Device Size Research Articles

Engineering mechanical resonances of magnetoelectric transducers

Magnetoelectric transducers are being investigated as a promising alternative for wireless power transfer in cases where small device size and/or low operation frequency are desired. To maximize the output power of such transducers, operation at their mechanical resonance frequency is imperative. However, a reduction in size along the direction of oscillation is intrinsically accompanied by an increase in resonance frequency. Here, we report on a computational shape optimization strategy to minimize the resonance frequency in magnetoelectric transducers by ≈38% within a set of given optimization constraints. We show that our algorithm can be used to guide the design of magnetoelectric transducers optimized to operate at different resonance frequencies and allows for consistent frequency spacing between transducers, thus enabling separately addressable devices and clustered operation. Finally, we propose four needle-shaped devices that could be used as bioimplants that impose minimal tissue damage upon direct insertion into tissue. The increase in resonance frequency associated with the needle shape is overcompensated by a frequency minimization step. Our work paves the way for computationally guided resonance frequency tuning in the field of magnetoelectric transducers.

Flexible Optical Fiber Sensor for Non-Invasive Continuous Monitoring of Human Physiological Signals.

With increasing health awareness, monitoring human physiological signals for health status and disease prevention has become crucial. Non-invasive flexible wearable devices address issues like invasiveness, inconvenience, size, and continuous monitoring challenges in traditional devices. Among flexible sensors, optical fiber sensors (OFSs) stand out due to their excellent biocompatibility, anti-electromagnetic interference capabilities, and ability to monitor multiple signals simultaneously. This paper reviews the application of flexible optical fiber sensing technology (OFST) in monitoring human lung function, cardiovascular function, body parameters, motor function, and various physiological signals. It emphasizes the importance of continuous monitoring in personal health management, clinical settings, sports training, and emergency response. The review discusses challenges in OFST for continuous health signal monitoring and envisions its significant potential for future development. This technology underscores the importance of constant health signal monitoring and highlights the advantages and prospects of optical fiber sensing. Innovations in OFS for non-invasive continuous monitoring of physiological signals hold profound implications for materials science, sensing technology, andbiomedicine.

Computational evaluation of interactive dynamics for a full transcatheter aortic valve device in a patient-specific aortic root.

Transcatheter aortic valve implantation (TAVI) has become a key treatment for severe aortic stenosis, especially for patients unsuitable for surgery. Since its introduction in 2002, TAVI has advanced significantly due to improvements in imaging, operator skills, and device engineering. Despite these innovations, challenges in device sizing and positioning remain, complicating outcome predictions. Computational modelling is a powerful tool to aid TAVI device design and to understand its interactive behaviour with the aortic root during the deployment. Previous studies often simplified tissue properties, neglected patient-specific geometries or omitted crucial elements such as leaflets and fabric. This paper presents a numerical framework capable of simulating the whole crimping and deployment process of a full TAVI device in a patient-specific aortic root including the native leaflets and calcifications. We conduct a comprehensive investigation into the mechanical behaviour of the TAVI and its interactions with patient-specific aortic root through dynamic finite element analysis during the deployment process, with validation against experimental results. Additionally, we examined the influence of applied pressure during balloon inflation on the interactive dynamics of the entire model. The study concludes that selecting optimal balloon pressures is crucial for enhancing TAVI device performance and reducing complications. Numerical simulations demonstrate that appropriate balloon pressure ensures sufficient flow area and effective contact pressure between the TAVI and the aortic root, while minimising deformation and the risk of paravalvular leak.

High Reynolds number bulk effects induced by superhydrophobic surfaces

Drag reduction induced by superhydrophobic surfaces made of streamwise grooves is investigated through direct numerical simulation of turbulent pipe flow. When the ratio between the groove width and the viscous length exceeds 50, most of the wall slippage effect is maintained in the bulk of the flow; thus, a large drag reduction is achieved. The effect is explained in terms of a modified mean and turbulent kinetic energy balance that accounts for the slippage effect at the wall. With typical groove sizes of technological devices, values of order 50 wall units can be achieved only at high friction Reynolds number, here increased up to Reτ≃2300.

