Pulsed Measurements Research Articles

Interpass temperature effects on WAAM ER316L stainless steel corrosion using potentiostatic pulse tests

The effect of interpass temperature on the microstructure and pit nucleation behaviour in wire and arc additive manufacturing (WAAM) deposited ER316L stainless steel is investigated. Lowering the interpass temperature increases the ferrite content and decreases the sigma phase precipitation. Potentiostatic pulse measurements show that the WAAM ER316L pits develop predominantly near sigma phases and have higher pit density compared to a wrought 316L (UNS S31600). The pitting susceptibility of WAAM ER316L increases with increasing interpass temperature due to the precipitation of larger sigma phase enhancing the elemental segregation.

Virtual reality exposure aided-diagnosis system for anxiety disorders: Long short-term memory architecture for three levels of anxiety recognition.

The COVID-19 pandemic has resulted in increased psychological pressure on mental health since 2019. The resulting anxiety and stress have permeated every aspect of life during confinement. To provide psychologists with an unbiased measure that can aid in the preliminary diagnosis of anxiety disorders and be used as an initial treatment in cognitive-behavioral therapy, this article introduces automated recognition of three levels of anxiety. Anxiety was elicited by exposing participants to virtual environments inspired by social situations in reference to the Liebowitz social anxiety scale. Relevant parameters, such as heart rate variability and vasoconstriction were derived from the measurement of the blood volume pulse (BVP) signal. A long short-term memory architecture achieved an accuracy of approximately 98% on the training and test set. The generated model allowed for careful study of the state of seven phobic participants during virtual reality exposure (VRE).

An improved hybrid photon detector based on a SiC Schottky diode

In order to improve the temporal response of SiC-HPMTs, a new SiC detector with a faster time response (leading edge 1.5 ns, FWHM 4 ns) was developed for constructing an improved SiC-HPMT. Then the properties of the improved SiC-HPMT were studied in detail. Compared with those of the previous SiC-HPMT, the temporal response of the improved SiC-HPMT, with a leading edge of about 2 ns and a FWHM of less than 5ns was effectively improved. The maximum linear current that exceeded 630 mA depends on both the accelerating and focusing voltage (Va) and the bias voltage (VSiC) of the SiC detector, but has a strong dependence on Va. The scintillation detector comprised of the improved SiC-HPMT and an EJ228 scintillator can accurately obtain the multiple peaks characteristic of the pulsed X-ray source, which indicates that the improved SiC-HPMT can well satisfy the requirements for measuring the time information of fast pulsed radiation fields. In addition, the SiC-HPMT should be placed at the position that deviates from the radiation beam to avoid the direct irradiation on the SiC detector. The improved SiC-HPMT will further expand its application in pulsed radiation field measurements and become a supplement for existing photoelectric detectors.

Full polarization reversal at room temperature in unsubstituted AlN

Room temperature ferroelectricity in unsubstituted AlN films is studied to examine the role of cation substitution into wurtzite materials. AlN and (Al0.7Sc0.3)N films deposited on (111) 0.5 wt. % Nb-doped SrTiO3 have a (0001)-orientation with different in-plane lattice alignments with respect to those of the substrate, depending on the composition and the deposition temperature. The AlN films deposited at 450 °C showed complete ferroelectric switching above 140 °C but local polarization switching at room temperature because a dielectric breakdown occurred before complete switching, while full polarization reversal was observed at all measurement temperatures for (Al0.7Sc0.3)N. Low-temperature deposition, such as at 250 °C, significantly enhanced the dielectric breakdown field and also increased leakage current. As a result, sufficient polarization switching at room temperature was observed in the AlN film deposited at 250 °C. Positive-up/negative-down pulse measurements showed remanent polarization of 150 μC/cm2 and a coercive field of 8.3 MV/cm, in agreement with the theoretical value and temperature dependence observed for the AlN film deposited at 450 °C. The observed coercive field value lies on the line composed of the previously reported data in Sc concentration dependence. This tendency implies that the reduction in the coercive field is primarily attributable to the alteration of crystal lattice anisotropy caused by Sc.

