Dimensions Diameter Research Articles

Optimization of CuOx/Ga2O3 Heterojunction Diodes for High-Voltage Power Electronics.

This study optimizes the CuOx/Ga2O3 heterojunction diodes (HJDs) by tailoring the structural parameters of CuOx layers. The hole concentration in the sputtered CuOx was precisely controlled by adjusting the Ar/O2 gas ratio. Experimental investigations and TCAD simulations were employed to systematically evaluate the impact of the CuOx layer dimension and hole concentration on the electrical performance of HJDs. The results indicate that increasing the diameter dimension of the CuOx layer or tuning the hole concentration to optimal values significantly enhances the breakdown voltage (VB) of single-layer HJDs by mitigating the electric field crowing effects. Additionally, a double-layer CuOx structure (p+ CuOx/p- CuOx) was designed and optimized to achieve an ideal balance between the VB and specific on-resistance (Ron,sp). This double-layer HJD demonstrated a high VB of 2780 V and a low Ron,sp of 6.46 mΩ·cm2, further yielding a power figure of merit of 1.2 GW/cm2. These findings present a promising strategy for advancing the performance of Ga2O3 devices in power electronics applications.

ТЕХНІЧНЕ РІШЕННЯ ДЛЯ ПРОЄКТУВАННЯ СПРЯЖЕНИХ ЗУБЧАСТИХ ЗАЧЕПЛЕНЬ ЩОДО ВИЗНАЧЕННЯ ІНТЕРФЕРЕНЦІЇ В ОЗБРОЄННІ ТА ВІЙСЬКОВІЙ ТЕХНІЦІ

In the complex realities of the modern industry of Ukraine, an important direction of scientific and technical development is the optimization of technical solutions in the design of coupled gears of kinematic pairs regarding the determination of interference in weapons and military equipment with increased requirements for the degree of complexity of the designed products and shortening the terms of order fulfillment. Given the serious pressure of crisis phenomena in the economy and increased competition on the market, these components force us to carry out work at the most modern technical level. The paper proposes the optimization of the analytical technical solution for designing the contact line between the axes of the coupled gear engagements of kinematic pairs to determine the interference. This will make it possible to reduce the equation to a parametric form, to algorithmize and optimize the modeling of the product, and to design the contact surface of the gear when designing products in weapons and military equipment. The technical solution to the given problem refers to gear-coupled mechanisms of external engagement, the shape of the teeth of the wheels is formed by wrapping the initial contour of the gear rack, and the number of teeth is determined depending on the purpose of the mechanism, the required gear ratio and diametrical dimensions. Such mechanisms are used in various units and units of weapons and military equipment, namely in the form of gear wheels of reducers, winches, planetary and wave gears and as working bodies of pumps, hydraulic motors, compressors and internal combustion engines with straight and helical teeth. To avoid interference at the design stage, it is necessary to analyze the technical curvilinear characteristics of the conjugated surfaces. The application of technical solutions for the description of real surfaces obtained as a result of the creation of a curvilinear model reflects the real physical process of determining interference.

Can a Light Detection and Ranging (LiDAR) and Multispectral Sensor Discriminate Canopy Structure Changes Due to Pruning in Olive Growing? A Field Experimentation.

