Height Of Point Research Articles

Thermal Characteristics of the Extreme Cases of Tropopause Over the Tropics

ABSTRACTThe anomalous variability of extreme cases of the tropical tropopause provides insight into the stratosphere‐troposphere exchange process crucial for understanding climate change. The present study analyses the extreme variability of the tropopause and its thermal structure over the tropics using GPS radio occultation data over the period 2006–2019. The extremely cold and warm tropopauses and extremely high and low tropopauses are identified based on the cold point tropopause temperature and height, respectively, when their values exceed two standard deviations with respect to their climatological means. The analyses revealed frequent occurrence of extreme cases of tropopause over the Atlantic Ocean compared to the Western Pacific Ocean. Individually, extremely warm and low cases occur more frequently over the subtropics, while extremely cold and high cases occur frequently over the deep tropics. These extreme cases pose different thermal structures bounded within the extremely low and high tropopauses throughout the tropics. The height difference between the extremely high and low tropopause cases is wider over the Atlantic Ocean and adjoining areas compared to the western Pacific Ocean. The temperature difference between the extremely warm and cold tropopause cases is higher in the Atlantic, Central Pacific, and Indonesian regions compared to the American, Indian Ocean, and western Pacific Ocean regions. The relationship between the El Niño Southern Oscillation (ENSO) phases and extreme tropopause cases is also investigated which reveals a higher occurrence of extremely high tropopause cases during the El Niño phase while low tropopause cases during the La Niña phase. Our analysis also revealed the thermal patterns of the extreme cases characterising colder and sharper tropopause over the convective regions compared to subsidence regions.

Comparison of UAV Orthophoto and Ground Survey at a Flood Protection Embankment

In the study, I compare the elevation data of points obtained from an orthophoto taken from a drone with the heights of points measured from the area by ground survey procedure and measuring station. I examine the usability of the points determined from the orthophoto for flood protection and for assessing flood protection embankments. I present the difficulties of assessing floodplains. The taking of orthophotographs and the data obtained from them may be important in determining the conditions after the floods have subsided and in detecting sediment deposition. My aim is to examine to what extent orthophotographs can be used to determine embankment heights in case of flooding, in order to avoid water overtopping of protective embankments.

Normal contact stiffness modeling and contact characteristic research of scraped surfaces considering the truncated cone high points

In order to study the normal contact characteristics of scraped surface, a normal contact stiffness model of scraped surface was proposed considering truncated cone high points, where scraped surface was equivalent as tandemly connected truncated cone high points with asperity. The high points parameters such as the percentage of high points (POP) and the height of high points (HOP) were obtained by lapping-image processing and high points height histogram, respectively. Through high points elastic deformation formula and fractal asperity elastic-plastic deformation formula, the normal contact stiffness model of scraped surface is established. Results show that increasing fractal dimension and reducing contact gap by lapping, while decreasing HOP and increasing POP by scraping can improve the contact characteristics of scraped surface.

Condylar Remodeling and Skeletal Changes Following Occlusal Splint and Manual Therapy: A Cone Beam Computed Tomography Study in Temporomandibular Disorders.