Dynamic performance of newly developed environmentally friendly greases containing polysaccharide gums in rolling bearing

The present study explores the performance of novel vegetable oil-based greases containing polysaccharide gums as additives. Two series of greases with varying concentrations of gum acacia (GA) and guar gum (GG) are evaluated in a rolling bearing at various speeds and loads. The vibrations and shock pulse measurements (SPM) quantified the tribo-dynamics of the developed greases against two commercial greases used as the benchmark. The vibration and SPM assessment suggest that the newly developed eco-friendly greases are at par with the commercial ones; the performance varies with the concentration and type of gum. Where a cumulative effect of rheology and gum size seems to influence the vibrations, the entrainment of gums in the contact zone governs the SPM carpet values. The developed greases show great prospects as a sustainable, potential, and commercial alternative to existing environmentally unfriendly greases.

Early and Consistent CRS Detection Using Wearable Device for Remote Patient Monitoring Following CAR-T Therapy in Relapsed/Refractory Multiple Myeloma (RRMM): Early Results of an Investigator-Initiated Trial

The administration of Chimeric Antigen Receptor T-cell (CAR-T) therapy for relapsed refractory multiple myeloma (RRMM) predominantly takes place in the inpatient setting to monitor for adverse effects like cytokine release syndrome (CRS) and neurotoxicity leading to increased healthcare utilization, infection risk and patient discomfort. Shifting the administration model to the outpatient setting may improve patient experience, optimize hospital bed utilization and decrease costs, but requires an objective and reliable method for CRS detection to monitor patients remotely and safely. The feasibility of using a wearable device for detecting CRS following CAR-T therapy in RRMM was compared to standard of care (SoC) nursing-recorded vital signs in this investigator initiated clinical trial (IIT). Patients wore a wearable device that collected continuous measures of temperature, pulse, respiratory rate, and O2 saturation in addition to SoC while receiving CAR-T therapy from the day infusion to discharge. Changes in vital signs captured by the device were analyzed based on 2 thresholds: (i) CRS timestamps were tagged in wearable data when pt's temperature breached a fixed threshold of 38 0C ( Tf) defined as fever by the American Society of Transplantation and Cellular Therapy (ASTCT), and (ii) when pt's temperature breached an individualized threshold of 2 standard deviations above their baseline temperature ( Ti) [see Figure 1]. Outcomes were time to first detection of CRS in wearable data vs. SoC. Wearable adherence was the duration pts wore the device over the total monitoring period. To date, 34 pts were screened, 28 enrolled (82.3% uptake), 1 was excluded from the dataset because of concurrent COVID-19, and 2 pts with CRS were excluded from time to detection comparison because of wearable adherence <50% during high-risk windows (defined as the time period where CRS is expected per known data for the CAR-T product). Max CRS grades were 1 (17 pts), 2 (1 pt), 3 (2 pts), and 4 (1 pt); 5 pts did not have clinical CRS. Patients wore the device for a median of 13 (12-15) days out of a median of 15.5 (14-17) days of inpatient admission for CAR-T infusion. Median individualized temperature threshold was 37.4 (37-37.6) C. Wearable adherence was 64 (51 - 77) % and 72 (57 - 87) % for the overall monitoring and high-risk periods, respectively. The wearable detected the initial CRS events at a median of 22 (-43 - 113.5) min earlier than SoC with Tf and a median of 184 (53 - 312) mins earlier than SoC with Ti method. In the no CRS subgroup, false CRS detection occurred in 1 pt with the Tf and 2 pts with the Ti method. Preliminary results suggest that time to CRS detection by the wearable device preceded SoC detection by a median of 103 minutes corroborated by both threshold methods. Temperature thresholds calibrated to the baseline temperature of individual patients facilitate earlier detection of CRS than fixed thresholds per clinical/ASTCT criteria. While the low false detection rate in is encouraging, these may also potentially be attributed to subclinical events. Both pts who had “false positive” triggers breached their individualized temperature thresholds via device readings while only recording low-grade temperatures that did not meet clinical CRS criteria per ASTCT, indicating possible capture of subclinical events. The study showcases the utility of continuous remote patient vital signs monitoring by wearable devices in efficiently capturing CRS, including subclinical events, earlier than SoC. Objective and reliable CRS monitoring may help safely transition workflows to outpatient CAR-T administration models. Analysis of trends in cytokine biomarkers for early CRS detection signal(s) is currently underway. Cytokine signals, alone and in combination with device data, are planned to be incorporated into machine learning models to build a CRS prediction index in future analyses. Figure 1: Snapshot in time of the continuous temperature data generated by the wearable device after CAR-T infusion showing capture of cytokine release syndrome. – Ti (solid line) represents the median baseline temperature of the patient over the entire duration of the data capture by the wearable device – Tf (dotted line) represents the temperature threshold of 38 0C, the clinical definition of fever as per ASTCT – Black diamond: clinical CRS event, when temperature >38 0C as recorded by nursing