Compact and broadband polarization splitter-rotator on thin-film lithium niobate minimized with the fast quasi-adiabatic algorithm.

Polarization splitter-rotators (PSRs) are crucial for on-chip polarization-division multiplexing (PDM) systems. Here, we design and experimentally demonstrate a compact and broadband PSR based on adiabatic mode evolution on a thin-film lithium niobate (TFLN) platform. A novel, to the best of our knowledge, quasi-adiabatic algorithm is proposed to minimize the device size. The fabricated PSR, with an adiabatic waveguide length of only 0.4 mm, exhibits an insertion loss of <0.64 dB and a polarization extinction ratio of >20 dB over a 122-nm bandwidth.

Multi-objective optimization and posteriori multi-criteria decision making on an integrative solid oxide fuel cell cooling, heating and power system with semi-empirical model-driven co-simulation

An integrative solid oxide fuel cell combined cooling, heating and power system in green buildings with hydrogen energy of byproduct water enables carbon neutrality transformation. However, underlying mechanisms on capacity sizing of combined cooling, heating and power system devices and its impacts on system techno-economy have not been figured out especially considering dynamic degradation and efficiency of associated devices. In this study, a multi-software optimization platform is established by MATLAB-TRNSYS co-simulation for sizing parametrical analysis, with well balance of modelling complexity and computational efficiency. A self-sufficient combined cooling, heating and power system is modelled integrating with a semi-empirical surrogate model of solid oxide fuel cell to interact with other balance of plant types efficiently. Total energy efficiency and annual total cost are optimized through parametrical analysis on device size of each component (battery, electrolyzer and solid oxide fuel cell) and analysis of variance for contribution ratio quantification. Results indicate that, the size increase in electrolyzer and solid oxide fuel cell will improve system total energy efficiency by 13.635 % and 2.194 %, but promote annual total cost by 4.042 × 104 $ and 2.389 × 103 $, respectively. Besides, sensitivity analysis indicates that the electrolyzer size prioritizes other design parameters in techno-economic performance. Optimal sizes of battery, electrolyzer and solid oxide fuel cell are in cell number range of 333 – 403, 17 – 20, and 26 – 30, respectively, with corresponding optimal total energy efficiency and annual total cost at 70.861 % – 72.147 % and 6.723 × 104 $ – 7.325 × 104 $, respectively. The research results can provide guidance on hydrogen-based cooling, heating and power system design and operation with techno-economic feasibility for low-carbon district energy transition.

A comparison of MRI and intraoperative measurements to determine interspinous spacer device size.

To determine whether preoperative magnetic resonance imaging (MRI) can reliably determine intraoperative measurements in the Vertiflex Interspinous Spacer (ISS) procedure. Patients who underwent Vertiflex ISS with Lumbar Spinal Stenosis (LSS) and a preoperative MRI available in picture archiving and communication system (PACS) between January 2013 to February 2023 were identified retrospectively from the University of Chicago Medical Center Database. An experienced board-certified pain specialist and well-trained 2nd-year medical student independently performed measurements of the interspinous space where Vertiflex ISSs of various sizes are inserted. MRI measurements were taken blinded to intraoperative measurement and ISS implant size used in the procedure. Pearson's correlation, paired T-test, intraclass correlation coefficients (ICC), absolute agreement, and 2-way random effects model were used to determine the relationships between MRI, intraoperative measurement, and ISS size. A total of 79 patients who underwent the Vertiflex ISS procedure were included in the study. Median Vertiflex ISS size was 10 mm (10-12), mean intraoperative measurement was 11.40 mm (±1.23), and mean MRI measurement was 11.24 mm (±1.44). Mean differences were not significant in intraoperative and MRI measurements (p = 0.271). Pearson's correlation between ISS size and intraoperative measurement was 0.807 (p < 0.001), representing the current best practice model. Pearson's correlation was 0.668 (p < 0.001) between MRI measurement and ISS size and 0.542 (p < 0.001) between MRI and intraoperative measurement. ICC showed good agreement and moderate reliability (0.698) between intraoperative and MRI measurements. Observer interrater ICC agreement of the MRI interspinous space measurement was 0.95 (p < 0.001). Measuring interspinous space on MRI yielded, on average, a value smaller than the intraoperative measurement in Vertiflex ISS procedures, but the mean differences were not significant. Good agreement and moderate reliability were found between observer MRI and surgeon intraoperative measurements, suggesting MRI can evaluate the intraoperative space for the Vertiflex ISS procedure. Preoperative MRI measurement may help decrease complications by aiding in surgical decision-making through providing a reference for intraoperative measurements. Further prospective study is necessary to determine if preoperative MRI measurement can predict and potentially replace the need for intraoperative measurement.

