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LEFMIS: locally-oriented evaluation framework for medical image segmentation algorithms
摘要： This article proposes a novel framework for the locally-oriented evaluation of segmentation algorithms (LEFMIS). The presented approach is robust and takes into account local inter/intra-observer variability and the anisotropy of medical images. What is more, the framework makes it possible to distinguish types of error locally. These features are crucial in the context of cancer image data. The proposed framework is based on use of the signed anisotropic Euclidean distance transform and the distance projection. It can be used easily in many different applications with or without additional expert outlines (both inter- and intra-observer variability). The performance of the proposed framework is depicted using both artificial and kidney cancer CT data with experts’ manual outlines. In the article, in the case of artificial data, it is presented that the manual outlines dispersion is symmetric in relation to the truth border. The effectiveness of the selected segmentation algorithm was analysed in the context of kidney cancer using computed tomography data. For the calculated local inter-observer variability, 80.11% of the surface points generated by the kidney segmentation algorithm are within one expert outline standard deviation and 97.96% are within five. An error distribution shift in the direction of type I error equivalent was also observed. Finally, the significance of the local estimation of error type differences is presented. The article shows the greater usefulness and flexibility of the proposed framework in comparison to the state-of-the-art methods. The exemplary usage of the LEFMIS with or without inter-/intra-observer variability is also presented.
关键词： evaluation,validation,cancer images,intraobserver variability,kidney segmentation,interobserver variability,error types
更新于2025-09-23 15:23:52
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Preparation and optical properties of angle-dependent photonic crystals based on multi-layer films
摘要： The CreSiO2 photonic crystals, featured with two-dimensional structure and optical variation, was prepared by magnetron sputtering and electron beam lithography method. The finite difference time domain method (FDTD) is used to study the light-modulated characteristics of photonic crystals. Hue difference (⊿H) was used to evaluate the optical variations of photonic crystals, and bigger ⊿H indicates stronger angle dependency of color variation. Various parameters are analyzed for their impact upon ⊿H, including hole geometry (radium, r), hole gap (distance between the centers of two circles, d) and hole depth (h). The results matched the ones from simulation. Carbon quantum dots and up-conversion nanocrystals NaYF4 were inserted into the photonic crystals, and testing results of these doped crystals showed optical variation of fluorescence in the UV and IR region.
关键词： Finite difference time domain,Multi-layer films,Photonic crystal,Optical variability
更新于2025-09-23 15:23:52
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Speckle tracking echocardiography in healthy children: comparison between the QLAB by Philips and the EchoPAC by General Electric
摘要： Speckle tracking echocardiography (STE) has become a useful tool in cardiology but remains scarcely developed in pediatrics. We aimed to evaluate the feasibility of STE analyses in healthy children and compare reliability of STE for left and right ventricles (LV, RV) between the EchoPAC (GE Healthcare) and the QLAB (Philips Healthcare) software systems. Healthy children were screened for this prospective cross-sectional study. Analyses were performed upon five levels of variability: intra/inter-ultrasound system, intra/inter-sonographer and intra/inter-analyzer. The feasibility was measured, and the tracking quality informed. The study included 156 healthy children. Mean age was 7.6 ± 5 years [1 month–16.8 years]. Conventional echocardiography variables were similar in both ultrasound systems. For both software brands, the tracking quality was excellent in the LV longitudinal and circumferential displacements, but more limited in the RV free wall longitudinal strain. Inter-ultrasound system correlation was poor for global longitudinal and circumferential LV strain (ICC of 0.34 [IC95% 0.06–0.57]) and 0.12 [IC95% ? 0.18 to ? 0.40], respectively). We observed poor inter-sonographer reliability for both global LV longitudinal strain and global LV circumferential strain with the two software systems. Inter-analyzer variability was good especially for the global LV circumferential strain using Philips software (ICC of 0.78 [IC95% 0.52–0.91]). In pediatrics, the Philips/GE inter-vendor level of variability in STE analysis is mainly due to inter ultrasound systems and inter sonographers’ differences. These results need to be taken into account when using STE analysis in the follow-up of cardiac children. Clinicaltrials.gov: NCT02056925.