The present research aimed to evaluate whether two sensors, optical and laser, could highlight the change in olive trees' canopy structure due to pruning. Therefore, two proximal sensors were mounted on a ground vehicle (Kubota B2420 tractor): a multispectral sensor (OptRx ACS 430 AgLeader) and a 2D LiDAR sensor (Sick TIM 561). The multispectral sensor was used to evaluate the potential effect of biomass variability before pruning on sensor response. The 2D LiDAR was used to assess its ability to discriminate volume before and after pruning. Data were collected in a traditional olive grove located in Tenute di Cesa Farm, in the east of Tuscany, Italy, characterized by a 4x6 m planting layout and by developed plants. LiDAR data were used to measure canopy volumes, height, and diameter, and the generated point cloud was studied to assess the difference in density between treatments. Ten plants were selected for the study. To validate the LiDAR results, manual measurements of the canopy height and diameter dimensions of the plants were taken. The pruning weights of the monitored plants were obtained to assess the correlation with the canopy characterization data. The results obtained showed that pruning did not affect the results of the multispectral sensor, and the potential variation in canopy density and porosity did not lead to different results with this instrument. Plant volumes, height, and diameters calculated with the LiDAR sensor correlated well with the values of manual measurements, while volume differences between before and after pruning obtained good correlations with pruning weights (Pearson correlation coefficient: 0.66-0.83). The study of point cloud density in canopy thickness and height showed different shapes before and after pruning, especially in the former case. Correlations between point cloud density obtained from LiDAR and multispectral sensor results were not statistically significant. Even if more studies are necessary, the results obtained can be of interest in pruning management.

Correlating microscopic pore characteristics with permeability coefficient in porous asphalt concrete: an X-ray CT-based approach

The internal void structure of porous asphalt concrete (PAC) is crucial for its drainage performance. This study employs X-ray CT scanning and image processing techniques to analyze key microscopic parameters of PAC, including void porosity, number of voids, equivalent diameter, and fractal dimension. The evolution of these parameters under clogging and cleaning conditions is investigated. A predictive model for the permeability coefficient of PAC is established based on the findings. Results indicate that internal void distribution exhibits similar variations across specimens with different void porosities during clogging and cleaning. Notably, the number of voids increases significantly after clogging, while equivalent diameter decreases and fractal dimension remains stable. All parameters are effectively restored post-cleaning. A strong correlation exists between void porosity, number of voids, equivalent diameter, fractal dimension, and the permeability coefficient, ranked from best to worst as: void porosity, number of voids, equivalent diameter, and fractal dimension, with a correlation coefficient of 0.991 for the predictive model.

Specific Morphology of Coronary Artery Aneurysms in Mainly White Patients With Kawasaki Disease: Initial Data From the Cardiac Catheterization in Kawasaki Disease Registry.

Patients with Kawasaki disease (KD) with coronary artery involvement require long-term cardiac care. Although respective evidence-based recommendations are missing, cardiac catheterization is still considered the gold standard for diagnosing detailed coronary pathology. Therefore, to better understand coronary artery pathology development, we conducted a survey to document and evaluate cardiac catheterization data in a European population. We retrospectively analyzed cardiac catheterization data from KD children from the year 2010 until April 2023. This registry covers basic acute-phase clinical data, and more importantly, detailed information on morphology, distribution, and the development of coronary artery pathologies. A total of 164 mainly White patients (65% boys) were included. A relevant number of patients had no coronary artery aneurysm (CAA) at the cardiac catheterization, indicating that distal CAAs were almost exclusively detected alongside proximal CAAs. Patients with multiple CAAs revealed a significant positive correlation between the number of CAAs and their dimensions in diameter and in length. Location of the CAA within the coronary artery, age at onset of KD, or natal sex did not significantly influence CAA diameters, but CAAs were longer in older children and in boys. That distal CAAs were only present together with proximal ones will hopefully reduce diagnostic CCs in patients with KD without echocardiographically detected proximal CAAs. Furthermore, this study gives valuable insights into dimensional specifics of CAAs in patients with KD. As an ongoing registry, future analyses will further explore long-term outcomes and performed treatments, helping to refine clinical long-term strategies for patients with KD. URL: https://drks.de/; Unique Identifier: DRKS00031022.

