Precise Gap Research Articles

Novel identification algorithm for plasma boundary gap based on visible endoscope diagnostic on EAST tokamak

The precise plasma boundary gap identification at the midplane is a prerequisite for achieving controlled plasma positioning and holds a significant importance for the stable operation of tokamak devices. This study proposes a plasma boundary gap at the midplane recognition algorithm based on visual endoscopy diagnostic. The model is an end-to-end one that uses a convolutional neural network that does not require manual data labeling. The model performance is improved by experimentally comparing different convolutional layers and input image sizes. The model is validated using a testing dataset comprising 400 plasma discharge moments. The model has average errors of 3.7 and 4 mm for gap-in and -out, respectively, when compared to those obtained by equilibrium fitting. The proposed approach offers a convenient and effective means of obtaining the boundary gap value and is particularly suited for future fusion experimental devices, such as BEST and ITER tokamak.

Dynamic hysteresis effects

We study how the output gap affects potential output over time—i.e., the dynamic hysteresis effect. To do so, we introduce novel unobserved components (UC) models that consider hysteresis as a sequence of lagged effects, thus separating the long-run recession-induced adverse effects from other trend-cycle interactions. The proposed models nest several existing UC models in the literature and accommodate two key characteristics of output dynamics: non-neutrality in the long-run and time-to-build effects. Using Bayesian estimation methods, we find robust evidence supporting the presence of hysteresis effects after the 1970s, with the negative long-run effect of the Global Financial Crisis and the COVID-19 recessions robustly identified. Via Bayesian model averaging, we provide precise and intuitive output gap estimates that highlight the relationship between business cycle fluctuations and the decline in economic growth. Our findings indicate that output trend-cycle decompositions that do not consider hysteresis effects can alter stabilization policy trade-offs.

Comparative study of the adaptation of alkasite versus self-adhesive flowable restorations

Aim To compare the adaptation of self-adhesive flowable composite versus alkasite restorations with or without the use of an adhesive system. Materials and Methods A total of 30 noncarious maxillary premolars were selected and mounted 2 mm below the cemento–enamel junction in acrylic blocks. Trapezoidal class V cavities were prepared on the buccal surface of each tooth. The gingival margins of the prepared cavities were located 1 mm above cemento–enamel junction. All cavity margins were not bevelled. During the experiment time, all samples were kept in artificial saliva renewed daily at 37°C in an incubator to prevent dehydration. These were randomly divided into three groups (n = 10). Alkasite restorative material was applied in a bulk fill technique using a universal adhesive in samples of group I, while those of group II did not have any adhesive using the same restorative material and those of group III were restored using self-adhesive flowable composite (vertise flow). Specimens of the three tested groups were subjected to 500 thermal cycles from 5 to 55°C with 30 s. Dwell time and 15 s transfer time. They were all immersed in methylene blue dye 2% for 24 h in an incubator. Then all samples were examined under stereomicroscopy at ×40 to determine the percentage of gap free length along the entire margins. All specimens were then sectioned buccolingually to detect the percentage of internal gap length along the restoration/tooth interface. Results Regarding the marginal adaptation, the highest % of marginal free gap was recorded for group I, while the lowest was recorded for group II. Concerning the internal adaptation, it was found that the highest % of free gap was related to group I and III while the lowest was related to group II. Comparing the marginal versus internal % of gap free margins it was found that group I versus II showed a statistically significant difference. Also, group III versus II showed a significant difference. While group I versus III recorded no statistically significant difference. This was true at both marginal and internal % of free gaps. These findings indicated the responsibility of group II for the recorded differences since group II showed the least % of free gap margins and the highest percentage of total dye penetration values. Conclusions Within the limitations of this in vitro study, the adhesive system was effective in increasing the percentage of free gaps of tested groups whether marginal or internal. Recommendations The use of any composite material is not recommended without an adhesive system. Further in vitro studies providing more precise gap measurement are required.

Exploring aspect-based sentiment quadruple extraction with implicit aspects, opinions, and ChatGPT: a comprehensive survey

In contrast to earlier ABSA studies primarily concentrating on individual sentiment components, recent research has ventured into more complex ABSA tasks encompassing multiple elements, including pair, triplet, and quadruple sentiment analysis. Quadruple sentiment analysis, also called aspect-category-opinion-sentiment quadruple Extraction (ACOSQE), aims to dissect aspect terms, aspect categories, opinion terms, and sentiment polarities while considering implicit sentiment within sentences. Nonetheless, a comprehensive overview of ACOSQE and its corresponding solutions is currently lacking. This is the precise gap that our survey seeks to address. To be more precise, we systematically reclassify all subtasks of ABSA, reorganizing existing research from the perspective of the involved sentiment elements, with a primary focus on the latest advancements in the ACOSQE task. Regarding solutions, our survey offers a comprehensive summary of the state-of-the-art utilization of language models within the ACOSQE task. Additionally, we explore the application of ChatGPT in sentiment analysis. Finally, we review emerging trends and discuss the challenges, providing insights into potential future directions for ACOSQE within the broader context of ABSA.

