Field Point Research Articles

Fluid simulations of resistive drift-wave turbulence with diamagnetic flow in ZPED experiments

We derive a diamagnetic resistive fluid model (DRF) and develop an associated two-dimensional fluid simulation code (DRF-2D) to explore the dynamics of resistive drift modes within the plasmas of the Zheda Plasma Experiment Device (ZPED). The validation of the linear dispersion relation for the DRF-2D code revealed a harmonious agreement between analytical theory and linear numerical simulations. Leveraging plasma parameters obtained from the ZPED experiments, we conducted a comprehensive series of nonlinear simulations using the DRF-2D code. Our simulations successfully replicate the nonlinear trends in turbulent fluctuations and transport observed in the ZPED experiments, particularly demonstrating a remarkably accurate alignment of the turning point in the magnetic field. Notably, the DRF model sheds light on the observed frequency sign reversal from the electron diamagnetic direction to the ion diamagnetic direction in the ZPED experiments. This is demonstrated through well-matched turning points in the confining magnetic field between the nonlinear simulations and ZPED experiments. The fidelity of our model in capturing these phenomena underscores its efficacy in providing valuable insights and predictive capabilities for the intricate dynamics observed in the ZPED plasmas.

Reconstruction of measurement data with multiple outliers using novel domain-based RBF

Due to the high accuracy of computation, radial basis function (RBF) is widely recognized as a versatile and effective method for interpolating and approximating discrete points in various fields. However, RBF is quite sensitive to outliers, which can easily lead to distorted results. In this article, a novel overlapped domain-based RBF (ODRBF) method is proposed, in which the concept of effective domain is introduced to build a moving model, and Student’s t-regression and Gaussian mixture model (GMM) clustering are used for dealing with local anomalies. By introducing the effective domain, the estimated points and domain radius are constructed and the global model can be transformed into local estimation models. In each effective domain, a series of estimation models are iteratively generated through Student’s t-regression, and based on the distances between the estimation model and discrete points, GMM clustering is used to subsequently select the data as the input of the next regression. This iterative strategy in each effective domain ensures the removal of multiple outliers. Then, the preserved points in the processed effective domain are used to obtain local estimated value by RBF. The proposed method demonstrates strong robustness to highly contaminated dataset in the reconstruction of the simulation and experimental datasets.

A photogrammetric approach for real‐time visual SLAM applied to an omnidirectional system

AbstractThe problem of sequential estimation of the exterior orientation of imaging sensors and the three‐dimensional environment reconstruction in real time is commonly known as visual simultaneous localisation and mapping (vSLAM). Omnidirectional optical sensors have been increasingly used in vSLAM solutions, mainly for providing a wider view of the scene, allowing the extraction of more features. However, dealing with unmodelled points in the hyperhemispherical field poses challenges, mainly due to the complex lens geometry entailed in the image formation process. To address these challenges, the use of rigorous photogrammetric models that appropriately handle the geometry of fisheye lens cameras can overcome these challenges. Thus, this study presents a real‐time vSLAM approach for omnidirectional systems adapting ORB‐SLAM with a rigorous projection model (equisolid‐angle). The implementation was conducted on the Nvidia Jetson TX2 board, and the approach was evaluated using hyperhemispherical images captured by a dual‐fisheye camera (Ricoh Theta S) embedded into a mobile backpack platform. The trajectory covered a distance of 140 m, with the approach demonstrating accuracy better than 0.12 m at the beginning and achieving metre‐level accuracy at the end of the trajectory. Additionally, we compared the performance of our proposed approach with a generic model for fisheye lens cameras.