Effect of Growth Regulators and Nano Materials to Cope with Salinity on Anatomical Characteristics of Pea Plant

Abiotic stresses, particularly salinity, severely hinder crop productivity by disrupting physiological processes and reducing yields. Pea (Pisum sativum L.), a vital crop, is highly sensitive to salinity, making it crucial to explore strategies that enhance its tolerance to such stresses. This study investigates the effects of Ascorbic Acid (AsA), 5-Aminolevulinic Acid (ALA), and Nano-Selenium (N-Se) on the anatomical characteristics of pea plants subjected to severe salinity stress (120 mM NaCl). Transverse sections of the fourth internode and leaf blade were analyzed, focusing on stem and leaf structure. The results showed that foliar application of AsA (100 ppm) significantly improved anatomical traits, such as stem diameter, cortex thickness, and vascular bundle dimensions, compared to the control and other treatments. ALA (50 ppm) also improved anatomical features, albeit to a lesser extent, while N-Se (20 ppm) exhibited the lowest enhancement. Leaf tissue analysis revealed that AsA improved leaflet structure, increasing epidermis thickness and vascular bundle dimensions under salinity stress. The application of AsA, ALA, and N-Se mitigated the negative effects of salinity, likely due to their roles in enhancing stress tolerance, reducing oxidative damage, and improving nutrient uptake. This study highlights the potential of these bio-stimulants to improve the anatomical resilience of pea plants under salinity stress, contributing to better crop performance in saline environments.

Variability in soil characteristics in the field–bund transition area increases water loss potential in paddy fields

Water loss in paddy fields occurs through various pathways, and previous studies have primarily focused on water seepage in the field, often overlooking the potential for the field-bund area. In this study, 3 typical paddy fields in the plain river network area of southeastern China were selected to clarify the differences in the soil structure and hydraulic characteristics at different positions within the field–bund area: the field, inner bund, middle bund and outer bund. The interactions between basic soil properties and hydraulic characteristics were also evaluated. The results revealed that the outer bund presented the lowest soil porosity (6.92 %), followed by the field (7.52 %), middle bund (7.77 %), and inner bund (8.09 %). The soil pores in the field presented the smallest mean diameter and fractal dimension and the highest degree of anisotropy. The deep layer of the bund contained more macropores, and the soil pores exhibited greater spatial distribution heterogeneity. The bottom layer in the field and bund presented the lowest average Ks value of only 0.05 mm min−1, indicating the presence of a plow pan and a notable tendency for lateral seepage. Differences in the soil structure and hydraulic parameters between the field and bund created a driving force for lateral seepage and rendered the field–bund area a hotspot for water loss. For the analysis of the underlying water loss mechanism, the structural equation model represented 65 % of the total variance in the hydraulic parameters. The micropore characteristics had the greatest positive direct effect on the hydraulic parameters, with a standardized path coefficient of 0.39 (p < 0.001). The soil physical properties were not directly related to the hydraulic parameters but exerted an indirect effect through aggregate stability and micropore and macropore characteristics, with a total indirect standardized path coefficient of −0.41.

Numerical studies on structure optimization and flow characteristics of a hydrogen recirculation ejector under multiple load conditions

Ejectors are ideal hydrogen recirculation devices for PEMFC systems but typically exhibit poor recirculation performance at low loads. For purpose of extending ejector's operating range in vehicular applications, the entraining performance across multiple loads should be focused. In this study, A 40 kW ejector was designed with a 1D theory and optimized using a 2D CFD model. Simulations were conducted to study the influence of various diameter and axial dimensions on the ejector's performance and flow characteristics. The results reveal that as the load increases from 20% to 100%, the suboptimal diffuser exit diameter decreases from 2.5 to 1.5 times the mixing chamber diameter, the optimal nozzle exit position increases from 0.59 to 0.63 times, and the optimal mixing chamber length increases from 2.2 to 4.3 times. A convergent nozzle with a short throat significantly improves low-load entraining performance and achieves the highest performance growth in the variable-nozzle design. Additionally, an optimization method for axial dimensions based on the proposed parameter flow uniformity was established, allowing for precise determination of the optimal dimensions through a few simulations.

Myocardial work in idiopathic premature ventricular contractions: Assessing left ventricular function and prognosis.