The Bessel kernel determinant on large intervals and Birkhoff's ergodic theorem

AbstractThe Bessel process models the local eigenvalue statistics near 0 of certain large positive definite matrices. In this work, we consider the probability where and is any non‐negative integer. We obtain asymptotics for this probability as the size of the intervals becomes large, up to and including the oscillations of order 1. In these asymptotics, the most intricate term is a one‐dimensional integral along a linear flow on a g‐dimensional torus, whose integrand involves ratios of Riemann θ‐functions associated to a genus g Riemann surface. We simplify this integral in two generic cases: (a) If the flow is ergodic, we compute the leading term in the asymptotics of this integral explicitly using Birkhoff's ergodic theorem. (b) If the linear flow has certain “good Diophantine properties”, we obtain improved estimates on the error term in the asymptotics of this integral. In the case when the flow is both ergodic and has “good Diophantine properties” (which is always the case for , and “almost always” the case for ), these results can be combined, yielding particularly precise and explicit large gap asymptotics.

Novel technique in detecting marginal adaptation of all ceramic restoration after cementation: case report

BackgroundAccurate marginal adaptation of dental restorations guarantees their long-term success and longevity. Clinical evaluation of marginal adaptation is done using different techniques utilizing conventional tools such as mirrors and probes, which are subjective and non-standardized. Precise determination of restorations marginal gap intraorally, represents a challenge, especially when conducting clinical research testing newly introduced restoration designs or materials.Case presentationA 31-years-old female patient came to dental clinic seeking full coverage restoration for an endodontically treated upper left maxillary first premolar. After the patient received an all ceramic Bruxzir crown, the marginal adaptation and precise gap determination were evaluated intraorally utilizing digital microscope, aided with a novel custom-made microscope-holding device that facilitated standardization and handling.ConclusionsThe described method aided with the novel custom-made microscope holding device proved to be an easy, time saving and precise technique in evaluating the marginal gap directly inside patient’s mouth especially in clinical researches.

Full Control of Plasmonic Nanocavities Using Gold Decahedra-on-Mirror Constructs with Monodisperse Facets.

Bottom-up assembly of nanoparticle-on-mirror (NPoM) nanocavities enables precise inter-metal gap control down to ≈ 0.4nm for confining light to sub-nanometer scales, thereby opening opportunities for developing innovative nanophotonic devices. However limited understanding, prediction, and optimization of light coupling and the difficulty of controlling nanoparticle facet shapes restricts the use of such building blocks. Here, an ultraprecise symmetry-breaking plasmonic nanocavity based on gold nanodecahedra is presented, to form the nanodecahedron-on-mirror (NDoM) which shows highly consistent cavity modes and fields. By characterizing >20000 individual NDoMs, the variability of light in/output coupling is thoroughly explored and a set of robust higher-order plasmonic whispering gallery modes uniquely localized at the edges of the triangular facet in contact with the metallic substrate is found. Assisted by quasinormal mode simulations, systematic elaboration of NDoMs is proposed to give nanocavities with near hundred-fold enhanced radiative efficiencies. Such systematically designed and precisely-assembled metallic nanocavities will find broad application in nanophotonic devices, optomechanics, and surface science.

A new measure of the output gap, inflation dynamics, and the New Keynesian Phillips Curve

Literature suggests that measures of slack such as unemployment, output, labour share, and inflation have been separated in recent years, particularly after the global crisis. Some claimed that the Phillips curve had vanished. Because of the unobservable nature of the natural rates, estimation of the output and unemployment gaps might not offer precise outcomes. The inflation model permits a fraction of firms that use a backwards-looking rule to set prices, as Gali and Gertler (2000) did. The essential contrast between their paper and mine is that they utilized marginal cost estimates as the applicable determinant of inflation, and I utilized the estimated output gap. Gali and Gertler supposed real marginal costs are a significant determinant of inflation. They also believed the output gap was negative and inconsequential. I have indicated that a precise output gap estimate is significant and positive. CBO output gap is also used to inspect for robustness. However, it was also insignificant, as the literature suggests. Therefore, the model used the estimated output gap instead of marginal cost. I calculated the output gap with a new methodology and could replicate their results with the new measure. I extended their study to 2019Q4; It is showed that their measure for inflation slack which was marginal cost becomes insignificant; however, my measure of the output gap is still significant. Therefore, it was inferred that the New Keynesian Phillips curve reasonably still explains inflation dynamics. I also concluded that the hybrid new Keynesian Phillips curve might explain the inflation dynamics.