Design and Implementation of English Writing Aids Based on Natural Language Processing

The design and implementation of English writing aids based on natural language processing (NLP) involve leveraging advanced algorithms and techniques to assist users in improving their writing skills. These aids can encompass various functionalities such as grammar and spell checking, style suggestions, vocabulary enhancement, and plagiarism detection. By analyzing the context, structure, and semantics of the text, NLP models can provide intelligent feedback and recommendations to help users express themselves more effectively. Additionally, interactive features such as real-time editing and personalized suggestions contribute to a seamless user experience. The paper presents a comprehensive exploration of the Sentimental Random Field Point (SRFP) approach in the domain of natural language processing (NLP). Through a series of experiments and analyses, we investigate the effectiveness and versatility of SRFP across various NLP tasks, including sentiment analysis, named entity recognition, text classification, and machine translation. Our findings demonstrate the robustness of SRFP-based algorithms and models in accurately classifying sentiments, enhancing grammatical correctness, expanding vocabulary, improving writing style, and achieving high performance in classification tasks. Through results it is observed that an accuracy of 92.7% for sentiment analysis using the BERT model, a precision of 85.3% and recall of 88.9% for vocabulary enhancement, and an accuracy of 93.5% for machine translation using the Transformer model.

Numerical investigation on the use of various blade tips for the helicopter's main rotor blade in forward flight regarding aerodynamic performance and HSI noise considerations

The goal of this research is to investigate aerodynamic performance and high-speed impulsive (HSI) noise of various blade tips for the helicopter's main rotor in forward flight. For this purpose, three-dimensional compressible flow field around the rotor blades is numerically simulated by the solution of the unsteady Reynolds averaged Navier-Stokes (URANS) equations with the "SST k-ω" turbulence model. Solution is quantified by the calculation of torque, drag, and thrust coefficients of CQ, CD, CT, and L/D ratio. HSI noise on the rotor plane is assessed by the calculation of sound pressure level at certain points of the flow field using the Ffowcs Williams-Hawking (FW-H) equation. Blade tips are eleven and include anhedral, dihedral, Eagle and combinations of them, and also Blue Edge and rectangular. The combinations are inspired by the tip configurations of the fixed wings. In this regard effects of the tip geometry parameters including curvature and height of its parts have been considered as well. All of the tips are examined for two flight conditions of Caradonna and Tung two-blade rotor with fixed pitch angle and time-varying pitch angles. Based on the present results, it is found that blade tips of dihedral family do not improve the aerodynamic performance of the helicopter blade. Also, addition of anhedral part to the blade tip improves the L/D ratio. According to the present acoustic analysis, it was seen that after the Blue Edge, the Eagle tip stands in order of priority. For the condition of Caradonna and Tung two-blade rotor with tip Mach number of 0.8 and advance ratio of 0.2, HSI noise of the Eagle-tip blade decreases by 2.39 % compared to that of the two-blade rotor with rectangular tip. However, the aerodynamics performance of the Eagle tip is much better than that of the Blue Edge.

Combining six superluminal and subluminal structured light fields with right and left circular polarizations in a chiral medium through superposition

The structured vector fields of circularly polarized light, comprising both left and right (RCP and LCP) beams superposed in the atomic medium are investigated in this work. At resonance in the anomalous/normal dispersion area, both RCP and LCP beams with a non-negative and non-positive group index of ±40 have been recorded. RCP and LCP beam group velocities are enhanced to ±1.5×109m/s at δ=0.15Γ, that is surpassing the speed of light in vacuum, denoted as ”c” leading to superluminal propagation. The RCP is superluminal and the LCP subluminal at the resonance point of the probe field. The group delay for The LCP beam is positive and the RCP beam is non-positive. The worth of the group delay for RCP and LCP beams varies to ±4ns. The superposing structured vectors field of superluminal and subluminal circularly polarized light beams on the right and left ER,L(r,φ) are strong variation function of detuning of probe field δ/Γ, Rabi frequency of control field Λ3/Γ and phase of collective driving fields φ. The results are useful for the modification of powerful computers.