Premature ventricular contractions (PVCs) can lead to impairment of left ventricular function. The noninvasive myocardial work technique, which incorporates left ventricular afterload, represents a new method for assessing left ventricular functional. The aim of this study is to explore the value of noninvasive myocardial work technique in assessing left ventricular systolic function in patients with PVCs. Compare the clinical data, two-dimensional echocardiography parameters, and myocardial work parameters of 66 patients with PVCs and 35 healthy volunteers and explore the relevant risk factors for postoperative recurrence in patients with PVCs. In patients with PVCs compared to the control group, they exhibit enlargement of left atrial diameter (LAD) and left ventricular internal dimension in diastole (LVIDd), as well as thickening of the left ventricular wall. The global work waste (GWW) increases, while the global work efficiency (GWE) decreases. There is a significant negative correlation between the PVC burden and GWE (r = -0.70, p <0.01), and a significant positive correlation between the PVC burden and GWW (r = 0.58, p <0.01). GWE is a sensitive indicator for predicting the recurrence of PVCs after radiofrequency ablation. Patients with GWE <91.5%, global longitudinal strain (GLS) <15.5%, and ejection fraction (EF) <62.5% have a higher postoperative recurrence rate. PVCs can cause impairment of left ventricular systolic function. GWE is the most sensitive indicator for predicting postoperative recurrence in patients with PVCs. Patients with GWE <91.5%, GLS <15.5%, and EF <62.5% have a higher postoperative recurrence rate.

Fatigue and Autofrettage Analysis of Steel Sleeve Based on Precision Fit under Ultra High Pressure

Abstract In order to ensure precision fit between steel sleeve and plunger, copper sleeve and the other parts of the ultra high pressure plunger pump, as well as increase the fatigue life of steel sleeve, this paper made the analysis of work process and fatigue life of ultra high pressure autofrettage steel sleeve of plunger pump based on both analytical method and FEM. The elastic-plastic boundary radius, radial stress and plastic zone displacement were obtained based on the elastic-plastic mechanics analysis of ultra high pressure steel sleeve. The functional relationship built related to precision fit among autofrettage pressure, inner diameter expectation and displacement could ensure the machining dimension of inner diameter of steel sleeve and realize the precise control of inner diameter of steel sleeve. The analytical method and FEM for calculating fatigue life was also proposed, which are verified by experiment. The research shows that machining dimension is determined by inner diameter expectation in the autofrettage process to ensure precision fit; autofrettage treatment can reduce the working stress level of the steel sleeve and extend the fatigue life remarkably. These conclusions contribute to guide the design of steel sleeve.

Korištenje morfoloških značajki sadnica obične bukve (Fagus sylvatica L.) za selekciju reprodukcijskog materijala iz provenijencija vjerojatno zahvaćenih klimatskim promjenama

Global climate change causes the reduction of tree growth and spread of European beech (Fagus sylvatica L.) forests, thus indicating the need to preserve tree abundance due to the changes that have occurred. The comparison of beech seedlings from various provenances in southeast and central Europe was carried out based on the dimensions of root collar diameter and height to select the proper starting material that would reduce the negative consequences of the climate. There have been statistically significant differences in root collar diameter and height between various seedlings tested in European provenances. Clear differentiation was recorded between European countries in the growth performances of one-year-old and two-year-old seedlings of F. sylvatica based on the nursery test. The study's results indicate the potential for producing adaptable beech reproductive material from various European provenances. This finding lays the groundwork for future precise analyses that aim to select provenances tolerant to changing climate conditions.

Vericiguat on C-reactive Protein Level and Prognosis in Patients with Hypertensive Heart Failure.

