Measurement Window Research Articles

A Parameter-Oriented FFT Signal Processing App

In power systems, some components such as harmonics / interharmonics and noise arise in electrical signals due to varying sources and loads, resulting in changes in the purity of the electrical signal. Therefore, continuous monitoring and accurate analysis of electrical signals become mandatory. One of the common methods in this field is the Fast Fourier Transform (FFT), which subjects electrical signals to continuous analysis through sliding windows at the intervals formed by the standard of IEC-61000-4-7. From this analysis, various parameters are derived and compared with the threshold values specified in other standard, the IEEE-1159. However, due to variational field conditions, as well as factors such as frequencies of sampling, main, and additional components, measurement window, and Signal-to-Noise Ratio (SNR), various measurement errors, occur. These difficulties further complicate the already difficult task of accurate measurement in variable conditions and can lead to errors in preventive measures and control procedures. It is therefore of great importance to gain an understanding of the effects of these parameters and to implement improvements to the methods accordingly. This study emphasizes the significance of parameter selection for FFT and presents an investigation of FFT responses in terms of different parameters. Furthermore, it presents measurement errors according to changes in the signal and presents a basic interface design showing these errors. It was found that even small changes, such as a 1/2000 change in the sampling frequency, a 0.5 Hz shift in the fundamental frequency, or a 1/1000 difference in the measurement window, resulted in significant errors. These findings highlight the necessity of judicious parameter selection for accurate computation and signal monitoring and demonstrate that improvements in the FFT method are needed to adapt to changing conditions.

A low-cost, open-source cylindrical Couette rheometer

Rheology describes the flow of fluids from food and plastics, to coatings, adhesives, and 3D printing inks, and is commonly denoted by viscosity alone as a simplification. While viscometers adequately probe Newtonian (constant) viscosity, most fluids have complex viscosity, requiring tests over multiple shear rates, and transient measurements. As a result, rheometers are typically large, expensive, and require additional infrastructure (e.g., gas lines), rendering them inaccessible for regular use by many individuals, small organizations, and educators. Here, we introduce a low-cost (under USD$200 bill of materials) Open Source Rheometer (OSR), constructed entirely from thermoplastic 3D printed components and off-the-shelf electromechanical components. A sample fluid rests in a cup while a micro stepping motor rotates a tool inside the cup, applying strain-controlled shear flow. A loadcell measures reaction torque exerted on the cup, and viscosity is calculated. To establish the measurement range, the viscosity of four Newtonian samples of 0.1–10 Pa.s were measured with the OSR and compared to benchmark values from a laboratory rheometer, showing under 23% error. Building on this, flow curves of three complex fluids – a microgel (hand sanitizer), foam (Gillette), and biopolymer solution (1% Xanthan Gum) – were measured with a similar error range. Stress relaxation, a transient test, was demonstrated on the biopolymer solution to extract the nonlinear damping function. We finally include detailed exposition of measurement windows, sources of error, and future design suggestions. The OSR cost is ∼1/25th that of commercially available devices with comparable minimum torque (200 µN.m), and provides a fully open-source platform for further innovation in customized rheometry.

Unprecedented Photoinduced‐Electron‐Transfer Probe with a Turn‐ON Chemiluminescence Mode‐of‐Action

AbstractPeT‐based fluorescent probes were demonstrated to be powerful tools for detection and imaging, owing to their significant fluorescence enhancement in response to specific targets. While numerous examples of fluorescence‐based PeT have been frequently reported, there is not even a single example of a PeT probe that operates via a chemiluminescence mode. Here we report the first PeT‐based turn‐on probe that acts via a chemiluminescent operation mode. We designed, synthesized, and evaluated a novel chemiluminescent probe, featuring a PeT‐based turn‐on mechanism. The probe consists of a phenoxy‐1,2‐dioxetane, linked to an azide unit that acts as a PeT quencher. Upon cycloaddition of a strained cycloalkyne with the azide, a triazole‐dioxetane is formed, which undergoes relatively slow chemiexcitation, resulting in a measurement window with an exceptionally high signal‐to‐noise ratio (over 5000‐fold). The PeT‐dioxetane probe could effectively detect and image two model proteins labeled with strained cycloalkyne units (Myc‐DBCO and Max‐DBCO) through either NHS or maleimide conjugations. Comparative analysis shows that our PeT‐based chemiluminescent probe significantly outperforms a commercially available fluorescent analog. We anticipate that the insights gained from this study will facilitate the development of additional chemiluminescent probes utilizing various PeT‐quenching pathways.