Fast low bias pulsed DC transport measurements for the investigation of low temperature transport effects in semiconductor devices

We present a setup for fast, low-bias (≤1mV) DC transport measurements with μs time resolution for high ohmic resistance (≈20kΩ) semiconducting samples. We discuss the circuitry and instrumentation for the measurement approach that can be applied to any kind of semiconductor device or (gated) two-dimensional material and demonstrate the main measurement artifacts in typical measurements by means of circuit simulation. Based on the latter, we present a simple two-step protocol for eliminating the measurement artifacts reliably. We demonstrate the technique by measuring the transitions between quantum Hall plateaus in the HgTe quantum wells and resolve plateaus as short-lived as 100 μs.

Language Nativeness Modulates Physiological Responses to Moral vs. Immoral Concepts in Chinese-English Bilinguals: Evidence from Event-Related Potential and Psychophysiological Measures.

Morality has been an integral part of social cognition and our daily life, and different languages may exert distinct impacts on human moral judgment. However, it remains unclear how moral concept is encoded in the bilingual brain. This study, therefore, aimed to explore the emotional and cognitive involvement of bilingual morality judgement by using combined event-related potential (ERP) and psychophysiological (including skin, heart, and pulse) measures. In the experiment, thirty-one Chinese-English bilingual participants were asked to make moral judgments in Chinese and English, respectively. Our results revealed increased early frontal N400 and decreased LPC in L1 moral concept encoding as compared to L2, suggesting that L1 was more reliant on automatic processes and emotions yet less on elaboration. In contrast, L2 moral and immoral concepts elicited enhanced LPC, decreased N400, and greater automatic psychophysiological electrocardiograph responses, which might reflect more elaborate processing despite blunted emotional responses and increased anxiety. Additionally, both behavioral and P200 data revealed a reliable immorality bias across languages. Our results were discussed in light of the dual-process framework of moral judgments and the (dis)embodiment of bilingual processing, which may advance our understanding of the interplay between language and morality as well as between emotion and cognition.

Development of a textronic system by machine embroidery for sportsmen

Numerous solutions for pulse measurement by athletes exist, most commonly in the form of watches or bands. However, some athletes do not tolerate or do not want additional devices on their bodies during exercise. This work aims to replace the existing commercial solutions with textile sensors embedded in clothing. Such a solution would increase comfort and facilitate physical activity. To select the best solution, four knitted fabrics were tested to select the one with the best parameters as a substrate for the system. Three different densities of the embroidery with electrically conductive thread 100%, 85% and 65% were also tested and in two sizes for bands and belts. Mechanical and utility tests were performed such as resistance to perspiration or tensile stress. All tests were carried out in an accredited laboratory, in accordance with applicable standards and our own methodology. The results showed the best material, embroidery density and embroidery size to create an airy, heat-dissipating, and durable textronic system for athletes. Prototype of the solution was created, and its operation was tested during simulation. Conducted tests of the conductive properties of embroidered materials confirm the possibility of making textronic sensors responding to the pulse. The knitted fabrics selected for the tests meet the requirements of sports materials for the parameters of thermal resistance and air permeability. The results showed the correct operation of the prototype.

