signal can be used as a D-region diagnostic to study particle precipitation events and D-region variations with latitude, season and solar zenith angle. We make the observation from our Loran-C studies that the first prerequisite to a capability for prediction of propagation phenomena is the ability to separate, identify, and understand the physical nature of the observed radio measurements. This prediction capability is essential to the successful operation of radio navigation systems in both the normal and the differential mode of operation.

Differential mode of operation for bucket-brigade circuits

A differential circuit configuration is described that suppresses unwanted clock-frequency spectral energy at the output of a charge-transfer device. The differential mode of operation also eliminates the d.c. offset voltage that is characteristic of these devices. Experimental results are presented.

LORAN-C on the Lower Great Lakes

In 1970–71 a study of Loran-C reception and stability characteristics was carried out along the Lower Great Lakes. By setting up calibration stations for periods from 1 hour to 18 days between Eastern Lake Ontario and Western Lake Erie, measures were obtained of chain variability, instrument variability, signal strength and certain other effects. Calibration curves were obtained which permit correction of Loran data over Lake Ontario and Lake Erie. Monitor stations were used to determine the advantage resulting from use of the differential mode of operation. Results indicated that any propagation variability was small as compared to instrumental and chain variability. In the differential mode, overall system accuracies, geometry and signal strength appear to be attractive for precise navigation or for a large area survey operation in the Lower Lakes. The study was sponsored by the Canadian Hydrographic Service.