Duty Cycle Measurement Research Articles

A Real-Time Determination Method for Homodyne Grating Interferometer Signal Nonlinear Error Based on Duty Cycle Measurement of States

A Real-Time Determination Method for Homodyne Grating Interferometer Signal Nonlinear Error Based on Duty Cycle Measurement of States

The association of arterial blood pressure waveform-derived area duty cycle with intra-arrest hemodynamics and cardiac arrest outcomes

AimDevelop a novel, physiology-based measurement of duty cycle (Arterial Blood Pressure–Area Duty Cycle [ABP–ADC]) and evaluate the association of ABP–ADC with intra-arrest hemodynamics and patient outcomes. MethodsThis was a secondary retrospective study of prospectively collected data from the ICU-RESUS trial (NCT02837497). Invasive arterial waveform data were used to derive ABP–ADC. The primary exposure was ABP–ADC group (<30%; 30–35%; >35%). The primary outcome was systolic blood pressure (sBP). Secondary outcomes included intra-arrest physiologic goals, CPR quality targets, and patient outcomes. In an exploratory analysis, adjusted splines and receiver operating characteristic (ROC) curves were used to determine an optimal ABP–ADC associated with improved hemodynamics and outcomes using a multivariable model. ResultsOf 1129 CPR events, 273 had evaluable arterial waveform data. Mean age is 2.9 years + 4.9 months. Mean ABP–ADC was 32.5% + 5.0%. In univariable analysis, higher ABP–ADC was associated with lower sBP (p < 0.01) and failing to achieve sBP targets (p < 0.01). Other intra-arrest physiologic parameters, quality metrics, and patient outcomes were similar across ABP–ADC groups. Using spline/ROC analysis and clinical judgement, the optimal ABP–ADC cut point was set at 33%. On multivariable analysis, sBP was significantly higher (point estimate 13.18 mmHg, CI95 5.30–21.07, p < 0.01) among patients with ABP–ADC < 33%. Other intra-arrest physiologic and patient outcomes were similar. ConclusionsIn this multicenter cohort, a lower ABP–ADC was associated with higher sBPs during CPR. Although ABP–ADC was not associated with outcomes, further studies are needed to define the interactions between CPR mechanics and intra arrest patient physiology.

An Equal Precision Programmed Cymometer Design Using Low-Power Technique

Based on equal precision frequency measurement and pulse counting technique, a multi-period synchronous frequency measurement method is proposed in this paper. A programmed cymometer is designed with a full frequency band with equal precision measurement and improved measurement accuracy. In addition to adopting a low-power gate-control clock technique, the strong stability of our design is also carried out through the filtering of interference signals. Finally, the designed circuit is implemented with FPGA. The experimental results show that the static power consumption of the programmable frequency meter testing platform designed after continuous operation for 100 h is only 0.56 W, and the input impedance is 1 M Ω/40 pF. At the same time, the errors of frequency, cycle measurement, duty cycle measurement, and time interval are within a reasonable range. In addition, the measurement accuracy requirements for various indicators can also be met at a maximum frequency of 100 MHz. Therefore, this work can provide a feasible design method for low-power consumption electrical systems that are easy to replicate.

Design of SOPC digital frequency meter based on MicroBlaze

A method of SOPC implementation of digital frequency meter is presented in this paper. In the method, Encapsulated AXI IP core for frequency measurement and duty cycle measurement are configured with the embedded soft core MicroBlaze processor. The parameter measurement of the digital frequency meter is implemented by FPGA logic resources, and the measured data are transmitted to the soft core processor via AXI bus. The computation, control and display is completed by Microblaze soft core. The system is verified and tested on the Basys3 board card launched by digilent company. The results show that the system has the advantages of accurate measurement, good stability, simple scheme and low cost.