Prospects of charge signal analyses in liquid xenon TPCs with proportional scintillation in the liquid phase

As liquid xenon TPCs increase in target mass while pursuing the direct detection of WIMP dark matter, the technical challenges arising due to their size call for new solutions and open the discussion on alternative detector concepts. Proportional scintillation in liquid xenon allows for a single-phase design evading problems related to the liquid-gas interface and the precise gas gap required in a dual-phase TPC.Aside from a different scintillation mechanism, the successful detection- and analysis scheme of state-of-the-art experiments is maintained in this approach.We study the impact on charge signal analysis in a single-phase detector of DARWIN dimensions, where the fast timing of the proportional scintillation signal allows for the precise identification of the single electrons in the ionisation signal.Such a discrete electron-counting approach can lead to a better signal resolution for low energies when compared to the classical dual-phase continuous method.The absence of the liquid-gas interface can further benefit the S2-only energy resolution significantly. This can reduce the uncertainties from the scintillation and signal-detection process to a level significantly below the irreducible fluctuation in the primary ionisation. Exploiting the precise electron arrival time information can further allow for a powerful single vs. multiple site interaction discrimination with 93% rejection efficiency and 98% signal acceptance. This outperforms the design goal of the DARWIN observatory by a reduction factor of 4.2 in non-rejected multiple site neutron events.

Asymptotic expansion and optimal symmetry of minimal gradient graph equations in dimension 2

In this paper, we study asymptotic expansion at infinity and symmetry of zero mean curvature equations of gradient graph in dimension 2, which include the Monge–Ampère equation, inverse harmonic Hessian equation and the special Lagrangian equation. This refines the research of asymptotic behavior, gives the precise gap between exterior minimal gradient graph and the entire case, and extends the classification results of Monge–Ampère equations.

Asymptotic Expansion at Infinity of Solutions of Special Lagrangian Equations

We obtain a quantitative high order expansion at infinity of solutions for a family of fully nonlinear elliptic equations on exterior domain, refine the study of the asymptotic behavior of the Monge-Amp\`ere equation, the special Lagrangian equation and other elliptic equations, and give the precise gap between exterior maximal (or minimal) gradient graph and the entire case.

Computational fluid dynamic modelling of supersonic ejectors: comparison between 2D and 3D modelling

It is known that the global performances of ejector-based systems (viz., at the “global-scale”) depend on the local flow properties within the ejector (viz., at the “local-scale”). For this reason, reliable computational fluid-dynamics (CFD) approaches, to obtain a precise and an a-priori knowledge of the local flow phenomena, are of fundamental importance to support the deployment of innovative ejector-based systems. This communication contributes to the existing discussion by presenting a numerical study of the turbulent compressible flow in a supersonic ejector. In particular, this communication focuses on a precise knowledge gap: the comparison between 2D and 3D modelling approaches as well as density-based and pressure-based solvers. The different approaches have been compared and validated against literature data consisting in entrainment ratio and wall static pressure measurements. In conclusion, this paper is intended to provide guidelines for researchers dealing with the numerical simulation of ejectors.

Assessment of diagnostic reference levels awareness and knowledge amongst CT radiographers

BackgroundReports indicated that numerous factors, including inadequate personnel knowledge, contributes to insufficient patient data for setting up diagnostic reference levels (DRLs) in developing countries. This study aims to evaluate the knowledge of DRLs as an optimisation tool amongst computed tomography (CT) radiographers in northern Nigeria. This is a quantitative cross-sectional study. A structured questionnaire was devised and distributed on site to sixty-two CT radiographers in northern Nigeria. A total of fifteen questions were included in the questionnaire focusing on DRLs, dose optimisation and dose descriptors generating quantitative data concerning overall CT radiographers’ perceived knowledge and awareness about DRLs.ResultsA response rate of 77.4% (48/62) was achieved. About 83.3% of the participants declare DRLs awareness, and 37.5% carried out a local dose survey. The percentage correctly perceived knowledge of concepts; DRLs was 45.8%, dose optimisation (42%) and CT dose descriptor (39%). Radiographers with work experience ranging from 4-10 years had the highest score.ConclusionIn this survey, deficiencies were noted in radiographers’ knowledge about DRLs with precise knowledge gap in the implementation of local dose survey for DRLs and optimisation. There is a need for continuous radiographers’ training with greater emphasis on dose optimisation and institutional based dose evaluation.