Review of Endosaccular Flow Disrupters for Wide-Neck Aneurysm Treatment.

Endosaccular flow disruption has emerged as a transformative approach for treating wide-neck intracranial aneurysms, which are characterized by neck diameters exceeding 4 millimeters or dome-to-neck ratios below 2. This review examines the technical specifications and clinical outcomes of major endosaccular devices, including the Woven EndoBridge (WEB) device, the Artisse embolization device, the Medina embolization device, the neck bridging device for bifurcation aneurysms, the polycarbonate urethane membrane-assisted device, the Galaxy saccular endovascular aneurysm lattice, and the Contour Neurovascular System. Analysis of pivotal trials reveals varying degrees of efficacy and safety across platforms. The WEB device demonstrated complete occlusion rates of 51.7% to 56.1% at 1 year, with adequate occlusion reaching 84.6% in the WEB Intrasaccular Therapy Study trial and sustained improvement in 76.8% of cases at 5 years. The Artisse system showed initial promise but concerning declines in adequate occlusion from 66.7% at 6 months to 57.1% at 36 months. More recent innovations such as the Galaxy SEAL device achieved complete occlusion in 76.9% of cases in preliminary studies in 1 year. Thromboembolic complications occurred in 12.9% to 17.7% of cases across devices though procedure-related mortality remained below 2%. While the WEB device has established a robust safety and efficacy profile through long-term follow-up data, newer technologies demonstrate promising early results but require extended surveillance. Current challenges focus on optimizing device sizing, improving delivery systems, and enhancing material properties to maximize occlusion rates while minimizing complications. The evolution of these technologies continues to expand treatment options for complex aneurysms previously challenging to address through conventional endovascular or surgical approaches.

The role of transesophageal echocardiography in improving device size selection for percutaneous paravalvular leak closure

Abstract Introduction Paravalvular leak (PVL) is an undesirable complication that can occur following valve implantations. The incidence of major leaks, which can clinically manifest as heart failure, hemolytic anemia, or both, has been reported to be 1-5% (1). The mortality rates for redo surgery are reported at 13%, 15%, and 37% for the first, second, and third operations, respectively (2). In recent years, percutaneous PVL closure (PPVLC) procedures, which are associated with lower mortality rates, have emerged as an attractive option for patients who are at high surgical risk. Purpose Determining the appropriate device size for closing a defect is one of the most challenging aspects of PPVLC. Currently, there is no consensus on the optimal imaging modality for this purpose. We aimed to compare transthoracic and transesophageal echocardiographic measurements to accurately determine the device size. Methods We reviewed our hospital records to identify patients diagnosed with moderate-severe and severe PVL from 2018 to 2024. A total of 81 who underwent percutaneous paravalvular leak closure (PPVLC) patients were evaluated. Eight of these 81 patients were excluded due to unsuccessful PPVLC, leaving 73 patients who were successfully treated with PPVLC were included. Technical success was defined as the deployment of the device without any interference with the prosthetic valve and with mild or less residual regurgitation. The defect size for all patients was evaluated using 2D transthoracic echocardiography (TTE), 2D transesophageal echocardiography (TEE), direct measurement of 3D TEE vena contracta, and 3D multi-planar reconstruction TEE (3D-MPR TEE). Results A total of 73 patients with clinically significant moderate to severe or severe mitral and/or aortic paravalvular leak (PVL) were included in the study. Among these patients, 42 underwent aortic PPVLC and the remaining 31 underwent mitral PPVLC. Patients were categorized based on the implanted device size: 17 patients in the 6-7 mm group, 19 patients in the 8 mm group, 15 patients in the 10 mm group, 8 patients in the 12 mm group, and 14 patients in the 14-16 mm group. According to proportional odds logistic regression analysis, the 3D MPR TEE measurement was the strongest predictor of device size accuracy, both in the overall group and within the aortic/mitral subgroups. In the mitral subgroup, however, the predictive power of direct measurement of 3D TEE vena contracta and 3D MPR measurements was similar. Conclusion PPVLC has gained increasing interest, particularly over the last decade. Determining the appropriate device size is especially challenging in cases of mitral PVL. Our findings suggest that using 3D-MPR TEE measurements significantly improves the accuracy of device size selection in both mitral and aortic PVL. Additionally, direct measurement of 3D TEE vena contracta can serve as a viable alternative for patients with mitral PVL. Figure 1. Direct measurement of 3D TEE Figure 2. 3D TEE MPR measurement