Improved Spacecraft Magnetic Attitude Maneuvering

A magnetometer is essential in spacecraft magnetic attitude control due to the need for magnetic field information to compute the control command. The measurements of the magnetometer, however, are usually affected by other electric currents in the spacecraft, especially those of the magnetic coils when they are turned on during actuation. As a result, magnetic rods and magnetometers are usually turned on at alternate times, resulting in a reduced duty cycle of the magnetic rods, and hence longer maneuver times. This paper presents a magnetic attitude control system with extended duty cycle and low magnetometer measurements frequency. Instead of measurements, a computed magnetic field strength vector is used for updating the control command during the duty cycle. Using the measured spacecraft rotational motion, and knowing the control torque command, it is possible to compute the magnetic field strength vector. These computations are corrected using magnetometer measurements at a lower rate. The Tikhonov regularization approach is implemented to solve the singular magnetic torque system. This algorithm is demonstrated via Monte Carlo numerical simulations to have faster attitude maneuvers and lower power consumption by the magnetic rods. Real data obtained from the Cascade Smallsat and Ionospheric Polar Explorer spacecraft are used for validation of the proposed approach.

Comparison of Chest Compressions Metrics Measured Using the Laerdal Skill Reporter and Q-CPR: A Simulation Study.

There has been an increased emphasis on the quality of chest compressions as a part of the cardiopulmonary resuscitation (CPR) bundle of care for recent times. During CPR training, chest compression quality parameters can be measured directly from sensors within a manikin or from external devices placed on the manikin chest that use accelerometer-based technology. The aim of this study was to compare external chest compression data from the manikin-based Laerdal Skill Reporter (LSR) and the accelerometer-based Q-CPR technology, incorporated into the Philips MRx defibrillator, during CPR on a single Resusci Anne Simulator manikin. Each paramedic (n = 15) performed 2 sessions of 2 minutes of chest compressions, with a 2-minute rest period in between sessions. Both over-the-head and from-the-side positions were used on a single manikin. The quality of chest compressions were concurrently measured using both LSR and Philips MRx Q-CPR accelerometer with audiovisual feedback disabled. There was no significant difference in the measurement of the number of chest compressions performed in 2 minutes, the compression rate, total number of compressions of adequate depth, or the number of compressions exhibiting leaning between the LSR and the Phillips Q-CPR devices. There was a significant difference in measurement of compression depth (P < 0.0001) and duty cycle (P < 0.0001) with the MRx Q-CPR accelerometer demonstrating both lower compression depth and duty cycle compared with LSR. There was no significant difference in most chest compression quality metrics measured between the LSR and the Phillips Q-CPR devices when measured on a manikin. However, there were significant differences in the measurement of duty cycle and also the depth of compressions between the 2 devices with the Phillips Q-CPR device measuring lower depth of compression and duty cycle compared with the LSR device.

Top‐down protein identification of proteasome proteins with nanoLC‐FT‐ICR‐MS employing data‐independent fragmentation methods

A comparison of different data-independent fragmentation methods combined with LC coupled to high-resolution FT-ICR-MS/MS is presented for top-down MS of protein mixtures. Proteins composing the 20S and 19S proteasome complexes and their PTMs were identified using a 15 T FT-ICR mass spectrometer. The data-independent fragmentation modes with LC timescales allowed for higher duty-cycle measurements that better suit online LC-FT-ICR-MS. Protein top-down dissociation was effected by funnel-skimmer collisionally activated dissociation (FS-CAD) and CASI (continuous accumulation of selected ions)-CAD. The N-termini for 9 of the 14 20S proteasome proteins were found to be modified, and the α3 protein was found to be phosphorylated; these results are consistent with previous reports. Mass-measurement accuracy with the LC-FT-ICR system for the 20- to 30-kDa 20S proteasome proteins was 1 ppm. The intact mass of the 100-kDa Rpn1 subunit from the 19S proteasome complex regulatory particle was measured with a deviation of 17 ppm. The CASI-CAD technique is a complementary tool for intact-protein fragmentation and is an effective addition to the growing inventory of dissociation methods that are compatible with online protein separation coupled to FT-ICR-MS.

