Phase Angle Research Articles

Prediction of Clinically-Relevant Postoperative Pancreatic Fistula after pancreatoduodenectomy based on Multi-frequency Magnetic Resonance Elastography.

Clinically relevant postoperative pancreatic fistula (CR-POPF) is the major complication of pancreatoduodenectomy, and the pancreatic texture is one of the potential affecting factors. Multi-frequency Magnetic Resonance Elastography (MRE) is a novel technique for measuring stiffness of tissue, while its value in predicting CR-POPF preoperatively has not been well-documented. Seventy patients who underwent multi-frequency MRE before pancreatoduodenectomy between July 2021 and April 2024 were retrospectively recruited into the study. The parameter of MRE, shear wave speed (c) and phase angle (φ), and clinical data were collected. Logistic regression and the receiver operating characteristic curve (ROC) analyses were used to assess the performance of multi-frequency MRE in predicting CR-POPF. CR-POPF was developed in 14 out of 70 patients (20%), all categorized as Grade B. CR-POPF group had significantly lower c (1.339±0.210m/s) and longer hospital stays (21±22days) than no CR-POPF group. The MRE parameters, c and φ were moderately correlated with pancreas stiffness (eta2 for φ =0.189, eta2 for c =0.106). Dilated major pancreatic duct (MPD) (≥3mm) and higher c were independently associated with lower risk of CR-POPF in univariant and multivariant analysis (odds ratio for c = 0.041, 95%CI: 0.002~0.879, odds ratio for dilated MPD: 0.129, 95%CI: 0.022~0.768). The AUC of the predictive model based on c and MPD diameter was 0.786, which was better than Fistula Risk Score (FRS) (AUC=0.587) and alternative Fistula Risk Score (a-FRS) (AUC=0.556) in our center, with DeLong's test p= 0.028 and p=0.002 respectively. The MRE parameters were associated with pancreatic stiffness, and c was an independent predictor for CR-POPF after pancreatoduodenectomy.

Visible Spectral Atlas of Geostationary Satellites from Tucson, AZ for Differentiating Between Natural and Artificial Objects

As near-Earth object (NEO) surveys continue to search for smaller NEOs, they will also detect an increasing number of temporarily captured objects, or minimoons, in geocentric orbital space. Derelict spacecraft and debris in Earth orbit and cislunar space can be mistaken for minimoons, but spectral characterization can distinguish between the two categories of objects. However, systematic noncompositional effects due to nightly and seasonal phase angle changes on artificial objects need to be quantified before such distinctions can be made. These effects have been studied on small solar system bodies, but very little on artificial bodies. We present the reduced data of our multiyear visible wavelength (450–950 nm) spectral campaign of the geostationary Earth-orbiting (GEO) satellite belt from Tucson, AZ, and include comparisons to relevant planetary materials. Although some bus types have steeper spectral slopes than planetary materials, certain bus type spectral features can be confused for planetary materials. One example is a rollover at red wavelengths in the Eurostar-3000 bus-type spectrum that appears similar to mineralogical absorption bands on S- and L-type asteroids. Observations include a total of 96 unique GEO satellites across 192 separate nights from 2020 to 2022. A select subset of GEO satellites is repeatedly observed to measure seasonal variations. Our methods for data acquisition, processing, and cleaning are outlined in this paper. A summary of the atlas shows the full night median spectrum with phase variations and a lightcurve of brightness versus phase angle for each of the 284 sets of data collected.

Altered inter-segmental coordination in athletes with a history of concussion

ABSTRACT Concussion-recovered athletes have a higher risk of injury following return to sport. This study investigated the effect of history of concussion on the pattern and variability of inter-segmental coordination in athletes during squat jumps and timed squat and hinge tasks. A human pose estimation algorithm was applied to videos of 111 athletes (72 with no history of concussion (NOHX), 9 within 1 year of concussion (CONC1), 30 more than one-year post-concussion (CONC2) performing a series of movement tasks. Continuous relative phase metrics, calculated from phase angles of two contiguous segments, were used to evaluate inter-segmental coordination. Linear models were used to evaluate the causal effect of concussion group on hip, knee, and ankle coordination and repetition duration for each task. CONC1 affected repetition duration and knee and hip coordination and variability, while CONC2 influenced knee coordination. The findings suggest that concussion may have long-term persisting effects on lower-limb inter-segmental coordination in athletes.