Left atrial appendage: a comparative analysis using 2D and 3D transoesophageal echocardiography

Abstract Background Percutaneous left atrial appendage (LAA) closure is an alternative intervention to anticoagulation to prevent stroke in patients with atrial fibrillation with a higher risk of bleeding. The imaging of LAA is crucial to determine the optimal ostium dimensions for safe closure and procedural outcomes. Sizing using three-dimensional transoesophageal echocardiography (3D-TOE) is likely to offer a more accurate assessment, as seen in other structural interventions such as annular measurements in transcatheter aortic valve implantation (TAVI). Aim This study aimed to evaluate the accuracy of LAA sizing using two-dimensional transesophageal echocardiography (2D-TOE) and 3D-TOE. Furthermore, we assessed the accuracy of the measurements by correlating both imaging modalities with final device size and post-device leakage. Methods Our study prospectively analysed the LAA dimensions of 63 consecutive patients undergoing transoesophageal echocardiography (TOE) with measurements using both 2D and 3D-TOE (Figure 1 &amp; 2). The assessing clinician remained blinded to measurements that were performed retrospectively by data analysts. Additionally, we retrospectively evaluated outcomes with 25 consecutive LAA closures (Figure 3 &amp; 4), where 2D-TOE was utilised alongside fluoroscopy for sizing in 18 (72%), and 3D-TOE was employed in 8 (32%) of patients. Results The mean age of patients was 76 ± 7 years. The LAA annulus was eccentric in 47 (75%) and circular in 16 (25%) of patients. There was a good intraclass correlation (ICC) between 2D and 3D-TOE (ICC=0.81, p &amp;lt;0.001) and Pearson’s correlation (r=0.84, p &amp;lt;0.001). Bland-Altmann analysis (Figure 5) revealed a bias of 0.19, indicating 3D-TOE LAA measurements were larger overall, with limits of agreement between -0.33cm to 0.71cm. The retrospective analysis showed that 2D-TOE underestimated the final device size by 1.86 ± 1.1 mm, while 3D-TOE underestimated by 0.6 ± 1.2 mm. Clinically, using only 2D-TOE measurements, 9 patients (36%) required upsizing, whereas 3D-TOE accurately predicted the final device size in all but one case. Additionally, in 18 cases guided solely by 2D-TOE, 9 (50%) were complicated by post-device leakage at the six-week follow-up, albeit they were all leaks were less than the guideline cut-off value of 6 mm. In contrast, for 8 patients where 3D-TOE was also used, there was only one case of post-device leak. Conclusion Our study demonstrates that while 2D and 3D-TOE values are mostly consistent, 3D-TOE measurements are larger and more accurately depict the irregular, eccentric nature of LAA orifices. 3D-TOE guidance had better correlation with true device size, resulting in lower post-device leakage and less intra-procedural upsizing. These findings align with TAVI literature, which notes that 2D echocardiography underestimates the true size of the aortic valve annulus compared to CT and 3D echocardiography techniques.