Unprecedented Photoinduced-Electron-Transfer Probe with a Turn-ON Chemiluminescence Mode-of-Action.

PeT-based fluorescent probes were demonstrated to be powerful tools for detection and imaging, owing to their significant fluorescence enhancement in response to specific targets. While numerous examples of fluorescence-based PeT have been frequently reported, there is not even a single example of a PeT probe that operates via a chemiluminescence mode. Here we report the first PeT-based turn-on probe that acts via a chemiluminescent operation mode. We designed, synthesized, and evaluated a novel chemiluminescent probe, featuring a PeT-based turn-on mechanism. The probe consists of a phenoxy-1,2-dioxetane, linked to an azide unit that acts as a PeT quencher. Upon cycloaddition of a strained cycloalkyne with the azide, a triazole-dioxetane is formed, which undergoes relatively slow chemiexcitation, resulting in a measurement window with an exceptionally high signal-to-noise ratio (over 5000-fold). The PeT-dioxetane probe could effectively detect and image two model proteins labeled with strained cycloalkyne units (Myc-DBCO and Max-DBCO) through either NHS or maleimide conjugations. Comparative analysis shows that our PeT-based chemiluminescent probe significantly outperforms a commercially available fluorescent analog. We anticipate that the insights gained from this study will facilitate the development of additional chemiluminescent probes utilizing various PeT-quenching pathways.

Identification of a Non‐Commensurate Fractional‐Order Nonlinear System Based on the Separation Scheme

ABSTRACTThis article is aimed to study the parameter estimation problems of a non‐commensurate fractional‐order system with saturation and dead‐zone nonlinearity. In order to reduce the structural complexity of the system, the model separation scheme is used to decompose the fractional‐order nonlinear system into two subsystems, one includes the parameters of the linear part and the other includes the parameters of the nonlinear part. Then, we derive an auxiliary model separable gradient‐based iterative algorithm with the help of the model separation scheme. In addition, to improve the utilization of the real time information, an auxiliary model separable multi‐innovation gradient‐based iterative algorithm is presented based on the sliding measurement window. Finally, the feasibility of the presented algorithms is validated by numerical simulations.

REVIEW: Nonlinear shear rheometry: Brief history, recent progress, and challenges

High-shear rate rotational rheometry provides access to the fast nonlinear dynamics of soft materials and, particularly, their shear stress (exhibiting shear thinning and/or thickening) as well as the first and second normal stress differences, along with their time-dependent behavior. These material functions are valuable for understanding a material's processing performance and constitutive behavior and, hence, for designing new materials with desired rheology. However, their accurate measurement has been one of the most formidable challenges in rheometry. Here, we provide an overview of the different approaches used, along with their merits and drawbacks, while we discuss practical guidelines for the implementation of measurement protocols. We focus on the development and use of cone-partitioned plate fixtures, which have been shown to provide reliable data over a wide range of Weissenberg numbers, when properly used. Furthermore, this review presents selected applications and results from recent developments, identifies operating measurement windows, discusses new capabilities and open problems, and, finally, it provides perspectives for further developments.

Determination of trace uranium concentrations in spent‐fuel reprocessing using online graphite crystal pre‐diffraction energy‐dispersive x‐ray fluorescence

AbstractAn online graphite crystal pre‐diffraction x‐ray fluorescence technique was developed for accurate real‐time detection of trace uranium concentrations in spent‐fuel reprocessing streams. Online analysis for determining uranium concentrations was established. The device was equipped with measurement windows in both the flow cell and a side wall of the glove box. X‐ray tubes and detectors were arranged outside the glove box, and the process stream flowing through the flow cell was measured through the measurement window. A cylindrical highly oriented pyrolytic graphite crystal was located in front of the detector to improve detection efficiency and to provide monochromatic uranium‐characteristic x‐rays. At the same time, the device could perform remote online automatic calibration. The uranium detection limit in a kerosene solution was 0.08 mg/L, and the quantitative limit was 0.27 mg/L. The detection limit in a nitric acid solution was 0.11 mg/L, and the quantitative limit was 0.37 mg/L. The relative standard deviation of measuring 0.5 mg/L uranium was less than 10%, which greatly improved online monitoring of trace uranium in spent‐fuel reprocessing samples.