Dynamic Unbalance Identification in Steady-State Rotating Machinery: A Hybrid Methodology Integrating Physical and Data-Driven Techniques

Rotating machinery plays a strategic role in key industrial sectors, making its analysis a subject of great interest for both academia and industry. Effective maintenance planning for this equipment is essential for asset management and for meeting current industrial requirements. To address this demand, this work presents a novel unbalance identification approach based on a digital representation of a rotating machine's dynamic behavior in relation to the development of specific faults. A hybrid methodology is proposed, integrating Finite Element Modeling, a Kalman Filter for parameter estimation, and Referenced Moving Window Principal Component Analysis. This Principal Component Analysis extension enhances vibration pattern recognition, enabling accurate fault quantification directly from slight changes in the system's steady-state behavior. The methodology uniquely eliminates the need for phase angle measurements, facilitating continuous monitoring of unbalance progression in steady-state conditions. Two case studies demonstrate the methodology's potential: one utilizing synthetic data from a Floating Production Storage and Offloading centrifugal compressor unit, and the other based on real data from a hydroelectric turbine-generator. These studies illustrate the integration of computational modeling, data-driven analysis, and monitored vibration data, achieving robust and accurate unbalance identification. This approach provides valuable insights into current capabilities and opens promising pathways for future applications, particularly in the digital twin domain for rotating machinery.

Environmentally friendly high-content polyurethane modified asphalt: Workability evaluation and early performance evolution

High-content polyurethane modified asphalt (HPMA) has ignited the enthusiasm of researchers due to its low-carbon characteristics and excellent performance. The workability and service performance of HPMA are both affected by complex curing reaction. The viscosity of HPMA changes over time at simulated construction temperature, and the evolution of the chemical structure and rheological properties at different environmental temperatures at the early stage were systematically investigated in this work. After thorough exploration, the construction tolerance time for HPMA-50 % (with isocyanate pre-polymer content of 50 %) and HPMA-30 % (with isocyanate pre-polymer content of 30 %) at a construction temperature of 130 ℃ are 46 minutes and 72 minutes, respectively, which can basically meet the construction time requirements. The complex modulus of HPMA gradually increases with the increasing curing time, and the phase angle temperature dependence of HPMA-50 % is significantly weakened compared to HPMA-30 %, its viscoelasticity gradually transforms to thermoset. Meanwhile, the high-temperature rutting factor improvement rate of HPMA-50 % reaches 142.1 % after curing for 14 days, indicating a tremendously improved rutting resistance. The high-temperature creep recovery rates of HPMA-50 % and HPMA-30 % increased from 65.9 % and 3.6–96.1 % and 7.6 %, respectively, after 14 days of curing. This reveals that increasing the isocyanate pre-polymer content and extending the curing time all can significantly improve the entropy-elastic properties and creep recovery ability of HPMA. Fluorescence microscopy analysis showed that the polyurethane particles in HPMA changed from a granular structure to a network structure during the curing process, and gradually transitioned to a continuous phase as the pre-polymer content increased. Further research also revealed a good correlation between the conversion rate of isocyanates and the rheological performance index of HPMA. Additionally, a functional model between the rheological performance index of HPMA and curing times was successfully established, which accurately predicted the evolution law of the rheological performance of HPMA under different ambient temperatures. The evolution mechanism of the early performance of environmentally friendly HPMA was investigated in this work, which laid the methodological foundation and theoretical basis for determining the construction tolerance time of HPMA and accurately evaluating its performance at the early stage.