Quantification of Improvements in Static and Dynamic Ventilatory Measures Following Lung Volume Reduction Surgery for Severe COPD

Rationale: This study quantitatively measured the effects of lung volume reduction surgery (LVRS) on spirometry, static and dynamic lung and chest wall volume subdivision mechanics, and cardiopulmonary exercise measures. Methods: Patients with severe COPD (mean FEV1 = 23 ± 6% predicted) undergoing LVRS evaluation were recruited. Spirometry, plethysmography and exercise capacity were obtained within 6 months pre-LVRS and again within 12 months post- LVRS. Ventilatory mechanics were quantified using stationary optoelectronic plethysmography (OEP) during spontaneous tidal breathing and during maximum voluntary ventilation (MVV). Statistical significance was set at P< 0.05. Results:Ten consecutive patients met criteria for LVRS (5 females, 5 males, age: 62±6yrs). Post -LVRS (mean follow up 7 months ± 2 months), the group showed significant improvements in dyspnea scores (pre 4±1 versus post 2 ± 2), peak exercise workload (pre 37± 21 watts versus post 50 ± 27watts ), heart rate (pre 109±19 beats per minutes [bpm] versus post 118±19 bpm), duty cycle (pre 30.8 ± 3.8% versus post 38.0 ± 5.7%), and spirometric measurements (forced expiratory volume in 1 second [FEV1] pre 23 ± 6% versus post 32 ± 13%, total lung capacity / residual lung volume pre 50 ± 8 versus 50 ± 11) . Six to 12 month changes in OEP measurements were observed in an increased percent contribution of the abdomen compartment during tidal breathing (41.2±6.2% versus 44.3±8.9%, P=0.03) and in percent contribution of the pulmonary ribcage compartment during MVV (34.5±10.3 versus 44.9±11.1%, P=0.02). Significant improvements in dynamic hyperinflation during MVV occurred, demonstrated by decreases rather than increases in end expiratory volume (EEV) in the pulmonary ribcage (pre 207.0 ± 288.2 ml versus post -85.0 ± 255.9 ml) and abdominal ribcage compartments (pre 229.1 ± 182.4 ml versus post -17.0 ± 136.2 ml) during the maneuver. Conclusions: Post-LVRS, patients with severe COPD demonstrate significant favorable changes in ventilatory mechanics, during tidal and maximal voluntary breathing. Future work is necessary to determine if these findings are clinically relevant, and extend to other environments such as exercise.

On the Measurement of Duty Cycle and Channel Occupancy Rate

Duty cycle (DC) and channel occupancy rate (COR) measurements are important to characterize the availability of white space for cognitive radio systems (CRSs). The COR is related to the real occupancy of channels considered by a CRS but despite its importance it has not yet been widely considered for spectrum use measurements. Spectrum use measurements have typically used detection with a single threshold. In order to improve sensitivity, we utilize the localization algorithm based on double-thresholding (LAD) with the adjacent cluster combining (ACC) to spectrum use measurements and propose a modified version of it. We theoretically analyze the probability of false alarm after the LAD processing in a realistic case with correlation among samples and theoretically analyze the probability of detection after the LAD ACC processing. We propose COR estimation algorithm based on hard decision fusion of the frequency domain decisions. Measurement and theoretical results confirm the accurate DC and COR estimation and the significant sensitivity gains with the proposed algorithms.

Time-resolved measurement of pulse-to-pulse heating effects in a terahertz quantum cascade laser using an NbN superconducting detector

Joule heating causes significant degradation in the power emitted from terahertz-frequency quantum-cascade lasers (THz QCLs). However, to date, it has not been possible to characterize the thermal equilibration time of these devices, since THz power degradation over sub-millisecond time-scales cannot be resolved using conventional bolometric or pyroelectric detectors. In this letter, we use a superconducting antenna-coupled niobium nitride detector to measure the emission from a THz QCL with a nanosecond-scale time-resolution. The emitted THz power is shown to decay more rapidly at higher heat-sink temperatures, and in steady-state the power reduces as the repetition rate of the driving pulses increases. The pulse-to-pulse variation in active-region temperature is inferred by comparing the THz signals with those obtained from low duty-cycle measurements. A thermal resistance of 8.2 ± 0.6 K/W is determined, which is in good agreement with earlier measurements, and we calculate a 370 ± 90-μs bulk heat-storage time, which corresponds to the simulated heat capacity of the device substrate.

