bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improving the ambiguity resolution with the consideration of unmodeled errors in GNSS medium and long baselines
Authors: Wang Jiafu , Yu Xianwen 
Published: July 2024

Abstract
Ambiguity resolution (AR) is fundamental to achieve high-precision solution in global navigation satellite system relative positioning. Extensive research has shown that systematic errors are associated with the performance of AR. However, due to the physical complexity, some systematic errors would inevitably remain in the observation equations even after processed with some popular models and parameterization. In the medium and long baselines, these unmodeled errors are the leading cause of the slow or even incorrect fixation of ambiguity. Therefore, to improve the AR performance in the medium and long baselines, we present a procedure with the careful consideration of unmodeled errors. At first, we develop a method to estimate the unmodeled errors based on the float ambiguity bias. Then, the overall procedure and key steps to fix the float solutions corrected by the unmodeled error estimate is designed. Finally, some real-measured baselines (from 68 km to 120 km) are utilized to validate the proposed procedure. The experimental results are analyzed and discussed from the aspects of AR and positioning, respectively. For the AR performance, the time required for the first fixing have been reduced by about 41.58%–83.51%, from 12 to 100 min. Besides, 12.72%–48.59% and 2.96%–36.28% improvements of the ambiguity-fixed rate and the ambiguity-correct rate can be respectively obtained in the four baselines. As for the positioning performance, the mean values and RMSEs have improved by 0.2–4.8 cm (1.63%–22.43%) and 0.2–2.8 cm (1.47%–10.57%), respectively.
Research on transformer based online condition monitoring method for IPM
Authors: Tang Shengxue , Zhao Jinze , Tan Liqiang , Yan Jinjing 
Published: July 2024

Abstract
The Intelligent Power Module (IPM) has the integrated packaging, leading to the advantages of convenient use, safety and reliability. However, once it fails, it will cause the whole power supply system to be inoperative, and it is necessary to perform online Condition Monitoring (CM) of the IPM. In this paper, we extract the aging characteristics such as dynamic equivalent resistance, peak-to-peak value, switching frequency, and turn-off time only from the voltage and current of IPM drain–source port, and then propose a non-intrusive online CM method for the IPM based on the transformer neural network (TNN). We analyse the internal aging mechanism of the IPM, the changing law of aging features, and construct multi-dimensional aging fusion features, and then the TNN model is used to monitor early parameters drift of multi-dimensional fusion feature vectors and realize the accurate online prediction of IPM health condition. The experimental analysis results show that the fault prediction accuracy reaches 96%, and can realize the health CM under the condition of noise interference, weak aging features and few external observable points.
High-precision tropospheric correction method for NRTK regions with significant height differences
Authors: Lei Xiaoting , Xu Xiaolong , Tao Jun , Yang Tianyu , Zhao Qile , Guo Jing 
Published: July 2024

Abstract
In response to the issue of poor network real-time kinematic (NRTK) service performance in regions with significant height differences, an improved tropospheric height correction (ITHC) method is proposed. Precise point positioning (PPP) is employed to compute the troposphere delay at base stations. Subsequently, a tropospheric vertical profile fitting model (TVPFM) is established for the vertical reduction of the troposphere in regions with significant height differences. In this case, the tropospheric errors introduced by the height differences between the base and rover stations can be calculated. Finally, the tropospheric error can be corrected during the generation of virtual observations, ensuring high-accuracy positioning of NRTK rovers. With the troposphere delay computed based on the PPP approach, datum errors introduced by inaccurate tropospheric correction methods are mitigated. To reduce the dependence of the troposphere delay on height, ECMWF reanalysis v5 (ERA5) data are employed to fit the TVPFM. Experimental analysis demonstrates that the troposphere exhibits distinct vertical variation characteristics, allowing for its segmentation into three layers. Consequently, a piecewise TVPFM is established. Observations obtained from the continuously operating reference stations network located in Yunnan, China, are utilized for validation. The selected stations exhibit a maximum height difference of approximately 2 km. The experimental results exhibit a notable enhancement in correction accuracy with the ITHC in comparison to conventional correction methodologies. Specifically, the ambiguity fixing rate demonstrates a noteworthy improvement of 13.3%, accompanied by a substantial increase in positioning accuracy by 51.4%.
EIT probe based intraoperative tissue inspection for minimally invasive surgery
Authors: Guo Jing , Zhuang Baiyang , Li Renkai , Lin Zexuan , Cheng Zhuoqi , Lou Haifang 
Published: July 2024