A Study on the Relationship between Phase Angle, Handgrip Strength, and Body Composition in Korean Adults: Based on the 1st Year Data of the 9th Korea National Health and Nutrition Examination Survey (2022)

A Study on the Relationship between Phase Angle, Handgrip Strength, and Body Composition in Korean Adults: Based on the 1st Year Data of the 9th Korea National Health and Nutrition Examination Survey (2022)

Bioelectrical phase angle in individuals after transcatheter aortic valve implantation.

Bioelectrical phase angle in individuals after transcatheter aortic valve implantation.

Hemoglobin and hematocrit levels are positively correlated with phase angle in mixed cancer patients: an exploratory cross-sectional study.

The aim of this study is to verify the correlationbetween hemoglobin (Hb) and hematocrit (Ht) levels with phase angle (PhA) values in patients with cancer of the gastrointestinal tract and accessory digestive organs. A cross-sectional study was conducted with 82 patients (38 females/44 males) diagnosed with cancer of gastrointestinal tract and accessory organs of digestion. Hb (g/dL) and Ht (%) levels were assessed by the cyanomethemoglobin and microhematocrit methods, respectively. Body composition and PhA were evaluated by the bioelectrical impedance analysis (BIA). The cut-off point used to classify patients with low PhA was set < 4°. Fifty-five (67%) of patients had PhA ≥ 4° values. We observed that body weight, BMI, fat mass, % weight loss, Ht, and Hb were higher in the PhA ≥ 4° group than in the PhA < 4° group. In the regression analysis, we found a positive association between PhA, Ht, and Hb without and after adjustment for sex, age, BMI, and type of treatment. In mixed cancer patients, there was a positive correlation between blood-red cell markers and PhA. This may be evidence that we can use of hematological parameters to suggest changes in PhA values during oncological treatment.

Analysis of Field of View for a Moon-Based Earth Observation Multispectral Camera.

A Moon-based Earth observation multispectral camera provides a unique perspective for observing large-scale Earth phenomena. This study focuses on the analysis of the field of view (FOV) for such a sensor. Unlike space-borne sensors, the analysis of the FOV for a Moon-based sensor takes into account not only Earth's maximum apparent diameter as seen from the lunar surface but also the Earth's and the solar trajectory in the lunar sky, as well as the pointing accuracy and pointing adjustment temporal intervals of the turntable. Three critical issues are analyzed: (1) The relationship between the Earth's apparent diameter and the Earth's phase angle is revealed. It is found that the Earth's maximum apparent diameter encompasses the Earth's full phase, suggesting the FOV should exceed this maximum. (2) Regardless of the location on the lunar surface, a sensor will suffer from solar intrusion every orbital period. Although the Earth's trajectory forms an envelope during an 18.6-year cycle, the FOV should not be excessively large. (3) To design a reasonable FOV, it is necessary to consider both the pointing accuracy and pointing adjustment temporal interval comprehensively. All these insights will guide future Moon-based Earth observation multispectral camera design.

Exploring the association between phase angle of bioimpedance at 50 kHz and cardiovascular risk

BackgroundCardiovascular diseases are characterized by chronic inflammation, leading to increased inflammatory markers that can cause cell damage and death. Phase angle has emerged as a marker of cellular health. It is considered a prognostic factor in various acute and chronic conditions. However, few studies have examined its association with cardiovascular disease risk measures. This study aims to investigate the relationship between phase angle, the general Framingham risk score, and the HEARTS cardiovascular risk score.MethodsThis cross-sectional study included a convenience sample of adult patients of 2 primary health care services. Phase angle was measured using multifrequency bioimpedance analysis at 50 kHz. The risk of cardiovascular events was calculated using the Framingham and HEARTS risk scores. Statistical analysis included generalized linear regression models, unadjusted and adjusted according to sex and age, to determine the association between scores, risk factors, and phase angle.ResultsThe study included 164 individuals with a mean age 52.2 (SD 17.9). According to the HEARTS score, low-risk patients had higher phase angle values than those with high or very high risk [ß = -0.57 (95% CI -0.95; -0.19), P = 0.003]. Framingham scores showed a trend toward significance for higher mean phase angle values in low-risk than high-risk patients [ß = -0.43 (95% CI -0.88 to 0.02), P = 0.06].ConclusionPhase angle values were lower in high and very high-risk patients than in low-risk patients, which shows that phase angle is a promising risk predictor for patients with cardiovascular diseases.