关键词： Variability,Pediatrics,Inter-vendor,Pediatric cardiology,2D strain
更新于2025-09-23 15:23:52
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An Outlier-insensitive Unmixing Algorithm with Spatially Varying Hyperspectral Signatures
摘要： Effective hyperspectral unmixing (HU) is essential to the estimation of the underlying materials’ signatures (endmember signatures) and their spatial distributions (abundance maps) from a given image (data) of a hyperspectral scene. Recently, investigating HU under the non-negligible endmember variability (EV) and outlier effects (OE) has drawn extensive attention. Some state-of-the-art works either consider EV or consider OE, but none of them considers both EV and OE simultaneously. In this paper, we propose a novel HU algorithm, referred to as the variability/outlier-insensitive multi-convex unmixing (VOIMU) algorithm, that is robust against both EV and OE. Considering two suitable regularizers, a nonconvex minimization problem is formulated for which the perturbed linear mixing model (PLMM) proposed by Thouvenin et al., is used for modeling EV, while OE is implicitly handled by applying a p quasi-norm to the data fitting with 0 < p < 1. Then we reformulate it into a multi-convex problem which is then solved by the block coordinate decent (BCD) method, with convergence guarantee by casting it into the block successive upper bound minimization (BSUM) framework. The proposed VOIMU algorithm can yield a stationary-point solution with convergence guarantee, together with some intriguing information of potential outlier pixels though outliers are neither physically modeled in the above problem nor detected in the algorithm operation. Finally, we provide some simulation results and experimental results using real data to demonstrate the efficacy and practical applicability of the proposed VOIMU algorithm.
关键词： block successive upper bound minimization (BSUM),endmember variability,alternating direction method of multipliers (ADMM),outlier effects,block coordinate decent (BCD) method,Hyperspectral imaging
更新于2025-09-23 15:22:29
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Soil Temperature Variability in Complex Terrain Measured Using Fiber-Optic Distributed Temperature Sensing
摘要： Soil temperature (Ts) exerts critical controls on hydrologic and biogeochemical processes, but the magnitude and nature of Ts variability in a landscape setting are rarely documented. Fiber-optic distributed temperature sensing (DTS) systems potentially measure Ts at high density across a large extent. A fiber-optic cable 771 m long was installed at a depth of 10 cm in contrasting landscape units (LUs) defined by vegetative cover at Upper Sheep Creek in the Reynolds Creek Experimental Watershed (RCEW) and Critical Zone Observatory in Idaho. The purpose was to evaluate the applicability of DTS in remote settings and to characterize Ts variability in complex terrain. Measurement accuracy was similar to other field instruments (±0.4°C), and Ts changes of approximately 0.05°C at a monitoring spatial scale of 1 m were resolved with occasional calibration and an ambient temperature range of 50°C. Differences in solar inputs among LUs were strongly modified by surface conditions. During spatially continuous snow cover, Ts was practically homogeneous across LUs. In the absence of snow cover, daily average Ts was highly variable among LUs due to variations in vegetative cover, with a standard deviation (SD) greater than 5°C, and relatively uniform (SD < 1.5°C) within LUs. Mean annual soil temperature differences among LUs of 5.2°C was greater than those of 4.4°C associated with a 910-m elevation difference within the RCEW. In this environment, effective Ts simulation requires representation of relatively small-scale (<20 m) LUs due to the deterministic spatial variability of Ts.
关键词： landscape units,complex terrain,vegetative cover,fiber-optic cable,snow cover,spatial variability,Soil temperature,distributed temperature sensing
更新于2025-09-23 15:22:29
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Télédétection satellitaire des surfaces enneigées et englacées
摘要： This article presents an overview of recent advances in remote sensing applied to the study of snow and glacierized areas, in which the French scientific community has been involved. Whatever the type of satellite data, optical, radar, lidar or gravimetric, these works on seasonal or perennial snow cover, mountain glaciers, ice caps, sea ice, and lake or river ice, aim at documenting both the physical characteristics of these objects and their spatial and temporal variability at local, regional or global scales.