Abstract
Electrical impedance tomography (EIT) has become an integral component in the repertoire of medical imaging techniques, particularly due to its non-invasive nature and real-time imaging capabilities. Despite its potential, the application of EIT in minimally invasive surgery (MIS) has been hindered by a lack of specialized electrode probes. Existing designs often compromise between invasiveness and spatial sensitivity: probes small enough for MIS often fail to provide detailed imaging, while those offering greater sensitivity are impractically large for use through a surgical trocar. Addressing this challenge, our study presents a breakthrough in EIT probe design. The open electrode probe we have developed features a line of 16 electrodes, thoughtfully arrayed to balance the spatial demands of MIS with the need for precise imaging. Employing an advanced EIT reconstruction algorithm, our probe not only captures images that reflect the electrical characteristics of the tissues but also ensures the homogeneity of the test material is accurately represented. The versatility of our probe is demonstrated by its capacity to generate high-resolution images of subsurface anatomical structures, a feature particularly valuable during MIS where direct visual access is limited. Surgeons can rely on intraoperative EIT imaging to inform their navigation of complex anatomical landscapes, enhancing both the safety and efficacy of their procedures. Through rigorous experimental validation using ex vivo tissue phantoms, we have established the probe’s proficiency. The experiments confirmed the system’s high sensitivity and precision, particularly in the critical tasks of subsurface tissue detection and surgical margin delineation. These capabilities manifest the potential of our probe to revolutionize the field of surgical imaging, providing a previously unattainable level of detail and assurance in MIS procedures.
TEMPy: a toolkit for the modeling of weighted tissue equivalent material in diagnostic imaging
Authors: Boiset Gisell R , Moratta Raphael , Yoshimura Elisabeth M , Costa Paulo R 
Published: July 2024

Abstract

Objective. Accurate simulation of human tissues is imperative for advancements in diagnostic imaging, particularly in the fields of dosimetry and image quality evaluation. Developing Tissue Equivalent Materials (TEMs) with radiological characteristics akin to those of human tissues is essential for ensuring the reliability and relevance of imaging studies. This study presents the development of a mathematical model and a new toolkit (TEMPy) for obtaining the best composition of materials that mimic the radiological characteristics of human tissues. The model and the toolkit are described, along with an example showcasing its application to obtain desired TEMs. Approach. The methodology consisted of fitting volume fractions of the components of TEM in order to determine its linear attenuation coefficient as close as possible to the linear attenuation coefficient of the reference material. The fitting procedure adopted a modified Least Square Method including a weight function. This function reflects the contribution of the x-ray spectra in the suitable energy range of interest. TEMPy can also be used to estimate the effective atomic number and electron density of the resulting TEM. Main results. TEMPy was used to obtain the chemical composition of materials equivalent to water and soft tissue, in the energy range used in x-ray imaging (10 −150 keV) and for breast tissue using the energy range (5–40 keV). The maximum relative difference between the linear attenuation coefficients of the developed and reference materials was ±5% in the considered energy ranges. Significance. TEMPy facilitates the formulation of TEMs with radiological properties closely mimicking those of real tissues, aiding in the preparation of physical anthropomorphic or geometric phantoms for various applications. The toolkit is freely available to interested readers.
Deep learning for intracranial aneurysm segmentation using CT angiography
Authors: Zheng Huizhong , Liu Xinfeng , Huang Zhenxing , Ren Yan , Fu Bin , Shi Tianliang , Liu Lu , Guo Qiping , Tian Chong , Liang Dong , Wang Rongpin , Chen Jie , Hu Zhanli 
Published: July 2024

Abstract

Objective. This study aimed to employ a two-stage deep learning method to accurately detect small aneurysms (4–10 mm in size) in computed tomography angiography images. Approach. This study included 956 patients from 6 hospitals and a public dataset obtained with 6 CT scanners from different manufacturers. The proposed method consists of two components: a lightweight and fast head region selection (HRS) algorithm and an adaptive 3D nnU-Net network, which is used as the main architecture for segmenting aneurysms. Segments generated by the deep neural network were compared with expert-generated manual segmentation results and assessed using Dice scores. Main
Results. The area under the curve (AUC) exceeded 79% across all datasets. In particular, the precision and AUC reached 85.2% and 87.6%, respectively, on certain datasets. The experimental results demonstrated the promising performance of this approach, which reduced the inference time by more than 50% compared to direct inference without HRS. Significance. Compared with a model without HRS, the deep learning approach we developed can accurately segment aneurysms by automatically localizing brain regions and can accelerate aneurysm inference by more than 50%.
Yet anOther Dose Algorithm (YODA) for independent computations of dose and dose changes due to anatomical changes
Authors: Burlacu Tiberiu , Lathouwers Danny , Perkó Zoltán 
Published: July 2024