On the in-situ determination of the effective secondary electron emission coefficient in low pressure capacitively coupled radio frequency discharges based on the electrical asymmetry effect

Abstract We present a method for the in-situ determination of the effective secondary electron emission coefficient (SEEC, γ) in a capacitively coupled plasma (CCP) source based on the γ-dependence of the DC self-bias voltage that develops over the plasma due to the Electrical Asymmetry Effect (EAE). The EAE is established via the simultaneous application of two consecutive radio-frequency harmonics (with a varied phase angle) for the excitation of the discharge. Following the measurement of the DC self-bias voltage experimentally, Particle-in-Cell/Monte Carlo Collision (PIC/MCC) simulations coupled with a diffusion-reaction-radiation (DRR) code to compute the argon atomic excited level dynamics are conducted with a sequence of SEEC values. The actual γ for the given discharge operating conditions is found by searching for the best match between the experimental and computed values of the DC self-bias voltage. The γ ≈ 0.07 values obtained this way are in agreement with typical literature data for the working gas of argon and the electrode material of stainless steel in the CCP source. The method can be applied for a wider range of conditions, as well as for different electrode materials and gases to reveal the effective SEEC for various physical settings and discharge operating conditions.

Measurement Verification of a Developed Strategy of Inrush Current Reduction for a Non-Loaded Three-Phase Dy Transformer

This article presents the measurement verification of a novel strategy for inrush current reduction in an unloaded three-phase Dy transformer. The strategy combines appropriate pre-magnetization of transformer cores with an original control switching system using initial phase values of the supply voltage as control variables. Measurements were recorded for primary voltages and currents as well as secondary voltages during transient states at start-up under no-load conditions. Various inrush scenarios were examined across the full angular spectrum of initial phase angles, both polarities, and in regard to different pre-magnetization current values. A detailed analysis of the inrush currents was performed using proprietary automated software based on the recorded data. A comparative study with a nonlinear mathematical model of the transformer was also conducted. Additionally, key technical aspects of the designed system for implementing the proposed pre-magnetization strategy with controlled voltage energization are discussed.

Impact of high‐intensity ultrasound, cooling rate, and storage temperature on physical properties and oil binding capacity in fully hydrogenated palm‐kernel lipid matrices

AbstractThe ability of a fat crystal network to entrap liquid oil is known as oil binding capacity (OBC) and is an imperative property in semi‐solid fats for use in confectionary, bakery, and snack products. Understanding the factors that increase the OBC of fats is crucial for developing fat‐based foods that are more resistant to unwanted oil migration. In this study, fully hydrogenated palm‐kernel based (FHPKO) lipid matrices were crystallized under different processing conditions to generate samples with a wide range of physical properties and OBC. Three dilutions were created by combining FHPKO with soybean oil (SBO)—75% FHPKO (containing 25% SBO), 50% FHPKO (50% SBO), and 20% FHPKO (80% SBO) and were crystallized at 33, 30, and 22°C; respectively. All the samples were crystallized using fast (FCR; 4.6°C/min) and slow (SCR; 0.1°C/min) cooling rates, as well as with (w) and without (wo) high‐intensity ultrasound (HIU; 20 kHz). These processing conditions resulted in four different sets of samples—FCR wo HIU, FCR w HIU, SCR wo HIU, SCR w HIU. Immediately after processing, the sample's hardness, solid fat content (SFC), viscoelasticity (G′, G″, δ), microstructure, melting behavior (Tpeak, enthalpy), and OBC using a centrifuge method (labeled OBCc) were analyzed. Samples were then stored at 22 and 5°C for 48 h and the aforementioned properties were measured again as well as OBC using a filter paper method (labeled OBCp). Results show that both OBCc and OBCp were positively correlated with the sample's SFC (rs = 0.912, p &lt; 0.001; rs = 0.777, p &lt; 0.001), storage moduli (G′) (rs = 0.674, p &lt; 0.001; rs = 0.526, p = 0.017), hardness (rs = 0.793, p &lt; 0.001; rs = 0.812, p &lt; 0.001), enthalpy (rs = 0.842, p &lt; 0.001; rs = 0.812, p &lt; 0.001), and the number of crystals (rs = 0.655, p &lt; 0.001; rs = 0.728, p &lt; 0.001); respectively. While no correlation between OBCp and the sample's peak melting temperature and microstructure was recorded, a negative association between the sample's peak melting temperature (rs = −0.782, p &lt; 0.001), phase angle (δ) (rs = −0.801, p &lt; 0.001), and crystal diameter (rs = −0.470, p = 0.004) was documented for OBCc. These results suggest oil binding capacity of palm‐kernel based crystallized fats can be increased by formulating harder fats that are elastic, contain more crystals, and have higher SFC and enthalpy. Additionally, the FCR with HIU processing conditions was the most effective in increasing the OBC.