Writer Field Gradient Measurement on Spinstand

The gradient of magnetic head field is very critical in the writing process and it is one of the key factors to determine the achievable linear density of magnetic recording system. This work proposed a new method to measure the writer field gradient on Spinstand. The even harmonic ripple effect [4] is used to produce the modulated magnetostatic field at the writing transitions generated from the old data pattern at leading edge side of the writer. The newly written single tone signals have the modulated transition shift. Through the duty cycle measurement of the single tone signals, the delta transition shift can be measured. With the calculated magnetostatic field based on the media magnetic properties and the measured size of writer footprint, the writer field gradient equals the ratio of delta magnetostatic field over delta transition shift.

SU-E-T-172: Portal Dosimetry of Gated VMAT; with and Without Gating

Purpose: To study duty cycle and respiratory period influence on VMAT delivery using portal dosimetry. Methods: For this study, we selected 12 ARC fields from four different gated VMAT plans with Varian, TrueBeam 6 MV photon beam and HD120 MLC. For Planning and portal dose prediction we used Varian, Eclipse (Version 10.0) AAA and PDIP algorithms respectively. We acquired integrated portal images with and without gated arc fields delivered to EPID at SID 140cm. We simulated respiratory periods with Quasar, Motion Phantom. For gated delivery, we used planned duty cycle for patient respiratory trace, and 6 sec per breath (SPB) and duty cycles 40%, 30%, 20% and 10% with 3SPB. Eclipse, Portal dosimetry software was used for Gamma analyses of measured and predicted portal dose images. In addition, we compared with and without gated portal dose images of same arc. MLC log file analyses of delivered arcs were done with Mobius, Dose lab software. Gamma passing criteria is to have gamma<1 for greater than 90% data points. Results: For all arcs, predicted vs. measured dose distributions passed with criteria ΔD = 3% & DTA = 3mm, excluding few 10% duty cycle measurements. For these, pass criteria is ΔD = 5% & DTA = 4mm. Similarly, with and without gated portal dose image comparison passed the criteria of ΔD = 1% & DTA = 1mm excluding few 10% duty cycle measurements. For these pass criteria is ΔD = 2% & DTA = 2mm. For all delivered arcs, Leaf error 95 percentile is < 0. 1mm and error RMS is below 0.05mmConclusion: Except 10 % duty cycle, the gating influence on VMAT delivery is minimal. Therefore, gated VMAT QA can be done without gating. Duty cycles larger than 20% are recommended to minimize delivery errors.

Power management of autonomous wireless sensor node for structure health monitoring

This paper presents the design concepts of wireless sensor network system constructed with autonomous sensing nodes, which operates at extremely low power levels. At first, conventional, wired civil structure health-monitoring system is reviewed. Then, the monitoring methodology is discussed focusing quantitative measurement accuracy. Issues of node synchronized sampling, multi-layer cluster, node distance and integrated sensor node module are discussed. Also, radio transceiver protocol candidates are reviewed from the point of connection to the Internet gateway. Sensor node consists of microprocessor, sensing analog front end, and radio transceiver. Last two factors are critical for power consumption. Therefore, low duty cycle measurement is essential, in order to accomplish the ultra low power level, which is equivalent to energy harvesting source, such as piezoelectric and solar cells, sensor node power management device circuit design is demonstrated for the high-spec measurement.

High resolution demodulation technique for Sagnac fibre optics gyroscopes using a low frequency quasi-synchronous clock

Abstract A simple technique which employs a low frequency quasi-synchronous clock was developed to measure duty-cycles with high resolution. For the same measurement resolution, the proposed circuit can operate with clock frequencies typically 1000 times lower than in conventional digital duty-cycle measurement system with synchronous clock. The proposed circuit is composed of only two Digital Direct Synthesis integrated circuits and one Complex Programmable Logic Device. Experimental results obtained with a prototype of the proposed time measurement system show that, for an emulated zero-cross fibre optics gyroscope output signal with 100 kHz and Δ T = 100 ns (duty-cycle of 50.25%), a resolution of 100 ps can be achieved using a 10.01 MHz frequency clock.