The medial gap is a reliable indicator for intraoperative soft tissue balancing in posterior-stabilized total knee arthroplasty

BackgroundAppropriate soft tissue balance and accurate alignment are important for successful total knee arthroplasty (TKA). However, the optimal technique for establishing and measuring soft tissue balancing remains unclear. The aim of this study was to analyze the intraoperative medial and lateral gap pattern using digital knee balancer in posterior-stabilized (PS) TKA. MethodsThis study involved 55 patients with medial osteoarthritis who underwent a primary TKA using an image-free navigation system. The extension gap and the flexion gap at 90° knee flexion were assessed using an offset seesaw-type digital balancer. Continuous joint distraction force from 10 lb to 60 lb was applied. Medial gap, lateral gap, and varus angle were measured. ResultsThe medial bone gap difference between extension and flexion was constant regardless of the distraction force from 20 lb to 60 lb. The lateral bone gap was significantly greater than the medial bone gap in extension and flexion from 30 lb to 60 lb (P < 0.05). The varus angle changed depending on the distraction force, especially in flexion. The varus angle in flexion was significantly greater than that in extension from 40 lb to 60 lb (P < 0.05). ConclusionsThe medial bone gap is a reliable indicator unaffected by the distraction force during surgery and is useful for adjusting the medial gap in extension and flexion appropriately to ensure medial stability in PS-TKA. The digital knee balancer and navigation system support both precise gap assessment and surgery.

Seller experience assessment in online marketplace: a scale development study

PurposeRecent decade has witnessed exponential growth in e-commerce segment, leading to emergence of various online selling platforms catering to diverse product requirements of customers. Such a development has provided impetus to both existing businesses and newly established ventures to make available their offerings through online selling platforms with a view to improve the reach of their products. This study is an attempt to identify the experience of registered vendors with the online marketplaces. It aims to develop and validate a scale to measure vendor's experience with e-commerce platforms.Design/methodology/approachAs a part of the scale development process, relevant literature sources were scanned to spot the precise knowledge gap and to put in place a sound theoretical background for the study. Thereafter, a scientific approach was adopted for scale creation. First, the scale items were identified through interviews of vendors registered with major online selling platforms and other academic experts pertaining to the marketing domain. Subsequently, major dimensions of seller experience were identified through exploratory factor analysis (EFA) applied on data collected from active vendors by the means of a structured survey instrument. The final data set was subjected to confirmatory factor analysis (CFA) in a bid to validate the scale.FindingsThe study’s outcomes reveal that seller experience in an online marketplace can be best captured by a multidimensional scale characterized by six major dimensions. These are “Registration,”; “Product Listing”; “Pricing Autonomy”; “Ease of Pick-up and Delivery”; “Credit of Receivables” and “Vendor Assistance.” A proper emphasis to continually improve upon these dimensions by the e-commerce platforms is expected to enhance the utility and overall experience of vendors from such platforms. Existence of a mutually beneficial relationship between vendors and online marketplaces will help marketplaces to mitigate concerns like nonfulfillment of orders and dispatch of substandard products.Originality/valueSustainable long-term relations between vendors and online marketplaces hold the key for such marketplaces to render error-free and delightful service on each individual order received. Seller experience of registering and operating on such e-marketplaces inspite of playing a defining role in vendor–marketplace relations has received scant attention of researchers, both in academia and industry till date. The present research is a seminal attempt to address this gap in marketing literature and offer additional know-how.

Control and Operation of a Hybrid Actuator for Maglev Applications

Abstract The hybrid actuator presented in this article is meant to enable stationary and slow dynamic levitation in Maglev applications. The term ‘hybrid’ refers to the design of the actuator, which is a combination of permanent magnets (PM) and electromagnets. This paper presents an analytically computable control algorithm for the said hybrid actuator. The theory of magnetic circuits is summarized shortly and used to derive a cascaded control loop consisting of an inner current controller and an outer air gap controller. Since the uncontrolled hybrid actuator is inherently unstable, the system has to be stabilized. By introducing a PID-controller into the air gap control loop, the unstable behaviour of the uncontrolled system is changed into the system behaviour of a damped harmonic oscillator. The advantage of this approach is that the computed controller parameters of the PID-controller can easily be adjusted, so the system behaviour of damping and eigenfrequency can be selected within a certain range. For the execution of the control algorithm, a microcontroller (MCU) is used and for precise air gap measurement, an eddy current sensor is installed. Finally, the behaviour of the current- and air gap controller is discussed for different measurement results and the adjustable system behaviour of the damped harmonic oscillator is presented.