Phase-Angle-Encoded Snake Optimization Algorithm for K-Means Clustering

The rapid development of metaheuristic algorithms proves their advantages in optimization. Data clustering, as an optimization problem, faces challenges for high accuracy. The K-means algorithm is traditaaional but has low clustering accuracy. In this paper, the phase-angle-encoded snake optimization algorithm (θ-SO), based on mapping strategy, is proposed for data clustering. The disadvantages of traditional snake optimization include slow convergence speed and poor optimization accuracy. The improved θ-SO uses phase angles for boundary setting and enables efficient adjustments in the phase angle vector to accelerate convergence, while employing a Gaussian distribution strategy to enhance optimization accuracy. The optimization performance of θ-SO is evaluated by CEC2013 datasets and compared with other metaheuristic algorithms. Additionally, its clustering optimization capabilities are tested on Iris, Wine, Seeds, and CMC datasets, using the classification error rate and sum of intra-cluster distances. Experimental results show θ-SO surpasses other algorithms on over 2/3 of CEC2013 test functions, hitting a 90% high-performance mark across all clustering optimization tasks. The method proposed in this paper effectively addresses the issues of data clustering difficulty and low clustering accuracy.

Comparison of CIPA Nutritional Screening with GLIM Criteria for Malnutrition, Prognostic Evolution, and Association with Phase Angle in Hospitalized Patients.

Hospital malnutrition has high prevalence and is associated with worse clinical outcomes. The lack of standardized nutritional screening prompted the creation of the CIPA screening tool. Several studies have shown that the phase angle (PA) is associated with increased nutritional risk and worse clinical outcomes. The aim of this study was to establish the concordance between the CIPA and GLIM criteria and to assess their correlation with PA values and clinical outcomes. A cross-sectional single-center study was carried out, with a prospective six-month follow-up for the prognostic variables. On admission, the CIPA and GLIM criteria and bioimpedanciometry were assessed. A total of 510 inpatients were included; 36.5% had positive CIPA outcomes and 46.1% had positive GLIM outcomes. The correlation between the CIPA and GLIM criteria had a kappa index of 0.26, p < 0.01. Those with positive CIPA had a higher mortality risk (OR = 1.81) and longer mean length of stay (MLS) (OR = 1.45). The PA cut-off points were determined by sex and age for CIPA (men > 65 years: 4.75°, men ≤ 65 years: 5.75°, women > 65 years: 4.75°, and women ≤ 65 years: 5.45°) and GLIM (men > 65 years: 4.95°, men ≤ 65 years: 5.85°, women > 65 years: 4.75°, and women ≤ 65 years: 5.55°). These PA cut-off points were associated with worse clinical outcomes with CIPA (mortality OR = 4.2; MLS OR = 1.51; readmissions OR = 2.28) and GLIM (mortality OR = 2.97; MLS OR = 2.61; readmissions OR = 1.79). CIPA screening shows a low correlation with GLIM nutritional assessment. Positive CIPA and GLIM have lower PAs than negative and worse prognostic outcomes. The PA cut-off points associated with worse outcomes have been established.