Mitral valve annulus assessment: a comparison between 3D-TOE, CCT and surgical ring

Abstract Background Advances in minimally invasive cardiac surgery require accurate preoperative assessment of the morphology and function of the mitral valve apparatus. The success of mitral valve repair with annuloplasty depends on the correct sizing of the mitral annulus ring (1) (2). Three-dimensional transoesophageal echocardiography (3D-TOE) has been proven to be essential for the anatomo-functional characterization of mitral valve apparatus in patients undergoing surgically mitral valve repair (3). It also allows the measurement of quantitative parameters useful in determining the size of the annuloplasty ring, such as A2 height, intertrigonal distance, intercommissural diameter and total annular perimeter size. Cardiac computed tomography (CCT) plays a key role for device sizing in patients undergoing transcatheter mitral valve replacement (4); it is the gold standard for geometric characterisation of the mitral valve and assessment of the spatial relationship of the mitral valve apparatus to adjacent anatomical structures. Several studies have compared CCT with 3D-TOE in sizing the mitral valve apparatus (6) (7); few studies have compared mitral valve apparatus measurements obtained by 3D-TOE and CCT with those obtained intraoperatively by the surgeon, which is the gold standard. Purpose To compare intra-operatively 3D-TOE assessment of mitral valve apparatus with CCT and to compare 3D-TOE and CCT measures with intraoperative surgeon-measured mitral valve annulus. Methods and results We used a cohort of thirty patients who underwent surgery for severe primary mitral regurgitation with mitral valve repair using the Carpentier technique with annuloplasty, all of whom had undergone CCT prior to surgery to exclude coronary artery disease. We compared measurements of the mitral annulus (intertrigonal distance and intercommissural distance) obtained by 3D-reconstruction of intra-operative TOE and 2D-short axis CCT reconstruction with the ring measured intraoperatively by the surgeon and then implanted, using intraclass correlation. We found that the intertrigonal distance measured by CCT showed good agreement with the surgical ring (ICC 0.89 [CI 0.330-0.985; p &amp;lt; 0.05]); the intercommissural distance obtained by 3D-TOE also showed good agreement with the surgical ring (ICC 0.81 [CI 0.458-0.936; p &amp;lt; 0.05]), while the intertrigonal distance measured by 3D-TOE showed a moderate agreement with the surgical annulus (ICC 0.63 [CI 0.056-0.852; p &amp;lt; 0.05]). We then compared the intraoperative 3D TOE measurements with those obtained by CCT and found excellent agreement when comparing the intertrigonal distance (ICC 0.95 [CI 0.755-0.989; p&amp;lt;0.05]). Conclusions 3D-TOE can be considered as a first-line imaging technique to assess the anatomical features of the mitral valve apparatus, not only in patients undergoing cardiac surgery, but also in those undergoing percutaneous interventions or with contraindications to contrast medium CT. 3D-TOE reconstruction Surgical and CCT

Device-assisted transcatheter closure of large secundum atrial septal defects: a novel approach.

Transcatheter closure of large and complex atrial septal defect can pose challenges and complications during device placement. To improve stability, several assistive techniques have been developed. This retrospective study evaluated the efficacy of the device-assisted device closure technique for large secundum atrial septal defects. Patients who underwent device-assisted device closure of atrial septal defect between December 2023 and August 2024 were analysed. Twenty patients (mean age 38.69 years) underwent device closure of large secundum atrial septal defect with device-assisted device closure technique. The mean atrial septal defect diameter was 31.9 mm. The average thick-to-thick measurement was 38.3 mm, which determined the device size. The majority (18 cases) had thin, floppy margins and two had deficient inferior rim. Successful closure was achieved in 18 patients (90%), while two patients (10%) required other methods of assistance. Based on fluoroscopic guidance, patients were divided into two groups: Group A (8 patients) used anteroposterior projection, and Group B (12 patients) used left anterior oblique-cranial view. After initial two failures with anteroposterior view, all cases were successfully closed using left anterior oblique-cranial projection. Device sizes ranged from 36 to 50 mm (median 40 mm). Cocoon devices were used for sizes up to 42 mm, and Occlunix for larger devices. No significant procedural complications occurred, although two patients had minor post-procedural events. Device-assisted device closure technique offers a promising and safe dynamic assistance approach for transcatheter closure of large and challenging atrial septal defects. The left anterior oblique-cranial view showed promising results, though without statistical significance. While results are encouraging, larger prospective studies are needed to validate its effectiveness.