SeHCAT retention measurements may be compromised by traces of 177 Lu/ 177m Lu more than 90 days after 177 Lu-DOTATATE was administered.

[ 75 Se]tauroselcholic acid (SeHCAT) retention measurement provides a noninvasive test for bile acid diarrhea (BAD); however, it is sensitive to the presence of other radionuclides. Two SeHCAT patients at the Royal Free Hospital (RFH) had significant discrepancies between the lower photopeak (111-159 keV) and central photopeak (242-296 keV) windows, indicating contamination with a radionuclide other than 75 Selenium. These patients had received lutetium-177 oxodotreotide ( 177 Lu-DOTATATE) therapy 98 and 151 days before their SeHCAT tests. Traces of 177 Lu may be retained longer than typically modeled, along with the contaminant 177m Lu. This work includes a retrospective audit to examine the prevalence of SeHCAT tests being affected by 177 Lu and phantom measurements to investigate the potential impact. Of 579 patients who received 177 Lu-DOTATATE therapy at our center, 11 subsequently attended for a SeHCAT test. The two previously identified patients may have had compromised SeHCAT results; however, the other patients had longer intervals between their therapy and test, and their tests are believed to be valid. Spectra were acquired from a phantom containing either a SeHCAT capsule or a mixture of 177 Lu/ 177m Lu representative of a patient >90 days after their treatment. The SeHCAT spectrum was scaled to produce simulated day-7 spectra, and the SeHCAT retention that would have been calculated if 177 Lu/ 177m Lu were present was determined. All SeHCAT measurement windows are affected by the 177 Lu/ 177m Lu, producing clinically significant errors. Patients requiring SeHCAT testing should be asked whether they have ever received 177 Lu-DOTATATE. Patient-specific background measurements may be useful for checking for significant levels of other radionuclides.

Improving the mechanical, spectroscopic and laser ablation characteristics of UDMA-MMA copolymers using a titanocene photoinitiator

We have shown that the Irgacure 784 titanocene photoinitiator can be advantageously used to improve the light absorption, mechanical and nanosecond-regime laser ablation properties of urethane dimethacrylate (UDMA)-methyl methacrylate (MMA) polymer blends with photopolymerization using curing with green (520–525 nm) light. The hardness was found to be significantly higher (0.25–0.29 GPa) than that of other UDMA polymer blends photopolymerized using other initiator systems. The established 48–63 % degree of conversion is also comparable to that of similar other blends and is useful in many applications. The laser ablation and laser-induced breakdown spectroscopy (LIBS) properties of these polymers were studied at 266 and 532 nm laser wavelengths. The polymers showed consistently good laser ablation characteristics (reproducible, well-defined, shallow craters) at 266 nm wavelength, whereas at 532 nm, extensive carbonization and strong photothermal effects were observed. LIBS spectra of the blend shows lines of C, H, O, N and Ti as well as C2 and CN bands, but provide many spectral windows for interference-free analytical measurements. Our findings indicate that UDMA-MMA polymer blends can be good candidates as target matrices for laser ablation-based measurements in the UV or Vis range, in applications like analytical spectroscopy or laser-initiated fusion research.

Automated analysis of the void structure in hardened concrete based on shape from focus

The quality of the air void system is essential for the frost resistance of concrete. Therefore, it is crucial to assess the quality of the air void system in hardened concrete in an appropriate way. In this study, the shape from focus (SFF) method is applied to identify the focused image of each point on the polished surface of hardened concrete and thereby acquire the depth information of the entire surface. The performance of various focus measure operators and window sizes is evaluated. Thereafter, the selected focus measure operator and window size are applied for the SFF analysis of all samples. Based on the obtained depth map, the voids are identified, and the void parameters of the hardened concrete are determined by an automated procedure. The main advantage of the SFF method is that it is possible to carry out an automated air void analysis without contrast enhancement.