Оценка нутритивного статуса и рисков его нарушения у детей с болезнью Крона: одномоментное исследование

Children with Crohn's disease (CD) are at high risk for developing nutritional deficiencies. According to studies in adult patients with CD, loss of lean and skeletal muscle mass and decreased bone mineral density (BMD) are unfavorable prognostic factors for the course of the disease; among children, the prevalence of these changes has not been sufficiently studied as yet. The purpose of this research was to study the frequency and correlation between disorders of body composition and decreased bone mineral density in children with CD. Materials and methods used: medical records of 163 aged 5 to 17 y/o with a confirmed CD diagnosis were assessed for the risk of nutritional deficiency using STRONGkids screening tool, anthropometric parameters, body composition with bioimpedance measurements as well as the disease activity index with PCDAI and endoscopic activity with SES-CD. BMD was assessed in 145 using densitometry. Results: depending on the degree of risk of malnutrition, children were divided into 2 groups as follows: G1 with high and G2 with moderate risks for malnutrition. G1 patients had significantly lower values of both anthropometric indices (Z-scores BMI/age, mid-upper arm circumference/age) and lean and skeletal muscle mass (p&lt;0.001) along with more severe course of CD according to PCDAI (p&lt;0.001). According to bioimpedansometry data, a significant increase in catabolic processes was found in G1 children as a decrease in Z-scores for both the phase angle (p&lt;0.001) and the active cell mass (p&lt;0.001). A decrease in BMD was detected in 9 (37%) of G1 and 26 (21.4%) of G2. A correlation was found between Z-scores lean body mass/age and BMD/age (p&lt;0.001, Rs=0.612). Among children with reduced BMD values, the indicators for BMI, lean, skeletal muscle and active cell mass according to bioimpedance measurements were significantly lower (p&lt;0.001). Conclusion: the data obtained during the study proposes high incidence of decreased bone mineral density along with pathological changes in body composition in children with CD. The use of STRONGkids tool to identify children at high risk of developing malnutrition, especially in the absence of the technical ability to conduct a detailed assessment of nutritional status with determination of body composition and BMD indicators, makes it possible to timely identify patients requiring individual nutritional support aiming to optimizing diets and, if necessary, prescribing addition of specialized food supplements.

Resonance Capacitance Selection Method for Minimizing Leakage Magnetic Fields and Achieving Zero Phase Angles in Wireless Power Transfer Systems

This study proposes a novel approach for selecting the resonance capacitance of wireless power transfer systems, aiming to achieve a zero phase angle (ZPA) while simultaneously minimizing the leakage magnetic field. The performance of the method is validated across two key topologies: series–series (S–S or SS) and the double-sided inductor–capacitor–capacitor (LCC, LCC–LCC) topologies. By minimizing the vector phasor sum of the coil currents, the proposed approach effectively mitigates magnetic field leakage. The method is further validated through mathematical derivations, simulations, and experimental tests. The results reveal that using the proposed method to select resonance capacitances reduces the leakage magnetic field by up to 35.2% in the SS topology and by 42.0% in the double-sided LCC topology. Furthermore, the method improves the ZPA by more than 20° in both cases. These outcomes affirm the effectiveness of the proposed resonance tuning approach.

Improving the nutritional evaluation in head neck cancer patients using bioelectrical impedance analysis: Not only the phase angle matters.