Hypertensive heart failure (HHF) has a high incidence and poor prognosis. This article evaluated the efficacy and safety of Vericiguat in HHF and analyzed the relationship between C-reactive protein (CRP) levels and patient prognosis. 110 HHF patients were divided into Placebo and Vericiguat groups. Cardiac function was assessed by echocardiography and 6-minute walk test (6MWT). Blood samples were collected to detect the levels of N-terminal pro-brain natriuretic peptide (NT-proBNP), cardiac troponin I (cTnI), endothelin (ET-1), nitric oxide (NO), and CRP. Left ventricular end systolic diameter (LVESD) and left ventricular end diastolic dimension (LVEDD) were reduced, the left ventricular ejection fraction (LVEF) and 6MWT were increased, and the serum levels of NT-proBNP, cTnI, ET-1, NO, and CRP were decreased in Vericiguat group as against Placebo group; The total effective rate was 76.4% in Placebo group and 92.7% in Vericiguat group (P < 0.05). The adverse reaction rate was 10.9% and 9.1% (P > 0.05). The proportion of persons with poor prognosis and no improvement of cardiac function in patients with highly expressed CRP before treatment was higher as against patients with low expression of CRP (P < 0.05). Highly expressed CRP is an independent risk factor for poor prognosis. Vericiguat is safe and effective in improving cardiac function in HHF patients.

Island Flap Rotation Technique as a Novel Repair Surgery Method for Severe Degenerative Mitral Valve Regurgitation

Background: The current study was done to assess the efficacy and safety of the island flap rotation technique as a novel method for severe mitral valve regurgitation. Methods: Twenty-three patients were selected to undergo mitral valve repair with the island flap rotational technique. It takes the principle of doing quadrangular resection of the P2 leaflet and flipping the dissected area so that the ruptured primary chordae are replaced with the secondary or tertiary chordae. Transesophageal echocardiography parameters were evaluated before surgery and 1 week after surgery, just prior to discharge. Results: The procedure was done successfully with 100% mitral regurgitation reduction to ≤1+ along with significantly reduced left ventricular end-diastolic diameter (p = 0.001) and left atrial dimension (p = 0.000). The left ventricular ejection fraction was significantly reduced after the procedure (p = 0.000). Older age significantly affects the presence of residual mitral regurgitation (p = 0.02). No thromboembolic adverse events and mortality were observed during the 3-month follow-up. Conclusions: The use of island flap rotation technique as a novel method for severe mitral regurgitation with P2 lesions has been proven to be effective and safe with preserving the valve tissue.

Substrate-Integrated Cylindrical Cavity Controlled Hexa-Polarization Flexible Cylindrical Dielectric Resonator Antenna for Ku-Band Applications

A substrate-integrated cylindrical cavity (SICC) fed polarization flexible cylindrical dielectric resonator antenna (CDRA) is presented in this literature. To excite the CDRA, a unique and simple feeding approach based on substrate-integrated waveguide (SIW) technology is demonstrated. This SICC is fed by two 50Ω microstrip lines, oriented orthogonally to each other. The SICC with a cross slot on its top metalized surface and the TM110 mode excites inside it act together to couple energy efficiently to the CDRA. Applying different phase combinations signals at the two input ports of the SICC, the CDRA can radiate in four different orientations linear polarization (LP) (along φ = 0°, 45°, −45°, and 90° ), left-handed circular polarization (LHCP), and right-handed circular polarization (RHCP). A conventional cylindrical dielectric resonator having relative permittivity ϵd = 10 is preferred. Its diameter, height, and cross-slot dimensions are optimized to operate the CDRA over Ku-band with 12% impedance bandwidth, 2-dB axial ratio (AR) bandwidth of 11%, and 3-dB gain bandwidth of 12%. In this operating band, CDRA resonates at three different higher-order modes (HEM32δ, HEM113, and HEM12δ+2) with 8 ± 1.6 dBi/dBic gain for all the polarization states. The measurements of this antenna are conducted using two external phase shifters and one power divider.