Using Adaptive Imaging Parameters to Improve PEGylated Ultrasmall Iron Oxide Nanoparticles-Enhanced Magnetic Resonance Angiography.

The PEGylated ultrasmall iron oxide nanoparticles (PUSIONPs) exhibit longer blood residence time and better biodegradability than conventional gadolinium-based contrast agents (GBCAs), enabling prolonged acquisitions in contrast-enhanced magnetic resonance angiography (CE-MRA) applications. The image quality of CE-MRA is dependent on the contrast agent concentration and the parameters of the pulse sequences. Here, a closed-form mathematical model is demonstrated and validated to automatically optimize the concentration, echo time (TE), repetition time (TR) and flip angle (FA). The pharmacokinetic studies are performed to estimate the dynamic intravascular concentrations within 12h postinjection, and the adaptive concentration-dependent sequence parameters are determined to achieve optimal signal enhancement during a prolonged measurement window. The presented model is tested on phantom and in vivo rat images acquired from a 3T scanner. Imaging results demonstrate excellent agreement between experimental measurements and theoretical predictions, and the adaptive sequence parameters obtain better signal enhancement than the fixed ones. The low-dose PUSIONPs (0.03mmol kg-1 and 0.05mmol kg-1) give a comparable signal intensity to the high-dose one (0.10mmol kg-1) within 2h postinjection. The presented mathematical model provides guidance for the optimization of the concentration and sequence parameters in PUSIONPs-enhanced MRA, and has great potential for further clinical translation.

GLAD-M35: a joint P and S global tomographic model with uncertainty quantification

SUMMARY We present our third and final generation joint P and S global adjoint tomography (GLAD) model, GLAD-M35, and quantify its uncertainty based on a low-rank approximation of the inverse Hessian. Starting from our second-generation model, GLAD-M25, we added 680 new earthquakes to the database for a total of 2160 events. New P-wave categories are included to compensate for the imbalance between P- and S-wave measurements, and we enhanced the window selection algorithm to include more major-arc phases, providing better constraints on the structure of the deep mantle and more than doubling the number of measurement windows to 40 million. Two stages of a Broyden–Fletcher–Goldfarb–Shanno (BFGS) quasi-Newton inversion were performed, each comprising five iterations. With this BFGS update history, we determine the model’s standard deviation and resolution length through randomized singular value decomposition.

Effect of different Volumes of exercise on skin temperature responses over the following 24 hours

Skin temperature responses have been advocated to indicate exercise-induced muscle soreness and recovery status. While the evidence is contradictory, we hypothesize that the presence of muscle damage and the time window of measurement are confounding factors in the skin temperature response. The objective was to determine whether skin temperature is influenced by different workloads and the time course of temperature measurements over the following 24 h. 24 trained male military were assigned to one of three groups: GC group (n = 8) serving as control not performing exercises, GE group (n = 8) performing a simulated military combat protocol in an exercise track with different obstacles but designed not to elicit muscle damage, and the GEMD group (n = 8) performing the simulated military combat protocol plus 5 sets of 20 drop jumps, with 10-sec between repetitions and with 2-min of rest between sets aiming to induce muscle damage. Skin temperature was measured using infrared thermography before exercise (Pre) and 4 (Post4h), 8 (Post8h) and 24h (Post24h) post-exercise. Perception of pain (DOMS) was evaluated Pre, Post24h, and Post48h, and countermovement jump height was evaluated at Pre and Post24h. DOMS did not differ between groups in the Pre and Post24h measures but GEMD presented higher DOMS than the other groups at Post48h (p < 0.001 and large effect size). Jump height did not differ for GEMD and GC, and GE presented higher jump height at Post24h than GC (p = 0.02 and large effect size). Skin temperature responses of GEMD and GG were similar in all measurement moments (p > 0.22), and GE presented higher skin temperature than the GC and the GEMD groups at Post24h (p < 0.01 and large effect sizes). In conclusion, although physical exercise elicits higher skin temperature that lasts up to 24 h following the efforts, muscle soreness depresses this response.