Malnutrition and sarcopenia are highly prevalent in patients with head neck cancer (HNC). An accurate early diagnosis is necessary for starting nutritional support, as both are clearly associated with clinical outcomes and mortality. We aimed to evaluate the applicability and accuracy of body composition analysis using electrical bioimpedance vectorial analysis (BIVA) for diagnosing malnutrition and sarcopenia in patients with HNC cancer undergoing systemic treatment with chemotherapy or radiotherapy. Cross-sectional, observational study that included 509 HNC patients. A comprehensive nutritional evaluation that included BIVA was performed. The prevalence of malnutrition was higher in patients that received treatment with chemotherapy (59.2% vs. 40.8%, P<0.001); increased mortality was observed in malnourished patients (33.3% vs. 20.1%; P<0.001); ECOG status (1-4) was also worse in malnourished patients (59.2% vs. 22.8% P<0.001). Body cell mass (BCM) and fat mass were the most significantly associated parameters with malnutrition [OR 0.88 (0.84-0.93) and 0.98 (0.95-1.01), respectively]; BCM and fat free mass index (FFMI) were associated with several aspects including (1) the patient-generated subjective global assessment [OR 0.93 (0.84-0.98) and 0.86 (0.76-0.97), respectively], (2) the presence of sarcopenia [OR 0.81 (0.76-0.87) and 0.78 (0.66-0.92), respectively]. A BCM index (BCMI)<7.8 in combination with other parameters including FFMI and BCM accurately predicted patients with malnutrition [accuracy 95% CI: 0.803 (0.763-0.839); kappa index: 0.486; AUC: 0.618 (P<0.01)]. A BCMI cutoff of 7.6 was enough for identifying males with malnutrition (P<0.001), while it should be combined with other parameters in females. Body composition parameters determined by BIVA accurately identify patients with HNC and malnutrition. Phase angle, but other parameters including BCMI, FFMI and BCM provide significant information about nutritional status in patients with HNC.

A Joint Estimation Method of Distribution Network Topology and Line Parameters Based on Power Flow Graph Convolutional Networks

Accurate identification of network topology and line parameters is essential for effective management of distribution systems. An innovative joint estimation method for distribution network topology and line parameters is presented, utilizing a power flow graph convolutional network (PFGCN). This approach addresses the limitations of traditional methods that rely on costly voltage phase angle measurements. The node correlation principle is applied to construct a node correlation matrix, and a minimum distance iteration algorithm is proposed to generate candidate topologies, which serve as graph inputs for the parameter estimation model. Based on the topological dependencies and convolutional properties of AC power flow equations, a PFGCN model is designed for line parameter estimation. Parameter refinement is achieved through an alternating iterative process of pseudo-trend calculation and neural network training. Training convergence and loss function values are used as feedback to filter and validate candidate topologies, enabling precise joint estimation of both topologies and parameters. The proposed method’s accuracy, transferability, and robustness are demonstrated through experiments on the IEEE-33 and modified IEEE-69 distribution systems. Multiple metrics, including MAPE, IAE, MAE, and R2, highlight the proposed method’s advantages over Adaptive Ridge Regression (ARR). In the C33 scenario, the proposed method achieves MAPEs of 4.6% for g and 5.7% for b, outperforming the ARR method with MAPEs of 7.1% and 7.9%, respectively. Similarly, in the IC69 scenario, the proposed method records MAPEs of 3.0% for g and 5.9% for b, surpassing the ARR method’s 5.1% and 8.3%.

Small fatigue crack behavior of CP-Ti in thin-walled cruciform specimens under biaxial loading

This study investigates the small fatigue crack propagation behavior of commercially pure titanium (CP-Ti) using thin-walled cruciform specimens under in-plane biaxial loading, considering the effects of biaxial ratio and phase angle. Increasing phase angle results in more secondary cracks merging with main cracks perpendicular to the rolling direction (RD) and transverse direction (TD), a phenomenon attributed to the rise in shear stress that accelerates main crack growth. Higher loading biaxiality or a lower phase angle leads to decreased crack propagation rates and increased biaxial fatigue life. Electron backscatter diffraction (EBSD) analysis reveals that when the maximum normal stress aligns with the RD, prismatic slip primarily governs crack propagation, thereby accelerating crack propagation rates. Conversely, alignment with the TD reduces prismatic slip activity and crack propagation rates. Under equi-biaxial loading, prismatic slip activity decreases further, and crack propagation is dominated by multiple slip and twinning, consequently resulting in the slowest propagation rates. Additionally, a higher proportion of prismatic slip under high phase angle also accelerates crack propagation. Finally, incorporating Findley equivalent stress into the Chapetti model, which considers the crack length-dependent threshold effect, a highly accurate biaxial small fatigue crack propagation rate model is proposed.