Abstract

Objective. To assess the viability of a physics-based, deterministic and adjoint-capable algorithm for performing treatment planning system independent dose calculations and for computing dosimetric differences caused by anatomical changes. Approach. A semi-numerical approach is employed to solve two partial differential equations for the proton phase-space density which determines the deposited dose. Lateral hetereogeneities are accounted for by an optimized (Gaussian) beam splitting scheme. Adjoint theory is applied to approximate the change in the deposited dose caused by a new underlying patient anatomy. Main results. The dose engine’s accuracy was benchmarked through three-dimensional gamma index comparisons against Monte Carlo simulations done in TOPAS. For a lung test case, the worst passing rate with (1 mm, 1%, 10% dose cut-off) criteria is 94.55%. The effect of delivering treatment plans on repeat CTs was also tested. For non-robustly optimized plans the adjoint component was accurate to 5.7% while for a robustly optimized plan it was accurate to 4.8%. Significance. Yet anOther Dose Algorithm is capable of accurate dose computations in both single and multi spot irradiations when compared to TOPAS. Moreover, it is able to compute dosimetric differences due to anatomical changes with small to moderate errors thereby facilitating its use for patient-specific quality assurance in online adaptive proton therapy.
Investigations on the beam quality correction factor for ionization chambers in high-energy brachytherapy dosimetry
Authors: Failing T , Hensley F W , Keil B , Zink K 
Published: July 2024

Abstract

Objective. To enhance the investigations on MC calculated beam quality correction factors of thimble ionization chambers from high-energy brachytherapy sources and to develop reliable reference conditions in source and detector setups in water. Approach. The response of five different ionization chambers from PTW-Freiburg and Standard Imaging was investigated for irradiation by a high dose rate Ir-192 Flexisource in water. For a setup in a Beamscan water phantom, Monte Carlo simulations were performed to calculate correction factors for the chamber readings. After exact positioning of source and detector the absorbed dose rate at the TG-43 reference point at one centimeter nominal distance from the source was measured using these factors and compared to the specification of the calibration certificate. The Monte Carlo calculations were performed using the restricted cema formalism to gain further insight into the chamber response. Calculations were performed for the sensitive volume of the chambers, determined by the methods currently used in investigations of dosimetry in magnetic fields. Main results. Measured dose rates and values from the calibration certificate agreed within the combined uncertainty (k = 2) for all chambers except for one case in which the full air cavity was simulated. The chambers showed a distinct directional dependence. With the restricted cema formalism calculations it was possible to examine volume averaging and energy dependence of the perturbation factors contributing to the beam quality correction factor also differential in energy. Significance. This work determined beam quality correction factors to measure the absorbed dose rate from a brachytherapy source in terms of absorbed dose to water for a variety of ionization chambers. For the accurate dosimetry of brachytherapy sources with ionization chambers it is advisable to use correction factors based on the sensitive volume of the chambers and to take account for the directional dependence of chamber response.
A novel scale-bridging method for MSMA linking continuum thermodynamics constitutive formulations to lumped system-level models
Authors: Sordon Fabian , El Khatib Omar , Courant Robert , Jeeja Akshay B , Maas Jürgen , Kiefer Bjoern 
Published: July 2024

Abstract
This work introduces a novel scale-bridging method between a continuum thermodynamics constitutive model and a lumped system-level model for magnetic shape memory alloys (MSMA). With this method, system models for real-time operations are generated based on virtual experiments using the constitutive model. The proposed method addresses the fact that, while constitutive models for MSMA typically only require small sets of parameters as input, their evaluation is still computationally expensive. System models for control engineering, however, require extensive experimental parameterization, while their evaluation is highly time-efficient. The proposed scale-bridging method has the potential to combine a small parameterization effort and a low computational cost of the real-time system model. Additionally, the constitutive model is utilized to investigate whether it can determine the individual behavior of MSMA samples. This is important since the inherent model parameters, while valid for ideal single crystals, deviate for non-ideal MSMA sample behavior. To this end, the MSMA constitutive model, based on a global variational principle originally proposed by Kiefer et al is supplemented by various extensions, including a more robust algorithmic treatment. A parameter identification procedure is introduced to optimize the constitutive model parameters based on an outer hysteresis curve for a particular load case. By conducting virtual experiments with the constitutive model, data sets are generated to parameterize Preisach hysteresis models as numerical approximations of the constitutive models. The resulting hysteresis models are compared with physical experiments using an MSMA test bench for different load cases. It is shown that the proposed scale-bridging method successfully generates hysteresis models derived from constitutive models. While maintaining accuracy comparable to strictly phenomenological models across various load cases (as validated through physical MSMA test bench experiments), these models require significantly less parameterization effort than classical system models. This translates to faster model creation and broader applicability.
Event-triggered semi-active TLCD for ground motion-induced vibration control
Authors: Ding Hao , Zhang Jian , Song Jian , Fang Xiaojun , Wang Jinting 
Published: July 2024