The Role of Vacancy Dynamics in Two‐Dimensional Memristive Devices

AbstractTwo‐dimensional layered transition metal dichalcogenides (TMDCs) are promising memristive materials for neuromorphic computing systems. Despite extensive experimental work, the underlying switching mechanisms are still not understood, impeding progress in material and device functionality. This study reveals the dominant role of defect dynamics in the switching process of 2D TMDC materials. The switching process is governed by the formation and annihilation dynamics of a local vacancy depletion zone. It explains the distinct features of the device characteristics observed experimentally, including fundamentally different device behavior previously thought to originate from multiple mechanisms. Key influence factors are identified and discussed with a fully coupled and dynamic charge transport model for electrons, holes, and ionic point defects, including image‐charge‐induced Schottky barrier lowering (SBL). Thermal effects and local Joule heating are considered by coupling the transient heat transfer equation to the electronic properties. The model is validated with hysteresis and pulse measurements for various lateral 2D MoS2‐based devices, strongly corroborating the relevance of vacancy dynamics in TMDC devices and offering a new perspective on the switching mechanisms. The insights gained from this study can be used to extend the functional behavior of 2D TMDC memristive devices in future neuromorphic computing applications.

Self-referencing similariton-based spectral interferometry for ultrashort pulse complete characterization

Similariton is used to provide a reference for the characterization of ultrashort pulses by spectral interferometry. Measured pulse profiles are compared with autocorrelation measurements and cross-checked by spectrotemporal imaging technique based on similariton-induced temporal lens. The use of similariton makes the pulse measurement method self-referencing, substantially improving its application range, whilst preserving the simplicity of the principle and setup of the classic methods of spectral interferometry that require a reference pulse. Our comparative experimental study, carried out together with numerical simulations, provides the application range and limitations of the method and evidences the high precision of the similariton-based spectral interferometry.

Effects of rotational excitation on decay rates of long-lived Rydberg states in NO.

Nitric oxide (NO) molecules in pulsed supersonic beams have been excited to long-lived Rydberg-Stark states in series converging to the lowest vibrational level in the ground electronic state of NO+ with rotational quantum numbers N+ = 2, 4, and 6. The molecules in these excited states were then guided, or decelerated and trapped in a chip-based Rydberg-Stark decelerator, and detected in situ by pulsed electric field ionization. Time constants, reflecting the decay of molecules in N+ = 2 Rydberg-Stark states, with principal quantum numbers n between 38 and 44, from the electrostatic traps were measured to be ∼300μs. Molecules in Rydberg-Stark states with N+ = 4 and 6, and the same range of values of n were too short-lived to be trapped, but their decay time constants could be determined from complementary sets of delayed pulsed electric field ionization measurements to be ∼100 and ∼25 μs, respectively.

Bandpass filter and frequency-time mapping method for pulse measurement with optical delay.

The pulse signal's transients and low duty cycle characteristics lead to excessive omission and erroneous amplitude measurement in signal capture. We offer a combined microwave photonics frequency-time mapping and optical delay electrical pulse measurement system. Beneficial from the true delay of a long fiber with several paths, the pulse is extended to have a more significant duty cycle so as to boost the capturing possibility. We adopt the bandpass filter to avoid sampling the low-frequency range, prevent phase noise from affecting the signal measurement, and improve the signal-to-noise ratio (SNR). This solves the phase noise issue induced by multiple optical delay paths. The proof-of-concept experiments conduct that a 25 μs pulse with a 50 μs period is stretched to a continuous wave, and the SNR is improved by 7 dB.