The number of critical points of a Gaussian field: finiteness of moments

The number of critical points of a Gaussian field: finiteness of moments

Структура вихревых полей в волноводе пекериса с учетом дислокаций

Vortex fields are the most complex and least studied objects in the acoustics of layered media. They significantly complicate the structure of the sound field due to the appearance of nodal and saddle points in it, in the vicinity of which the concept of the phase of the sound wave becomes uncertain. Therefore, such special points of the sound field are usually called phase front dislocations. In turn, the dislocation structure of the vortex field is most complex in waveguides, which play an extremely important role in theoretical and applied hydroacoustics. In this work, the vortex structure of the sound field and the corresponding dislocation structure of the vortex field are analyzed using the example of a Pekeris waveguide, the sound field in which is constructed within the framework of a non-self-adjoint model formulation of the corresponding boundary value problem.

Magnetic-field oscillation model of pulsar radio emission: prediction of an observable effect

Abstract Since the discovery of pulsars, the rotating-lighthouse model has been the choice of model to explain the radiation pulsation of pulsars. After discovering that some main sequence stars (e.g. CU Virginis) and ultracool dwarfs (e.g. TVLM 513-46546) also behave like pulsars, the lighthouse model was again adopted to explain their pulse signals. Our research found that if we use the magnetic-field oscillation (MO) model, we can explain the pulse radiation results better regardless of whether its source is a neutron star, a main-sequence star or an ultracool dwarf. We propose a verifiable prediction that can be used to evaluate the MO model. Our prediction is that there is a 90○ phase lag between the magnetic field and radio signal of TVLM 513-46546, and the zero-crossing point of the magnetic field is the moment when the direction of the light’s circular polarization is reversed. No new observations are needed to check this prediction, but certain existing data needs to be re-mined.

A Microfluidic Chip for Single-Cell Capture Based on Stagnation Point Flow and Boundary Effects.

The capture of individual cells using microfluidic chips represents a widely adopted and efficient approach for investigating the biochemical microenvironment of singular cells. While conventional methods reliant on boundary effects pose challenges in precisely manipulating individual cells, single-cell capture grounded in the principle of stagnation point flow offers a solution to this limitation. Nevertheless, such capture mechanisms encounter inconsistency due to the instability of the flow field and stagnation point. In this study, a microfluidic device for the stable capture of single cells was designed, integrating the principle of fluid mechanics by amalgamating stagnation point flow and boundary effects. This innovative microfluidic chip transcended the limitations associated with single methodologies, leveraging the strengths of both stagnation point flow and boundary effects to achieve reliable single-cell capture. Notably, the incorporation of capture ports at the stagnation point not only harnessed boundary effects but also enhanced capture efficiency significantly, elevating it from 31.9% to 83.3%, thereby augmenting capture stability. Furthermore, computational simulations demonstrated the efficacy of the capture ports in entrapping particles of varying diameters, including 9 μm, 14 μm, and 18 μm. Experiment validation underscored the capability of this microfluidic system to capture single cells within the chip, maintaining stability even under flow rate perturbations spanning from 60 μL/min to 120 μL/min. Consequently, cells with dimensions between 8 μm and 12 μm can be reliably captured. The designed microfluidic system not only furnishes a straightforward and efficient experimental platform but also holds promise for facilitating deeper investigations into the intricate interplay between individual cells and their surrounding microenvironment.

Bridge-Borne Noise Induced by High-Speed Freight Electric Multiple Units: Characteristics, Mechanisms and Control Measures

The high-speed freight electric multiple unit (EMU) is one of the important development directions for railway freight transportation. To investigate the bridge radiation noise induced by the freight EMU, a noise prediction model consisting of the containers–vehicle–track–bridge dynamic model, finite element model, and boundary element model are established and validated. Through simulation, the bridge radiation noise under different train loading conditions is compared, and the noise radiation mechanism is revealed. Moreover, the noise reduction effect of the noise wall is studied, and the influences of noise wall heights and sound absorption materials are investigated. Results indicate that the bridge sound power and the sound pressure levels (SPLs) of near-field points increase slightly with train loads in the frequency range below 20 Hz and above 125 Hz, with a maximum increase of about 6.8 dB. The structure resonance, intense local vibration, and high acoustic radiation efficiency cause strong bridge radiation noise. The noise wall can realize a good overall noise reduction effect in the sound shadow zone; nevertheless, SPLs increased in areas between the bridge and the noise wall. The ground reflection affects the superposition of transmitted, reflected, and diffracted sound waves, which causes nonlinear relationships of noise reduction effects with the noise wall height. From the perspective of human hearing sensitivity, the loudness levels of typical field points increase with the frequency in the range of 20~80 Hz, and SPLs below 25 Hz are less than the threshold of hearing. Setting the noise wall can effectively reduce the loudness levels, and the reduction effect increases with the noise wall height.