Aortic valve cusp size and shape in dilated trileaflet aortic roots

ObjectivesThe objective of the study was to quantify the differences in cusp size and shape in patients with normal and dilated trileaflet aortic roots and in dilated roots with or without aortic regurgitation. MethodsA retrospective analysis of computed tomography studies in patients with normal and dilated trileaflet aortic roots was performed measuring root and cusp dimensions. Normal root size was defined as sinuses of Valsalva diameter less than 40 mm, dilated as 45 mm or greater. Root measurements normalized to basal ring diameter and cusp measurements normalized to geometric height were analyzed to assess the shape. Additionally, comparison of dilated roots with or without aortic regurgitation was made. ResultsWe analyzed 146 normal and 104 dilated aortic roots and 73 propensity-matched pairs. Dilated roots were larger in all dimensions and had increased ratio between commissural and basal ring diameter (1.58 ± 0.23 vs 1.11 ± 0.10, P < .001). Cusps in dilated roots were larger in all measured dimensions and were elongated with increased normalized cusp insertion length (3.64 ± 0.39 vs 3.26 ± 0.20, P < .001) and normalized free margin length (2.53 ± 0.30 vs 2.16 ± 0.19, P < .001). In patients with dilated root and no cusp prolapse (n = 83), those with moderate or severe aortic regurgitation had larger commissural diameter but similar cusp dimensions compared with those with no or mild aortic regurgitation. ConclusionsThe cusps in dilated roots elongate transversely and to a lesser degree radially. Functional aortic regurgitation is caused by extensive commissural dilatation and not by inadequate cusp adaptation.

Effect of gradation on macro-meso shear properties of the alluvial-diluvial soil-rock mixture (ADSRM)

Alluvial-diluvial soil-rock mixture (ADSRM) is a unique geological material primarily consisting of pebbles, gravel, and soil. Gradation design significantly enhances the shear strength of ADSRM, offering significant implications for sustainable construction of transportation infrastructure in mountainous regions. Hence, the N-method of gradation theory was employed for the gradation design of ADSRM fillers in this study. Macro-mechanical testing reveals that the graded sample exhibits significantly higher shear strength, equivalent cohesion, and friction angle compared to the ungraded sample, with more pronounced shear dilatancy. Meso-shear properties suggest that the graded sample has a lower percentage of pore area compared to the ungraded sample, but a higher percentage of small pores relative to total pores, and more crushed rock blocks under the same normal stress conditions. Pore abundance indicates that the majority of pores on the shear plane are oblate in shape. The findings from the equivalent diameter and fractal dimension of the rock block contour suggest improved grinding roundness of rock blocks in the graded sample post-shearing. In summary, the quantity of pores and broken rock blocks primarily impacts the strength and equivalent cohesion of the filler, while the abundance, roundness, shape coefficient, and fractal dimension of rock block contour mainly affects the internal friction angle.

Predicting incomplete occlusion of intracranial aneurysms treated with flow diverters using machine learning models.

Intracranial saccular aneurysms are vascular malformations responsible for 80% of nontraumatic brain hemorrhage. Recently, flow diverters have been used as a less invasive therapeutic alternative for surgery. However, they fail to achieve complete occlusion after 6 months in 25% of cases. In this study, the authors built a tool, using machine learning (ML), to predict the aneurysm occlusion outcome 6 months after treatment with flow diverters. A total of 667 aneurysms in 616 patients treated with the Pipeline embolization device at a tertiary referral center between January 2011 and December 2017 were included. To build the predictive tool, two experiments were conducted. In the first experiment, six ML algorithms (support vector machine [SVM], decision tree, random forest [RF], k-nearest neighbor, XGBoost, and CatBoost) were trained using 26 features related to patient risk factors and aneurysm morphological characteristics, and the results were compared with logistic regression (LR) modeling. In the second experiment, the models were trained using the top 10 features extracted by Shapley additive explanation (SHAP) analysis performed on the RF model. The results showed that the authors' tool can better predict the occlusion outcome than LR (accuracy of 89% for the SVM model vs 62% for the LR model), even when trained using a subset of the features (83% accuracy). SHAP analysis revealed that age, hypertension, smoking status, branch vessel involvement, aneurysm neck, and larger diameter dimensions were among the most important features contributing to accurate predictions. In this study, an ML-based tool was developed that successfully predicts outcome in intracranial aneurysms treated with flow diversion, thus helping neurosurgeons to practice a more refined approach and patient-tailored medicine.