Manipulation of Population Levels through Zeno-Type Measurements

We present a scheme, based on Bloch equations and Zeno-type measurements, that allows the control of the probability density evolution of the eigenstates of a V-type system. The equations are solved numerically and we present how the population in each level can be controlled using different sequences of “pulse measurements”. The entropy between the “measurement device” and the field used to perform the measurement process is evaluated for different strengths of such field, these calculations show that the entropy is maximized when we are in the Zeno regime. The results shown here unveil different possible strategies for controlling the population levels of a V-type system and could be implemented, for example, in trapped ions or RMN qubits.

Cell-to-cell variation beyond parameter analysis — Identification and correlation of processes in Lithium-Ion Batteries using a combined distribution of relaxation times analysis

Cell-to-cell variations inside a battery pack can result in inhomogeneities, leading to an accelerated, uneven aging. Until today these variations are solely quantified by parameter-based studies, which only offer a limited interpretability. To tackle this inconclusiveness, cell-to-cell variations and their effects on the electrode processes of lithium-ion batteries are investigated in this work. For this purpose 92 cells are characterized by impedance, pulse, and pseudo open-circuit voltage measurements, and the data obtained is compiled as publicly available data set. The data is examined by a holistic distribution of relaxation times analysis, comprising complementary distribution of relaxation times approaches. This enables a reliable identification of process variations between cells. First, the confidence intervals of both the raw data and the distribution of relaxation times are examined. Subsequently, the individual processes, their characteristic time constants, and their polarization are determined. The analysis reveals that a normal distribution only applies in one of the examined cases and can even be excluded in four cases. Finally, a correlation analysis is conducted, allowing the categorization of the identified processes into cell winding, electrochemical interface processes, and solid-state diffusion. The potential physicochemical reasons behind are discussed and the work thus contributes to a deeper understanding of cell-to-cell variations.

Cycle-to-cycle variability analysis of Ti/Al2O3-based memristors

In this work, an experimental analysis of the resistive switching behavior of TiN/Ti/Al2O3/W memristors is presented. The main focus is on the analysis of the variability of the key parameters during long series of cycles, using both sweep and pulsed voltage measurement sequences. In addition, the correlation of the resistive switching parameters between subsequent cycles has been investigated. The results demonstrate that memristors based on Ti/Al2O3 exhibit a low cycle-to-cycle variability between consecutive cycles, indicating their potential use for emerging applications.

Development of a novel wrist pulse system for early diagnosis of pathogenic bacterial infections using optimized feature selection with machine learning approaches

Pelvic inflammatory disease (PID) and urinary tract infections (UTI) are two Pathogenic bacterial infections. PID affects the female reproductive system, whereas UTI affects the urine system. Females are more vulnerable to both forms of illnesses and challenging to detect simultaneously due to similar symptoms. Many Clinical procedures have previously been used to diagnose the diseases, but they are painful, costly, prone to radiation, and invasive. Therefore, this paper proposed the Ayurvedic and Traditional Chinese Medicine [TCM] based wrist pulse measurement to diagnose these bacterial infections non-invasively. An Artery tonometry-based test prototype was designed to measure the pulse signals at three doshas (Vata, Pitta, Kapha) locations on the radial artery under variable static force. The data is recorded at an intermediate force level to get maximum accuracy. Signals feature viz., time domain feature, autoregressive (AR) model features, approximation entropy, sample entropy, and multiscale entropy have been calculated. Further, the efficiency of the machine learning model is enhanced through optimization-based feature selection techniques. Three different optimization-based feature selection, viz., whale optimization (WOA), ant colony optimization (ACO), and proposed binary Greywolf optimization (BGWO), has been proposed to acquire the optimized features subsets for accurate classification of disease subjects. These subsets have been used by popular machine learning techniques to classify the PID and UTI. The results of the experiment demonstrate that as the static force changed, the wrist pulse signal first increased to an intermediate force level and then decreased. Second, the classification accuracy of the machine learning model with feature selection is more than conventional feature classification. Third, the wrist pulse analysis (WPA) shows the maximum accuracy in comparison to conventional clinical PID diagnosis, where Vata dosha has the highest classification accuracy (94.1%) when using BGWO-SVM, followed by Pitta dosha (88.2%) when using BGWO-BNN. Similarly, specificity has been used for UTI classification, where Vata dosha has the highest specificity of 100% with BGWO-SVM, followed by pitta dosha with 83.3% BGWO-BNN. Finally, three dosha classification findings demonstrate that Vata and Pitta doshas have been more significantly impacted, as they have the highest classification accuracy compared to conventional clinical diagnosis, which produces similar results consistent with ayurvedic literature. Therefore, WPA can provide a unique diagnostic method for early PID/UTI identification.