Simulation-Based Design of a Cam-Driven Hydraulic Prosthetic Ankle

Background/Objectives: A cam-driven hydraulic prosthetic ankle was designed to overcome the weaknesses of commercial prostheses and research prototypes, which largely fail to mimic the energy-recycling behaviour of an intact ankle, resulting in poor walking performance for lower-limb prosthesis users. Methods: This novel device exploits miniature hydraulics to capture the negative work performed during stance, prior to push-off, in a hydraulic accumulator, and return positive work during push-off for forward body propulsion. Two cams are used to replicate intact ankle torque profiles based on experimental data. The design process for the new prosthesis used a design programme, implemented in MATLAB, based on a simulation of the main components of the prosthetic ankle. Results: In this paper, we present the design programme and explain how it is used to determine the cam profiles required to replicate intact ankle torque, as well as to size the cam follower return springs. Moreover, a constraint-based preliminary design investigation is described, which was conducted to size other key components affecting the device’s size, performance, and energy efficiency. Finally, the feasible design alternatives are compared in terms of their energy losses to determine the best design with regard to minimising both energy losses and device size. Conclusions: Such a design approach not only documents the design of a particular novel prosthetic ankle, but can also provide a systematic framework for decomposing complex design challenges into a series of sub-problems, providing a more effective alternative to heuristic approaches in prosthetic design.

Scale effects in BEOL compatible ferroelectric field-effect transistor memories with random phase fluctuation

Abstract In this study, we investigate the effects of dimensional scaling on device variation of back-end-of line (BEOL)- compatible ferroelectric field-effect transistor (FeFET) memory with amorphous oxide-semiconductor channel by considering random ferroelectric/dielectric (FE/DE) phase fluctuation. Our study based on TCAD simulation indicates that: i) For a given FE phase, scaling gate length not only improves memory window (MW) due to the sufficient ferroelectric switching during erase, but also increases MW variation (σMW), which is mainly dominated by high-voltage threshold (HVT) variation induced by erase operation. ii) For a given device size, reducing FE phase results in decreased MW with increased σMW. This σMW degradation could be suppressed at longer gate length due to the weak erase. iii) For gate width scaling, it has negligible effect on MW but induces the σMW increase, which could be ascribed to the increased probability of forming DE paths with larger grain-to-channel area ratio. Therefore, although scaling BEOL FeFET device size could increase MW, the increased σMW due to random FE/DE phase fluctuation may also need to be considered. These findings may provide insights for future FeFET design.&amp;#xD;

Design and Validation of a High-Fidelity Left Atrial Cardiac Simulator for the Study and Advancement of Left Atrial Appendage Occlusion.