Background: Temporomandibular disorders (TMD) may be associated with degenerative disease of temporomandibular joint (TMJ), such as condyle erosion and subchondral cysts. Occlusal splint and cranio-mandibular manual therapy, or combined therapy, is recommended as a conservative treatment to alleviate pain-related signs and symptoms in TMD. This study aimed to assess osseous condylar changes and skeletal changes following occlusal splint and cranio-mandibular manual therapy in TMD using cone beam computed tomography (CBCT). Methods: A retrospective cohort study included 24 patients diagnosed with TMD. Combined therapy was performed until pain-related signs and symptoms disappeared. CBCT scans were performed before and after therapy. Osseous structure of condyles and their subsequent modifications were analyzed on CBCT images: flattening, erosion, and subchondral cyst. Sella-Nasion-A point (SNA), Sella-Nasion-B point (SNB), A point-Nasion-B point (ANB), Sella-Articulare-Gonion (Condylar angle), and anterior and posterior facial height (AFH, PFH) were measured on CBCT-generated lateral cephalograms. A paired t-test, Wilcoxon rank-sum test, McNemar test, and Stuart-Maxwell test were used for the statistical analyses. Results: The treatment period with combined therapy was 7.42 ± 3.27 months, and 21 out of 33 TMJ presenting degenerative disease (63.6%) had significant complete remodeling (p < 0.05). Following therapy, SNB significantly decreased from 75.61 ±3.47° to 74.82 ± 3.41° (p = 0.02), ANB significantly increased from 4.05° (3.35-4.9°) to 4.8° (3.3-6.12°) (p < 0.001), AFH significantly increased from 112.85 mm (109.28-118.72) to 115.3 mm (112.58-118.88) (p < 0.001), PFH/AFH significantly decreased from 64.17 (61.39-66.1) to 63 (59.68-64.51) (p = 0.012), and condylar angle significantly increased from 140.84 ± 8.18° to 144.42 ± 8.87° (p = 0.007). Conclusion: Combined therapy promoted significant condylar remodeling in TMJ degenerative disease, along with skeletal changes (mandibular retrusion and increase in facial height). Therapeutic strategies should consider condylar remodeling in TMD. Skeletal and dental parameters should be evaluated prior to occlusal splint therapy.

Scours effects on the lateral bearing capacity of monopile-friction wheel composite foundations in sand-overlaying-clay deposit

The monopile-friction wheel composite foundation is recognized as an innovative offshore wind turbines (OWTs) foundation type, distinguished by its superior lateral bearing capacity and resistance to local scouring. In order to investigate the influence of local scour in sand-overlaying-clay deposit on the lateral bearing capacity of this new type of composite foundations, a series of numerical simulations are conducted to explore the effects of potential parameters including different scour parameters, overlying sandy layer thickness and loading point height on the lateral bearing performance. The results indicate that the greatest reduction in lateral bearing capacity of the composite foundation due to scour depth can reach approximately 35%, while the scour extent and angle have relatively small effects. Moreover, the lateral bearing capacity of the composite foundation increases with the thickness of overlying sandy layer. Local scour and the sand layer thickness also affect the lateral deformation and the soil resistance along the pile shaft. Furthermore, as the loading point height increases, the lateral resistance of the composite foundation decreases rapidly. These findings offer valuable insights for the design of monopile-friction wheel composite foundations in sand-overlying-clay deposits.

Impact of fuel dilution on Lawson parameter by considering relativistic correction of radiation loss in toroidal magnetic configuration

In this paper, the ignition boundary and height of the saddle point as the lowest heating power on the way to ignition for D-3He toroidal magnetic configuration are derived. Fusion fuel cycle involving deuterium and helium-3, along with side reactions is considered. The effect of fuel dilution, incorporating synchrotron radiation and bremsstrahlung power loss with relativistic correction on ignition criteria, is investigated. The results were compared by considering the classical state of bremsstrahlung power. It is found that the height of the saddle point is increased with increasing the ratio of the proton particle density to the fuel deuteron density. The ignition regime shrinks and the minimum value of the Lawson parameter for the breakeven condition and ignition boundaries is reduced due to fuel dilution.

Optimalisasi Penentuan Posisi Access Point Untuk Meminimalisir Area Blankspot Pada Pantai Panrangluhu

This research aims to determine the optimal position of Access Point to reduce blankspot area in Panrangluhu Beach. The research methodology involves several main steps: (1) Research planning is done by collecting important data such as beach plan, Access Point height, location coordinates, distance between points, and RSSI (Received Signal Strength Indicator) value; (2) Access Point and receiver position coordinates are determined in an outdoor environment; (3) RSSI value data received by the receiver is collected using WiFi Signal Meter software. To ensure even network coverage, network quality testing was conducted in the eight cardinal directions at each hotspot point. The results showed that four hotspot points were needed to achieve optimal network coverage throughout the beach area. With this strategic placement, it is expected that there are no areas that are not covered by the network, so that visitors to Panrangluhu Beach can enjoy stable and evenly distributed internet access throughout the beach.