Advances in layered transition metal oxide cathodes for sodium-ion batteries

The rapid rise of renewable energy technology has greatly promoted the development of energy storage systems. Breaking decades of stagnation, sodium-ion batteries (SIBs) have now regained momentum in the field of energy storage and they are considered as a low-cost alternative to lithium-ion batteries. The search for suitable materials to reversibly host sodium ions has become a focal point in SIB field. Layered transition metal oxide (NaxTMO2) as the cathode material has attracted increasing attention due to its simple structure, facile synthesis, and high operating potential. Nevertheless, NaxTMO2 still faces severe challenges, including irreversible phase transitions, storage instability, insufficient performance, etc. This work provides a comprehensive review of NaxTMO2 as the cathode material for SIBs, analyzes the challenges encountered by NaxTMO2, and summarizes effective improvement strategies. Strategies including doping, composite cathode materials, high-entropy materials and microstructural modulation can effectively guide the design of NaxTMO2 with excellent performance. SIBs are bound to play a positive role in the new round of energy revolution.

Visual outcomes in tuberculum sellae meningiomas comparing transcranial and endoscopic endonasal approaches

Tuberculum sellae meningiomas (TSM) account for 3-10% of intracranial meningiomas. Visual loss is the presenting symptom in up to 80% of cases. Surgical management poses a great challenge due to tumor proximity to neurovascular structures such as the optic nerve and the internal carotid artery (ICA); hence, there is controversy regarding the optimal approach. The aim of this study is to determine differences in visual outcomes between transcranial (TCA) and endoscopic endonasal (EEA) approaches. A retrospective study including 29 patients with TSM surgically treated by TCA or EEA between 2011 and 2023 in a single referral center was conducted. Pre-and post-operative neuro-ophthalmologic evaluations, focusing on visual acuity and campimetry, were evaluated. Sixteen (55.16%) patients were intervened through a TCA and the remaining 13 (44.84%) via an EEA. The lesions in each group were similar in terms of pre- operative volume (15.12 vs 12.9cm3, p=0.497) and neurovascular invasion (optic canal invasion 48.26 vs 41.37%, p=0.664; ICA 44.81 vs 31.03%, p=0.797). There were no significant differences in visual outcomes between both approaches; TCA presented an improvement of 5.18 points in visual fields (p=0.140), whereas EEA had an improvement of 17.39 points in visual acuity (p=0.114). EEA seems to offer greater improvement in visual acuity than TCA. However, the ideal approach should be individualized; taking into account the tumor's volume and invasiveness, as well as the patient's visual complaints.

Distortion measurement of a lithography projection lens based on multichannel grating lateral shearing interferometry.

The optical distortion of the lithographic projection lens can reduce imaging quality and cause overlay errors in lithography, thus preventing the miniaturization of printed patterns. In this paper, we propose a technique to measure the optical distortion of a lithographic projection lens by sensing the wavefront aberrations of the lens. A multichannel dual-grating lateral shearing interferometer is used to measure the wavefront aberrations at several field points in the pupil plane simultaneously. Then, the distortion at these field points is derived according to the proportional relationship between the Z 2 and Z 3 Zernike terms (the tilt terms) and the image position shifts. Without the need for additional devices, our approach can simultaneously retrieve both the wavefront aberrations and the image distortion information. Consequently, it improves not only measurement speed and accuracy but also enables accounting for displacement stage positioning error. Experiments were conducted on a lithographic projection lens with a numerical aperture of 0.57 to verify the feasibility of the proposed method.