Atrial fibrillation (AF) is the most common chronic cardiac arrhythmia that increases the risk of stroke, primarily due to thrombus formation in the left atrial appendage (LAA). Left atrial appendage occlusion (LAAO) devices offer an alternative to oral anticoagulation for stroke prevention. However, the complex and variable anatomy of the LAA presents significant challenges to device design and deployment. Current benchtop models fail to replicate both anatomical variability and physiological hemodynamics, limiting their utility. This study introduces a novel left atrial cardiac simulator that incorporates patient-derived LAA models within a benchtop circulatory flow loop, enabling high-fidelity LAAO device testing and development. A rigid, patient-derived left atrium (LA) model was 3D printed from segmented MRI data and modified to accommodate attachment of patient-specific LAA models. A library of LAA geometries was fabricated using silicone casting techniques to replicate the mechanical properties of native tissue. The LA-LAA model was integrated into a circulatory flow loop equipped with a pulsatile pump, pressure sensors, and flow probes, allowing real-time hemodynamic analysis. System tunability was demonstrated by varying heart rate, stroke volume, resistance, and compliance to simulate physiological and pathological conditions. The simulator accurately replicated LA pressure and flow waveforms, closely approximating physiological conditions. Changes in heart rate, stroke volume, and compliance effectively modulated LAP and LA inflow before and after LAAO. Distinct pressure and flow waveforms were observed with different LAA geometries. Hemodynamic analysis revealed increased left atrial pulse pressure after occlusion, with the greatest increase occurring after complete exclusion of the LAA. The simulator facilitated the evaluation of LAAO device performance, including metrics such as seal and PDL, and served as an effective training tool for iterative device deployment and recapture with visual and imaging-guided feedback. The left atrial cardiac simulator offers a highly tunable and realistic platform for testing and developing LAAO devices. It also serves as an effective procedural training tool, allowing for the simulation of patient-specific anatomical and hemodynamic conditions. By enabling these advanced simulations, the simulator enhances pre-procedural planning, device sizing, and placement. This innovation represents a significant step toward advancing personalized medicine in atrial fibrillation management and improving LAAO outcomes.

Compact and aberration effects-shielded objective intraocular scatter measurement system

The measurement of the double-pass (DP) point spread function (PSF) provides an objective, non-invasive method for estimating intraocular scatter in the human eye. In this paper, we propose a compact double-pass objective intraocular scatter measurement system that eliminates the influence of aberrations. The system includes a far-field DP PSF detection channel and a Shack-Hartmann wavefront aberration detection channel, which are used to obtain the far-field DP PSF image and 7 orders Zernike aberration coefficients, respectively. The far-field DP PSF image is used to calculate the initial objective scatter index of the human eye. The aberration coefficients are used to reconstruct the DP PSF image caused by aberrations and calculate the influence coefficient of aberrations on intraocular scatter. By subtracting this influence coefficient from the initial objective scatter index (OSI0), the effect of aberrations on scatter measurement can be eliminated, resulting in an accurate objective scatter coefficient. Experimental verification showed that when the exit pupil aperture of this system was set to 4 mm and 6 mm, the measurement accuracy increased by at least 11.9% and 28.9%, respectively, compared to before eliminating the influence of aberrations. While improving the measurement accuracy, the system also keeps the device size and manufacturing costs at a low level, making it more suitable for clinical applications.

Characterizing optical behavior of automotive metal flake-pigmented coating systems using reflectance transformation imaging

Abstract Metal flake-pigmented coatings are widely appreciated for their eye-catching appearance, and understanding their physical and optical properties is crucial for the automotive coatings industry. The metal flakes loaded in these coatings are optically anisotropic, with their sparkle change based on illumination and viewing angles. These tiny micro-mirrors exhibit various local angular reflections (LARni), and it is interesting to characterize their type-dependent optical behavior. In this study, we employed a reflectance transformation imaging (RTI) system to quantify the mean local angular reflectance (M-LARe) index of metal flakes in automotive metallic coatings. We first captured multi-light image collections (MLICs) from seven automotive metal flake-pigmented coatings, followed by a series of processing steps to extract the flakes’ LARni. The extracted LARni were then normalized, both radiometrically and geometrically, and used to compute the proposed type-dependent index, which is independent of the device and flake size and orientation. Finally, the M-LARe index histograms of the coatings were derived, and the seven samples were ranked according to their reflective capacity. We also observed a meaningful dependency between the mean value of the proposed M-LARe indices for each sample and its sparkle grade at 15°. Potential uncertainties, such as resin type, coating thickness, and metal flake count, were also acknowledged.