Analysis and Prediction of Gap Dynamics in a Secondary Deciduous Broadleaf Forest of Central Japan Using Airborne Multi-LiDAR Observations

Gaps are important for growth of vegetation on the forest floor. However, monitoring of gaps in large areas is difficult. Airborne light detection and ranging (LiDAR) data make precise gap mapping possible. We formulated a method to describe changes in gaps by time-series tracking of gap area changes using three digital canopy height models (DCHMs) based on LiDAR data collected in 2005, 2011, and 2016 over secondary deciduous broadleaf forest. We generated a mask that covered merging or splitting of gaps in the three DCHMs and allowed us to identify their spatiotemporal relationships. One-fifth of gaps merged with adjacent gaps or split into several gaps between 2005 and 2016. Gap shrinkage showed a strong linear correlation with gap area in 2005, via lateral growth of gap-edge trees between 2005 and 2016, as modeled by a linear regression analysis. New gaps that emerged between 2005 and 2011 shrank faster than gaps present in 2005. A statistical model to predict gap lifespan was developed and gap lifespan was mapped using data from 2005 and 2016. Predicted gap lifespan decreased greatly due to shrinkage and splitting of gaps between 2005 and 2016.

Analog LCOS SLM devices for AR display applications

AbstractLiquid crystal on silicon (LCOS) device is a potential candidate for spatial light modulators (SLMs) due to its high resolution and the wide range of tunable phase retardation. Besides the telecom applications, SLM is also very promising for display applications, especially for the augmented reality (AR) displays. In this paper, we will discuss the advantages of analog LCOS SLM compared with the digital one. A 0.6‐in short‐loop sample test result with precise cell gap controlled is discussed. A fast liquid crystal with high birefringence that attains less than 2.5‐ms full‐on–full‐off response time is also introduced. Regarding the computer‐generated hologram (CGH), a new algorithm called multiconstraints angular spectrum algorithm (MASA) is proposed to enhance the image quality of dual‐plane holographic projection.

Nonlinear plasmonic metasurfaces assisted laser mode locking

Plasmonic metasurfaces are artificial 2D layers made of subwavelength elementary cells, which give rise to novel wave properties that do not exist in nature. In the linear regime, their applications have been extensively studied, especially in wavefront manipulation for lensing, holography or polarization control. Interests in metasurfaces operating in nonlinear regime have also increased due to their ability to efficiently convert the fundamental light into harmonic frequencies and multiphoton emissions. Nevertheless, practical applications in the nonlinear regime have been rarely reported. In this study, we report that plasmonic metasurfaces with well-controlled polarimetric nonlinear transfer functions perform as saturable absorbers with modulation performances superior to that of other 2D materials. We employ planar nanotechnologies to fabricate 2D plasmonic metasurfaces with precise size, gap and orientation. We quantify the relationship between saturable absorption and the plasmonic resonances of the unit cell by altering the excitation power of pumping laser, the polarization of incident light and the geometrical parameters of the plasmonic metasurfaces. Finally, we provide a practical implementation by integrating the saturable metasurfaces into a fiber laser cavity and realize a stable self-starting ultrashort laser pulse generation. As such, this work sheds light on ultrathin nonlinear saturable absorbers for applications where nonlinear functions are required, such as in ultrafast laser or neuromorphic circuits.

A Study on Active Closed-Loop Gap Control for Hydrostatic Bearing

In this paper, a hydrostatic bearing controlled by servo-valve for precise closed-loop oil-film gap control is developed. Due to the increasing demands of larger dimension, heavier load and higher precision for current and future machine tools, the development of hydrostatic bearing has become a more and more important issue over the past decades. Nowadays, the most commonly used active pressure feedback restrictor for hydrostatic bearing is membrane type, in which a thin and flexible metal sheet serves as the key component to meter the hydraulic oil flow precisely. However, the membrane type pressure feedback restrictor is not quite suitable for extremely heavy load. Therefore, an alternative to design the active restrictor for hydrostatic bearing using servo-valve is presented in this paper. Different controllers are also designed and compared in this paper. There are two significant features regarding the proposed design. The first one is the introduced orifice restrictor inside the servo-valve which avoids the influence of possible oil temperature variation. The second feature is the introduced closed-loop oil-film gap control scheme that widens the application range effectively. Finally, a test rig of servo-valve controlled hydrostatic bearing is implemented and the experimental results prove the validity of the hydrostatic bearing with the proposed servo-valve and the closed-loop gap control scheme.