Methodical ways of studying proper names in professional discourse while teaching a foreign language to the students of agrarian universities

This article considers the effectiveness of using proper names in teaching a professional foreign language English for Specific Purposes (ESP) to students of various agricultural specialties. In modern studying programs, almost no attention is paid to the study of the proper name, which occupies an essential place in the vocabulary of any language, reflecting important aspects of its history and culture development. Onomastics as a specific branch of linguistics has been formed at the cross point of several fields. The achievements of the regional onomastics determine the source of information relevant for foreign language teachers at the agrarian Universities. The study of writing and culture relicts, data from etymological dictionaries, local history and literature, research of groups of zoonyms, toponyms and anthroponyms determine the necessity of developing and applying new methodological techniques and technologies. All of the above determines the relevance of this article’s topic and defines its goals: to consider the effectiveness of using proper names when learning a foreign language applicable in professional activities; to present effective methodological techniques that contribute to the development of professional competencies. In preparing this article, such methods of scientific analysis and generalization were applied as descriptive, methods of etymological analysis, as well as elements of comparative and typological analysis.

Trajectory Interception Classification for Prediction of Collision Scope between Moving Objects

In the fields of autonomous navigation and vehicle safety, accurately predicting potential collision field points between moving objects is a significant challenge. A novel computing technique to enhance trajectory interception analysis is presented in this paper. Our objective is to develop a field model that can accurately forecast collision zones, improving road transportation safety and the use of autonomous cars. Our main contribution is a binary classification model called PCSMO (Prediction of Collision Scope between Moving Objects), which is based on zero-shot learning. Gann angles, which are typically 45 degrees, are used to analyze the trajectories of moving objects. This method is inspired by GANN (Gann Angle Numeric Nomenclature). Compared to earlier techniques, this model more accurately identifies potential collision collision interception zones. The technique computes Gann angles for trajectory analysis and extracts GPS coordinates of moving objects from video data using OpenCV. It offers a more sophisticated comprehension of object movement patterns and points of interception. To assess the precision, recall, F1-score, and prediction accuracy of our model, we employ 10-fold cross-validation. Comparing the PCSMO model to existing models, these metrics demonstrate how well the PCSMO model predicts potential collision zones. Our approach, we discovered, enhances trajectory analysis—a critical component of safer autonomous navigation systems. With potential applications in autonomous vehicle and UAV safety, the PCSMO model improves field interception classification.

The Method of Images Revisited: Approximate Solutions in Wedge‐Shaped Aquifers of Arbitrary Angle

AbstractThis paper focuses on deriving new approximate analytical solutions in wedge‐shaped aquifers. The proposed methodology is applicable to any type of aquifer namely, leaky, confined and unconfined, under both steady state and transient flow conditions. By applying the method of images and separating the flow field into sections using physical arguments, approximate analytical expressions are obtained for the drawdown function, which in contrast to the conventional theory, are applicable to any arbitrary wedge angle. Moreover, the solutions fully observe the boundary conditions, while they preserve the continuity of the drawdown, which can be calculated directly at any point of the flow field. Nevertheless, comparison of the results of the new approximate analytical solutions to numerical ones, has been considered necessary to check their validity. MODFLOW, a well‐known numerical tool is used to calculate the numerical results. The discrepancies between the numerical results and those of the approximate analytical solution are negligible. The main advantages of the proposed methodology are the following: (a) The model needs only finite number of terms compared to conventional analytical and numerical solutions that involve infinite series, (b) The computational load is low, so it can be easily used in conjunction with meta‐heuristic algorithms to solve groundwater resources optimization problems, (c) Stream depletion rate can be calculated rather accurately and (d) The method is applicable to related flow problems.