Abstract
One potential drawback of tuned liquid column dampers (TLCDs) is their relatively low control efficiency during the initial stage of structural vibration caused by external excitations. This is because satisfactory control effects can only be achieved when the liquid inside TLCD is fully oscillating, which is not the case during the initial stage. To solve this problem, in this study, an event-triggered semi-active technique is creatively proposed to improve the vibration reduction efficiency of TLCDs during the initial stage. The fundamental idea of the proposed approach is to provide an initial displacement to the liquid column via baffles, and then release the constraints on the initial liquid displacement at an appropriate time to achieve the rapid activation of TLCDs. A strategy from the standpoint of phase difference between liquid column motion and structural motion is proposed to determine the triggering conditions (i.e. when to release the constraints). The effectiveness of the proposed semi-active system is examined under both harmonic and stochastic excitations. The results show that the proposed strategy successfully improves the vibration suppression performance of TLCDs in the early stage of structural vibration.
A theoretical investigation on equilibrium magnetic properties in nanowire arrays
Authors: Kantar Ersin , Ertaş Mehmet 
Published: July 2024

Abstract
The paper focuses on the study of an Ising nanowire array composed of core/shell-structured single nanowires placed at the edges of a square lattice. The phase transition temperature, at which a transition occurs in the magnetic properties, is obtained using effective field theory for two interacting individual nanowires. To understand how the interaction affects the magnetic, we defined the exchange interaction (JR) between the single nanowires. This interaction is assigned both positive and negative values to reveal the ferromagnetic and antiferromagnetic characteristics of the system. Our results revealed that the exchange interaction between individual nanowires significantly influences the magnetic properties of the system.
Exploring negative ion behaviors and their influence on properties of DC magnetron sputtered ITO films under varied power and pressure conditions
Authors: Li 李 Maoyang 茂洋 , Mo 莫 Chaochao 超超 , Ji 季 Peiyu 佩宇 , Zhang 张 Xiaoman 潇漫 , Chen 陈 Jiali 佳丽 , Zhuge 诸 Lanjian 葛兰剑 , Wu 吴 Xuemei 雪梅 , Tan 谭 Haiyun 海云 , Huang 黄 Tianyuan 天源 
Published: July 2024

Abstract
We deposited indium-tin-oxide (ITO) films on silicon and quartz substrates by magnetron sputtering technology in pure argon. Using electrostatic quadrupole plasma diagnostic technology, we investigate the effects of discharge power and discharge pressure on the ion flux and energy distribution function of incidence on the substrate surface, with special attention to the production of high-energy negative oxygen ions, and elucidate the mechanism behind its production. At the same time, the structure and properties of ITO films are systematically characterized to understand the potential effects of high energy oxygen ions on the growth of ITO films. Combining with the kinetic property analysis of sputtering damage mechanism of transparent conductive oxide (TCO) thin films, this study provides valuable physical understanding of optimization of TCO thin film deposition process.
Letter case pairs for SI prefix symbols
Authors: Brown Richard J C 
Published: July 2024

Abstract
This letter considers the potential for confusion in the presentation and interpretation of measurement results caused by the existence of upper- and lower-case letter pairs for SI prefix symbols, an example of this being the newest prefix symbols Q & q and R & r, adopted at the 27th Meeting of the General Conference on Weights and Measures in November 2022. The requirements of digitalisation and machine readability, when making choices for new unit and prefix symbols, are also examined.
ATEP: an advanced transport model for energetic particles
Authors: Lauber Ph. , Falessi M. , Meng G. , Hayward-Schneider T. , Popa V.-A. , Zonca F. , Schneider M. 
Published: July 2024

Abstract
In this paper we report on the implementation and verification of a phase-space resolved energetic particle (EP) transport model. It is based on a first-principle theoretical framework, i.e. the system of non-linear gyrokinetic equations and the related transport equations. Its focus is primarily directed toward understanding the meso-scale character of EPs and its consequences. Compared to the conventional description of thermal radial transport via a one-dimensional radial diffusion equation, the newly developed model is three-dimensional using canonical constants-of-motion (CoM) variables. The model does not assume diffusive processes to be dominant a priori, instead the EP fluxes are self-consistently calculated and directly evolved in CoM space. We use the EP-Stability workflow and the HAGIS code to determine the phase space fluxes explicitly either in the limit of constant mode amplitudes or an energy-conserving quasi-linear model. As an application of the model the transport of neutral-beam-generated EPs due to a toroidal Alfvén eigenmode in an ITER plasma is investigated. As there are no sources and collisions taken into account so far (for an extension of the model see the companion paper (Meng et al 2024 Nucl. Fusion accepted)), the results cannot be considered as an exhaustive study, but rather as a practical demonstration of the conceptual framework on the way to a comprehensive reduced description of burning plasmas.