Pulsed wave Doppler ultrasound: Accuracy, variability, and impact of acquisition parameters on flow measurements.

Pulsed wave Doppler ultrasound is a useful modality for assessing vascular health as it quantifies blood flow characteristics. To facilitate accurate diagnosis, accuracy and consistency of this modality should be assessed through Doppler quality assurance (QA). The purpose of this study was to characterize the accuracy, reproducibility, and inter-scanner variability of ultrasound flow velocity measurements via a flow phantom, with a focus on the effect of systematic acquisition parameters on measured flow velocity accuracy. Using a manufacturer-calibrated flow phantom, pulsed wave measurements were acquired on five clinical systems (iU22, Philips) with three models of transducers, including both linear and curvilinear models. The peak and mean flow velocities were estimated by vendor-supplied spectral analysis tools. To investigate intra- and inter-scanner variability, measurements were repeated using each scanner-transducer pair under a standardized set of conditions. Inter-scanner variability was assessed using ANOVA. Flow velocity accuracy was investigated by mean absolute percentage error. The impacts of receive gain, measurement depth, and beam steering on measured flow velocity accuracy were examined by varying each parameter over its available range and comparing to the ground truth flow velocity. Inter-scanner variability was statistically significant for peak flow measurements made using both linear and curvilinear transducers, though absolute differences in measured velocity were small. Inter-scanner variability was not statistically significant for mean flow velocity. Receive gain, measurement depth, and beam steering were all found to impact the accuracy of measured flow characteristics for linear transducers. Accuracy of the flow measurements made with the curvilinear transducer demonstrated high consistency to changes in receive gain at a constant depth, though were impacted by increasing the measurement depth. Carefully and consistently selected acquisition and set-up parameters are essential in order to establish a reliable and meaningful QA program.

A randomized measurement toolbox for an interacting Rydberg-atom quantum simulator

We present a toolbox to probe quantum many-body states implemented on Rydberg-atoms quantum hardware via randomized measurements. We illustrate the efficacy of this measurement toolbox in the context of probing entanglement, via the estimation of the purity, and of verifying a ground-state preparation using measurements of the Hamiltonian variance. To achieve this goal, we develop and discuss in detail a protocol to realize independent, local unitary rotations. We benchmark the protocol by investigating the ground state of the one-dimensional Su–Schrieffer–Heeger model, recently realized on a chain of Rydberg atom, and the state resulting after a sudden quench in a staggered XY chain. We probe the robustness of our toolbox by taking into account experimental imperfections, such as pulse fluctuations and measurement errors.

Trade-off between gate leakage current and threshold voltage stability in power HEMTs during ON-state and OFF-state stress

We present a detailed investigation of the impact of electron gate leakage on the threshold voltage stability of normally-off GaN HEMTs with p-GaN gate. The analysis is based on combined DC, pulsed and transient measurements, carried out on two test wafers with different gate processes, resulting in different levels of gate leakage current. The key results demonstrate: (a) the existence of four different charge-trapping processes, whose interplay determines the sign and amplitude of the threshold voltage variation; (b) a reasonable increase in gate leakage is beneficial for eliminating the negative threshold voltage instability under positive gate bias, and for substantially reducing the positive threshold shift under off-state stress. Furthermore, (c) we present a proper characterization methodology for device understanding.