Accuracy Assessment of Land Use/Land Cover Indices for Al-Rusafa in Baghdad Governorate by Remote Sensing Technology and GIS

The management and planning of natural and artificial resources depend on accurately monitoring land cover changes. Land cover change mapping and monitoring used to require expensive field surveys. Remote sensing is cheaper and more practical for mapping land use and cover changes. The Tigris River divides the Iraqi capital, Baghdad, into two parts: Karkh and Rusafa. Al-Rusafa was selected as a study area for current research, which has had rapid population and urban growth in recent decades. The current research applies the support vector machine technique to supervised LU/LC maps’ classification into barren regions, water bodies, vegetation cover and built-up regions. Spectral indicators were calculated: Enhanced Vegetation Index, Modified Normalized Difference Water Index, Normalized Built-Up Area Index, Dry Bareness Index in addition to calculating the accuracy assessment and Kappa coefficient. Using the Landsat 9 satellite image, ArcGIS 10.8 and Envi5.3 software were used to analyze and evaluate the results and field points observed by GPS devices. The results showed that the SVM classification algorithm accurately revealed the categories of LU/LC, where the classification accuracy reached 95%, and that the arid lands covered most of the study area 848.864 km2 and water bodies 76.747 km2, the vegetation and the built-up regions 466.459 km2 and 439.077 km2, respectively. The spectral indices showed slightly different areas of barren lands (DBSI 752.589 km2, 93% accuracy), vegetation (EVI 423.651 km2, 96% accuracy), and water bodies (MNDWI 73.187 km2, 98% accuracy) and built-up areas (NBAI 501,731 km2, 90%accuracy). The Support Vector Machine method outperforms other classification methods, and the spectral indicators employed in this work are useful and dependable for extracting each LU/LC category. In conclusion, Landsat 9 satellite data can reliably and swiftly detect ground cover.

The Status Quo of Pharmacogenomics of Tyrosine Kinase Inhibitors in Precision Oncology: A Bibliometric Analysis of the Literature.

Precision oncology and pharmacogenomics (PGx) intersect in their overarching goal to institute the right treatment for the right patient. However, the translation of these innovations into clinical practice is still lagging behind. Therefore, this study aimed to analyze the current state of research and to predict the future directions of applied PGx in the field of precision oncology as represented by the targeted therapy class of tyrosine kinase inhibitors (TKIs). Advanced bibliometric and scientometric analyses of the literature were performed. The Scopus database was used for the search, and articles published between 2001 and 2023 were extracted. Information about productivity, citations, cluster analysis, keyword co-occurrence, trend topics, and thematic evolution were generated. A total of 448 research articles were included in this analysis. A burst of scholarly activity in the field was noted by the year 2005, peaking in 2017, followed by a remarkable decline to date. Research in the field was hallmarked by consistent and impactful international collaboration, with the US leading in terms of most prolific country, institutions, and total link strength. Thematic evolution in the field points in the direction of more specialized studies on applied pharmacokinetics of available and novel TKIs, particularly for the treatment of lung and breast cancers. Our results delineate a significant advancement in the field of PGx in precision oncology. Notwithstanding the practical challenges to these applications at the point of care, further research, standardization, infrastructure development, and informed policymaking are urgently needed to ensure widespread adoption of PGx.

High-precision analysis of aberration contribution of Zernike freeform surface terms for non-zero field of view.

Clarifying the aberrations arising from freeform surfaces is of great significance for maximizing the potential of freeform surfaces in the design of optical systems. However, the current precision in calculating aberration contribution of freeform surface terms for non-zero field of view is insufficient, impeding the development of freeform imaging systems with larger field of view. This paper proposes a high-precision analysis of aberration contribution of freeform surface terms based on nodal aberration theory, particularly for non-zero field points. Accurate calculation formulas of aberrations generated by Zernike terms on freeform surface are presented. Design examples illustrate that the calculation error of the provided formulas is 78% less than that of conventional theoretical values. Building upon high-precision analysis, we propose an optimization method for off-axis freeform surface systems and illustrate its effectiveness through the optimization of an off-axis three-mirror system. This research extends the applicability of nodal aberration theory in aberration analysis, offering valuable insights for the optimal design and alignment of optical freeform systems.