Real-time transient stability early warning system using Graph Attention Networks

In this paper, a classifier based early warning system is designed, trained and tested based on time-series of Phasor Measurement Unit (PMU) measurements at all buses in a power system. The classifier is based on a novel combination of Graph Attention Networks and Long Short-Term memories, and is trained to label power system data in the form of captured windows of PMU measurements. These labels are then used to provide early warning for transient instability. The classifier is trained and tested data from simulations of the Nordic44 test system, and includes extensive topological variations under two different load levels. It is found that accurate early warnings can be provided, but the quality of prediction is highly dependent on specific power system characteristics, such as how quickly the power system responds to transient disturbances.

Reliable Determination of Contact Angle from the Liquid Fence.

Traditional methods of measuring contact angles often face difficulties in precisely defining the three-phase contact points. A novel method for accurately defining three-phase contact points based on liquid fences is proposed in this article. The tested liquid is placed in a cubic liquid fence composed of a pair of narrow strips of the tested solid and a pair of transparent wide strips. The transparent wide strip serves as the measurement window, and the surface tension of the liquid on it can be almost ignored. In experimental measurements, the horizontal coordinates of the end points of the liquid profile are fixed by the liquid fence, thus determining the horizontal coordinates of the three-phase contact points, which helps to accurately survey the contact angle. Additionally, since the parameters of the liquid fence are known, the size of the contact angle can also be calculated by measuring the height of the liquid level dome inside the liquid fence. Using the electric wetting effect as an example, we experimentally extracted a series of liquid contour maps with circular tops and square columns under varying voltages. The relationship curve between contact angle and voltage variation was obtained using the above methods, and a contact angle variation tendency seemed to agree well with the theoretical value.

Assessment of Mitochondrial Respiration During Hypothermic Storage of Liver Biopsies Following Normothermic Machine Perfusion

Organ quality can be assessed prior to transplantation, during normothermic machine perfusion (NMP) of the liver. Evaluation of mitochondrial function by high-resolution respirometry (HRR) may serve as a viability assessment concept in this setting. Freshly collected tissue is considered as optimal sample for HRR, but due to technical and personnel requirements, more flexible and schedulable measurements are needed. However, the impact of cold storage following NMP before processing biopsy samples for mitochondrial analysis remains unknown. We aimed at establishing an appropriate storage protocol of liver biopsies for HRR. Wedge biopsies of 5 human livers during NMP were obtained and assessed by HRR. Analysis was performed after 0, 4, 8, and 12 h of hypothermic storage (HTS) in HTK organ preservation solution at 4°C. With HTS up to 4 h, mitochondrial performance did not decrease in HTS samples compared with 0 h (OXPHOS, 44.62 [34.75–60.15] pmol·s−1·mg wet mass−1 vs. 43.73 [40.69–57.71], median [IQR], p &amp;gt; 0.999). However, at HTS beyond 4 h, mitochondrial respiration decreased. We conclude that HTS can be safely applied for extending the biopsy measurement window for up to 4 h to determine organ quality, but also that human liver respiration degrades beyond 4 h HTS following NMP.

Distance Measurement of Contra-Rotating Rotor Blades with Ultrasonic Transducers.

Coaxial rotor helicopters have great potential in civilian and commercial uses, with many advantages, but challenges remain in the accurate measurement of rotor blades' distance to prevent blade collision. In this paper, a blade tip distance measurement method based on ultrasonic measurement window and phase triggering is proposed, and the triggering time of the transmitter is studied. Due to the complexity of the measured signal, bandpass filtering and a time-of-flight (TOF) estimation based on the power density of the received signal are utilised. The method is tested on an experimental test platform with a pair of 200 kHz ultrasonic transducers. The experimental results show that the maximum ranging error is less than 1.0% for the blade tip distance in a range of 100-1000 mm. Compared with the amplitude threshold method, the proposed TOF estimation method works well on the received signal with a low SNR and improves the ranging accuracy by about 5 mm when the blade tip distance is larger than 500 mm. This study provides a good reference for the accurate measurement of rotor blade tip distance, and gives a solution for ranging high-speed rotating objects.