关键词： glaciers,remote sensing,snow,ice,spatial variability,satellite data,temporal variability
更新于2025-09-23 15:21:21
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[IEEE 2019 8th International Conference on Renewable Energy Research and Applications (ICRERA) - Brasov, Romania (2019.11.3-2019.11.6)] 2019 8th International Conference on Renewable Energy Research and Applications (ICRERA) - Stable Operation of an Automotive Photovoltaic System under Moving Shadows
摘要： This paper presents a simple mathematical expression to model the effect of statistical dopant fluctuations on threshold voltage (Vth) of junction field-effect transistors (JFETs). The random discrete doping (RDD) in the active device area is used to derive an analytical model to compute the standard deviation, σ Vth,RDD of the Vth-distribution for any arbitrary channel doping profiles. The model shows that the Vth-variability in JFETs depends on the active device area, channel doping concentration, and the depth of the channel depletion region of the gate/channel pn-junction. The model is applied to compute σ Vth,RDD for symmetric and asymmetric source/drain double-gate n-channel JFETs. The simulation results show that the model can be used for predicting Vth-variability in JFETs.
关键词： statistical dopant fluctuations,random discrete doping,process variability in JFETs,modeling threshold voltage variability,JFET threshold voltage variability,Junction field-effect transistor (JFET)
更新于2025-09-23 15:21:01
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Classifying ground-measured 1?minute temporal variability within hourly intervals for direct normal irradiances
摘要： Variability of solar surface irradiances in the 1 minute range is of interest especially for solar energy applications. Eight variability classes are defined for the 1 minute resolved direct normal irradiance (DNI) variability inside an hour. They combine high, medium, and low irradiance conditions with small, medium, and large scale variations from one minute to the next minute. A reference data base of 333 individual hours with ground-based 1 minute DNI observations was created by expert review from one year of observations at the BSRN station in Carpentras, France. Each variability class is represented by 16 to 63 members. Variability indices as previously published or newly suggested are used as classifiers to detect the class members automatically. Up to 77 % of all class members are identified correctly by this automatic scheme. The variability classification method allows the comparison of different project sites in a statistical and automatic manner to quantify short-term variability impacts on solar power production.
关键词： variability,ground-based observations,direct irradiance,global horizontal irradiance,automatic classification
更新于2025-09-23 15:21:01
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USING PHOTOPLETHYSMOGRAPHY IMAGING FOR OBJECTIVE CONTACTLESS PAIN ASSESSMENT
摘要： This work presents an extension to the known Analgesia Nociception Index (ANI), which provides an objective estimation of the current depth of analgesia. An adequate “measure” would facilitate so-called balanced anesthesia. Generally, ANI is computed using heart rate variability or rather beat-to-beat intervals based on an electrocardiogram (ECG). There are clinical situations where no ECG monitoring is available or required, but only photoplethysmography (PPG), e.g., in some cases in postoperative care or pain therapy. In addition, a combination of PPG and ECG for obtaining beat-to-beat intervals may lead to increased robustness and reliability for dealing with artifacts. This work therefore investigates the computation of ANI using standard PPG. In addition, new methods and opportunities are presented using contactless PPG imaging (PPGI). PPGI?enables contactless PPG recordings for deriving beat-to-beat intervals as well as analysis of local perfusion and wounds.
关键词： PPG,nociception,image based PPG,anesthesiology,ECG,pain,analgesia,heart rate variability,PPGI
更新于2025-09-23 15:21:01
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A Novel Topology for Process Variation-Tolerant Piezoelectric Micromachined Ultrasonic Transducers
摘要： This paper presents a novel architecture for piezoelectric micromachined ultrasonic transducers (PMUT) allowing for a drastic reduction in the impact of process variations on the accuracy of the resonant frequency. At the core of this new topology is a toroidal anchoring technique. Measurement results show that inter- and intra-die resonant frequency standard variations can be reduced from 101 kHz to 23 kHz and from 20 kHz to 5.9 kHz, respectively, by using the method proposed in this paper, showcasing devices fabricated using the PiezoMUMPs commercial fabrication technology. From the 16 chips that have been fabricated, each holding 12 PMUT devices of two different topologies, resonant frequency results are presented and analyzed to assess the effectiveness of the proposed approach. In addition, as a proof of concept, the fabricated PMUT are demonstrated to perform distance ranging measurements.
关键词： frequency,ranging measurements,variability,process variation,MEMS,PMUT,Piezoelectric ultrasonic transducers,microfabrication
更新于2025-09-23 15:21:01