Volt/VAr Regulation of the West Mediterranean Regional Electrical Grids Using SVC/STATCOM Devices With Neural Network Algorithms

ABSTRACTReactive power compensation is now a challenging issue in maintaining adequate power quality and improving the performance of the transmission system. Many researchers have focused on the behavior of voltage in the unbalanced state, and the majority of the studies have been done with STATCOM. In this study, the increasing power demand in power grids and the challenges associated with maintaining power quality and stability are discussed. The power system in the western Mediterranean region of Turkey is modeled with the DigSILENT Power Factory program using real data. It highlights the importance of reactive power compensation and introduces FACTS devices as a solution to control power factors and reactive power in the grid. In the realistic model, voltage and reactive power regulation is achieved by using SVC and STATCOM devices to ensure voltage stability. A load flow and short circuit analysis is performed on the designed transmission system for a number of critical scenarios. The modeled power system is optimized for the size and location of the FACTS devices by applying genetic algorithms (GAs) and particle swarm optimization (PSO) algorithms to the selected busbars of the FACTS devices, a strategy designed to significantly reduce system losses. The load values used in the heuristics differ from those used in other studies in that they use a realistic load profile that varies randomly and instantaneously over the long term, as opposed to a fixed load profile. All the comparative results show that the STATCOM controller can maintain the most significant reduction in technical losses and excellent performance in controlling the reactive power response under various outages. The effectiveness of the proposed methodology has been validated in various outage scenarios, and it has been shown that it will reduce the total cost of electricity generation in the western Mediterranean region on an annual basis. Considering the results of the Turkish National Transmission System, increasing voltage sensitivity and reactive power control can be beneficial in reducing power transmission costs and maintaining the balance between generation and consumption.

Delayed Aneurysm Rupture Following Endovascular Treatment with Contour Device: A Case Report.

Delayed rupture of intracranial aneurysms after endovascular treatment is a rare but serious complication. We report the first documented case of late aneurysmal rupture following treatment with a Contour intrasaccular device. A patient in their 60s with a basilar tip aneurysm underwent endovascular treatment using a 14-mm Contour device. Fifteen months later, the patient presented with a fatal intraventricular hemorrhage, and imaging revealed device displacement and aneurysm growth. This case underscores the importance of meticulous device sizing and follow-up, especially for large aneurysms.

Optimizing FACTS Device Placement Using the Fata Morgana Algorithm: A Cost and Power Loss Minimization Approach in Uncertain Load Scenario-Based Systems

Today, reliable power delivery and increasing demand are important issues in modern power systems. Flexible Alternating Current Transmission Systems (FACTS) devices are used to control transmission line parameters to increase power transfer and stability. Nevertheless, the problem of determining the optimal placement and sizing of these devices is still challenging, as the placement and sizing of the devices affects generation costs, power losses, voltage stability, and system reliability. This study proposes the Fata Morgana Algorithm (FATA), an optimization algorithm inspired by the natural process of mirage formation to optimize placement and sizing of FACTS devices in an IEEE 30 bus system with wind turbine integration. The FATA algorithm is evaluated against recently developed and improved optimization techniques, such as rime-ice formation phenomenon based Improved RIME (IRIME) Algorithm, Newton–Raphson-Based Optimization (NRBO), Resistance Capacitance Algorithm (RCA), Krill Optimization Algorithm (KOA), and Grey Wolf Optimizer (GWO), across multiple optimization objectives: reduction in generation cost, reduction in power loss and combined generation cost plus power loss, termed as Gross cost function. Results obtained show that FATA consistently outperforms the other algorithms in terms of convergence and solution quality, offering a robust approach to solving single objective optimization problems. FATA theoretically provides a good balance between exploration and exploitation, and produces better global solutions. It practically increases power system efficiency by lowering operational costs and losses and improving stability. Results indicate that the FATA algorithm produced minimum generation cost of 807.0405 $/h, which is 0.088–0.426% less than the competing algorithms. It also reduced power losses to 5.5917 MW, which is 1.095–6.781% less than other methods. For gross cost minimization, the FATA algorithm achieved a minimum gross cost of 1366.3727 $/h, which is 0.4799% better than the next best algorithm and 3.2261% better than the worst. The results also show that FATA is robust in solving complex optimization problems in power systems, and it provides significant improvements in run time and convergence efficiency. The main advantage for readers is that FATA provides a reliable and efficient way to optimize power systems. Future work could also investigate the application of FATA in real time, as well as in larger power networks with more renewable energy sources.