Binary multi-frequency signal for accurate and rapid electrochemical impedance spectroscopy acquisition in lithium-ion batteries

Electrochemical Impedance Spectroscopy (EIS) plays a crucial role in characterizing the internal electrochemical states of lithium-ion batteries and proves to be effective for estimating battery states. Traditional EIS measurement, however, requires expensive electrochemical workstations with time-consuming signal injection, especially in low-frequency regions, thus limiting its practical applications. Here we show that applying our proposed pulse-like Binary Multi-Frequency Signals (BMFS) as the excitation signal in the EIS measurement, which simultaneously possesses numerous frequency components and maintains high energy at each frequency component, will significantly improve test speed while retaining accuracy. The applicability of the BMFS under various cathode material types, including nickel cobalt manganese (NCM), lithium cobalt oxide (LCO), and lithium iron phosphate (LFP) is demonstrated. The robustness of the signal is experimentally verified through varying C-rates and measurement window lengths. The BMFS, requiring only 30 s per test, can achieve test results with an amplitude error of 1% and a phase error of 1° as compared with those obtained from traditional EIS tests. Moreover, BMFS can also be applied in online EIS measurement scenarios, favorable for real-world applications. This work enables accurate and rapid acquisition of EIS results, which is currently expensive and time-consuming to obtain, ensuring a faster and more nuanced characterization of the internal states of many battery systems in an affordable and accessible manner, especially in data-driven and machine-learning approaches.

Study of erythrocyte sedimentation in human blood through the photoacoustic signals analysis

IntroductionIn this study, we utilized the pulsed photoacoustic (PA) technique to analyze globular sedimentation in whole human blood, with a focus on distinguishing between healthy individuals and those with hemolytic anemia. MethodsBlood samples were collected from both healthy individuals (women and men) and those with hemolytic anemia, and temporal and spectral parameters of PA signals were employed for analysis. ResultsSignificant differences (p < 0.05) were observed in PA metrics between the two groups. The proposed spectral analysis allowed significant differentiation within a 25-minute measurement window. Anemic blood samples exhibited higher erythrocyte sedimentation rate (ESR) values, indicating increased erythrocyte aggregation. DiscussionThis study underscores the potential of PA signal analysis in ESR assessment as an efficient method for distinguishing between healthy and anemic blood, surpassing traditional approaches. It represents a promising contribution to the development of precise and sensitive techniques for analyzing human blood samples in clinical settings.

Diagnostic accuracy of left ventricular outflow tract velocity time integral versus inferior vena cava collapsibility index in predicting post-induction hypotension during general anesthesia: an observational study.

Point of care ultrasound (POCUS) is being explored for dynamic measurements like inferior vena cava collapsibility index (IVC-CI) and left ventricular outflow tract velocity time integral (LVOT-VTI) to guide anesthesiologists in predicting fluid responsiveness in the preoperative period and in treating post-induction hypotension (PIH) with varying accuracy. In this prospective, observational study on included 100 adult patients undergoing elective surgery under general anesthesia, the LVOT-VTI and IVC-CI measurements were performed in the preoperative room 15 minutes prior to surgery, and PIH was measured for 20 minutes in the post-induction period. The incidence of PIH was 24%. The area under the curve, sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of the two techniques at 95% confidence interval was 0.613, 30.4%, 93.3%, 58.3%, 81.4%, 73.6% for IVC-CI and 0.853, 83.3%, 80.3%, 57.1%, 93.8%, 77.4% for LVOT-VTI, respectively. In multivariate analysis, the cutoff value for IVC-CI was >51.5 and for LVOT-VTI it was ≤17.45 for predicting PIH with odd ratio [OR] of 8.491 (P=0.025) for IVCCI and OR of 17.427 (P<0.001) for LVOT. LVOT-VTI assessment was possible in all the patients, while 10% of patients were having poor window for IVC measurements. We recommend the use of POCUS using LVOT-VTI or IVC-CI to predict PIH, to decrease the morbidity of patients undergoing surgery. Out of these, we recommend LVOT-VTI measurements as it has showed a better diagnostic accuracy (77.4%) with no failure rate.