Duty Cycle Measurement Techniques for Adaptive and Resilient Autonomic Systems

When systems are deployed in environments where change is the rule rather than the exception, adaptability and resilience play a crucial role in order to preserve good quality of service. This work analyses methods that can be adopted for the duty cycle measurement of sensor-originated waveforms. These methods start from the assumption that no regular sampling is possible and thus they are naturally thought for an adaptive coexistence with other heterogeneous and variable tasks. Hence, the waveform carrying the information from low-priority sensors can be sampled only at instants that are non-controlled. To tackle this problem, this paper proposes some algorithms for the duty cycle measurement of a digital pulse train signal that is sampled at random instants. The solutions are easy to implement and lightweight so that they can be scheduled in extremely loaded microcontrollers. The results show a fast convergence to the duty cycle value; in particular, a considerable gain with respect to other known solutions is obtained in terms of the average number of samples necessary to evaluate the duty cycle with a desired accuracy is obtained.

High-Resolution Magnetometry with a Spinor Bose-Einstein Condensate

We demonstrate a precise magnetic microscope based on direct imaging of the Larmor precession of a 87Rb spinor Bose-Einstein condensate. This magnetometer attains a field sensitivity of 8.3 pT/Hz1/2 over a measurement area of 120 microm2, an improvement over the low-frequency field sensitivity of modern SQUID magnetometers. The achieved phase sensitivity is close to the atom shot-noise limit, estimated as 0.15 pT/Hz1/2 for a unity duty cycle measurement, suggesting the possibilities of spatially resolved spin-squeezed magnetometry. This magnetometer marks a significant application of degenerate atomic gases to metrology.

Optical measurement of depth and duty cycle for binary diffraction gratings with subwavelength features.

We describe a new and unique method for simultaneous determination of the groove depth and duty cycle of binary diffraction gratings. For a near-normal angle of incidence, the +1 and -1 diffracted orders will behave nearly the same as the duty cycle is varied for a fixed grating depth. The difference in their behavior, quantified as the ratio of their respective diffraction efficiencies, is compared to a look-up table generated by rigorous coupled-wave theory, and the duty cycle of the grating is thus obtained as a function of grating depth. Performing the same analysis for the orthogonal probe-light polarization results in a different functional dependence of the duty cycle on the grating depth. By use of both TE and TM polarizations, the depth and duty cycle for the grating are obtained by the intersection of the functions generated by the individual polarizations. These measurements can also be used to assess qualitatively both the uniformity of the grating and the symmetry of the grating profile. Comparison with scanning electron microscope images shows excellent agreement. This method is advantageous since it can be carried out rapidly, is accurate and repeatable, does not damage the sample, and uses low-cost, commonly available equipment. Since this method consists of only four fixed simple measurements, it is highly suitable for quality control in a manufacturing environment.

A robust and accurate algorithm for time measurements of periodic signals based on correlation techniques

Algorithms incorporated in the oscilloscopes allow automatic measurement of periodic waveforms. These algorithms are often based on IEC Standards. They are not only useful for built-in oscilloscope measurements, but also as stand-alone algorithms implemented, for example, on a computer. The conventional algorithms used for time measurement of periodic signals (e.g., period, positive and negative duty cycles and pulse widths) are based on crossings of a reference level. The crossings method for time measurement fails when there are spurious crossings around the reference level. We have developed a robust and accurate algorithm for time measurement of period, duty cycle, and pulse width, based on correlation techniques. The algorithm for determining the period is generic to any periodic waveform with at least one period. The algorithm for duty cycles and pulse widths is only valid for pulse-shaped waveforms. Using example waveforms, our algorithm is shown to produce more robust and accurate time measurements than the built-in algorithm used in a commercial oscilloscope. With modern-day computing power, our algorithm takes between 10 and 20 ms to perform measurements for a waveform of 1000 8-bit data-points on a Pentium III laptop.

A microaccelerometer structure fabricated in silicon-on-insulator using a focused ion beam process

Focused ion beam processing (FIB) has been employed for the fabrication of a microaccelerometer structure starting with bonded silicon-on-insulator substrates. A short FIB processing step involves cutting a narrow gap obliquely in a silicon beam. This gap is used for reading out an acceleration. The process time is less than 2 min which could be viable for the manufacture of high value sensors. SOI material is ideal to fabricate suspended structures with simple processing steps. A novel, so-called `tapping mode' readout is studied. It is based on a periodic closing of the readout gap and a duty cycle measurement. Electron tunnelling readout is proposed for high sensitivity applications.