A multi-gradient analysis of microscopic void characteristics' influence on the mechanical properties of open-graded friction course bituminous pavement

The mechanical properties of the open-graded friction course (OGFC) bituminous pavement are tied to its microscopic void structure, but multiple void parameters influence void formation and distribution. Solely using air voids as an indicator of pavement stability is challenging. Thus, a multi-gradient analysis of void structure factors is vital for advancing OGFC pavement's mechanical property research. This study used computerized tomography (CT) and digital image processing (DIP) to gather data on void structure distribution, size, and complexity in OGFC bituminous mixtures. Mechanical experiments assessed high-temperature deformation, low-temperature cracking, and water damage resistance. Analysis of void parameters' influence led to a predictive model for mechanical property in OGFC mixtures. The study found that as air voids increase within the 18 %–24 % range, both equivalent void diameter and void fractal dimension increase, while void count decreases. Conversely, coarser gradation and a larger nominal maximum aggregate size (NMAS) lead to increased equivalent void diameter but decreased void fractal dimension, reducing void complexity. The mechanical properties of OGFC mixtures decline with rising air voids but improve with coarser gradation and larger NMAS. The predictive model highlights the void fractal dimension and NMAS as critical indicators, with other factors showing weaker influence or multicollinearity issues that are unfit for model fitting. The findings could provide useful references for the structural design, property evaluation, and quality control of OGFC bituminous pavements in actual road construction.

Discriminating Glioblastoma from Normal Brain Tissue In Vivo Using Optical Coherence Tomography and Angiography: A Texture and Microvascular Analysis Approach

Brain tumors arise from abnormal cell growth in the brain. Glioblastoma, the most common and aggressive type, poses significant challenges for identification during surgery. The primary goal of this study is to identify and differentiate normal brain tissue from glioblastoma tissue using optical coherence tomography (OCT) and OCT angiography (OCTA). These techniques offer a non-invasive way to analyze the morphological and microvascular alternations associated with glioblastoma in an animal model. To monitor the changes in morphology and vascular distribution of brain tissue as glioblastoma tumors grow, time-series OCT and OCTA results were collected for comparison. Texture analysis of OCT images was proposed using the gray-level co-occurrence matrix (GLCM), from which homogeneity and variance were calculated as discriminative parameters. Additionally, OCTA was used to assess microvascular characteristics, including vessel diameter, density, and fractal dimension. The findings demonstrate that the proposed methods can effectively distinguish between normal and cancerous brain tissue in vivo.

Modeling of flexible shaft for robotics applications

Reducing moving mass and effective inertia is essential for achieving safe human–robot collaboration. This can be achieved either by employing remote actuation, which moves the mass of actuators away from the moving elements of the robot, or by elastic actuation, which decouples the inertia of the actuator from the inertia of the robot’s link. Flexible shafts, being torsionally compliant slender long shafts, offer a combination of remote and series elastic actuation over an obstacle. Modeling such transmission is complicated due to its three-dimensional deformation in torsion, bending, and helical buckling. This paper proposes an algorithm for estimating the polar moment of inertia and stiffness of the flexible shafts using their physical dimensions of length and diameter. Using an inertia-spring–damper model, the stiffness parameters are estimated experimentally for nine flexible shafts with variable diameters and lengths in straight and bent configurations. The proposed algorithm is validated with experimental stiffness values for variable diameters and lengths in straight configuration. For bent configuration, an empirical formulation is provided to incorporate the bending deformation effect till a bending angle of 45∘.