A PLL-Based Doppler Method Using an SDR-Receiver for Investigation of Seismogenic and Man-Made Disturbances in the Ionosphere

The article describes in detail the equipment and method for measuring the Doppler frequency shift (DFS) on an inclined radio path, based on the principle of the phase-locked loop using an SDR receiver for the investigation of seismogenic and man-made disturbances in the ionosphere. During the two M7.8 earthquakes in Nepal (25 April 2015) and Turkey (6 February 2023), a Doppler ionosonde detected co-seismic and pre-seismic effects in the ionosphere, the appearances of which are connected with the various propagation mechanisms of seismogenic disturbance from the lithosphere up to the ionosphere. One day before the earthquake in Nepal and 90 min prior to the main shock, an increase in the intensity of Doppler bursts was detected, which reflected the disturbance of the ionosphere. A channel of geophysical interaction in the system of lithosphere–atmosphere–ionosphere coupling was traced based on the comprehensive monitoring of the DFS of the ionospheric signal, as well as of the flux of gamma rays in subsoil layers of rocks and in the ground-level atmosphere. The concept of lithosphere–atmosphere–ionosphere coupling, where the key role is assigned to ionization of the atmospheric boundary layer, was confirmed by a retrospective analysis of the DFS records of an ionospheric signal made during underground nuclear explosions at the Semipalatinsk test site. A simple formula for reconstructing the velocity profile of the acoustic pulse from a Dopplerogram was obtained, which depends on only two parameters, one of which is the dimension of length and the other the dimension of time. The reconstructed profiles of the acoustic pulses from the two underground nuclear explosions, which reached the height of the reflection point of the sounding radio wave, are presented.

Experimental Study on Proppant Migration in Fractures Following Hydraulic Fracturing

Complex fracture technology is key to the successful development of unconventional oil and gas reservoirs, such as shale. Most current studies focus on how to improve the complexity of the fracture network. It is still unclear whether proppant can enter the branch fractures at all levels after the formation of complex fractures. The effects of construction displacement, proppant particle size, proppant density, fracturing fluid viscosity, sand ratio, and other factors on proppant migration in single fractures and complex fractures were studied using an experimental device independently developed by the laboratory. The results show that the lowest point height of the sandbank and the equilibrium height of the sandbank are directly proportional to the particle concentration and density, respectively, and inversely proportional to the displacement and fracturing fluid viscosity. The equilibrium time of the sandbank is inversely proportional to the displacement, particle concentration, and density, respectively, and proportional to the viscosity of the fracturing fluid. Under the same experimental conditions, the larger the branch angle, the smaller the height of the main/secondary fracture sandbank. In the design of the fracturing process, fracturing fluid with varying viscosities and proppant with different densities should be selected according to the formation conditions and fracturing targets. In the face of long fracture lengths, the combination of low-viscosity fracturing fluid with an appropriate viscosity and low-density proppant can meet the goal of placing proppant over long distances and effectively supporting fractures over extended lengths. Subsequently, high-density proppant or reduced construction displacement are adopted to usefully support fractures in the near-wellbore area. The results of this paper can provide theoretical support for proppant selection and fracturing program design.

On the Determining Physical Factor of Jet-related Coronal Mass Ejections’ Morphology in the High Corona

A solar jet can often cause coronal mass ejections (CMEs) with different morphologies in the high corona, for example, jet-like CMEs, bubble-like CMEs, and so-called twin CMEs that include a pair of simultaneous jet-like and bubble-like CMEs. However, what determines the morphology of a jet-related CME is still an open question. Using high spatiotemporal resolution stereoscopic observations taken by the Solar Dynamics Observatory and the Solar Terrestrial Relations Observatory from 2010 October to 2012 December, we performed a statistical study of jet-related CMEs to study the potential physical factors that determine the morphology of CMEs in the outer corona. Our statistical sample includes 16 jet-related CME events of which seven are twin CME events and nine are jet-like narrow CMEs. We find that all CMEs in our sample were accompanied by filament-driven blowout jets and Type III radio bursts during their initial formation and involved magnetic reconnection between filament channels and the surrounding magnetic fields. Most of our cases occurred in a fan-spine magnetic configuration. Our study suggests that the bubble-like components of twin CMEs lacking an obvious core are related to the expansion of the closed-loop systems next to the fan-spine topology, while the jet-like component is from the coronal extension of the jet plasma along open fields. Based on the statistical results, we conclude that the morphology of jet-related CMEs in the high corona may be related to the filament length and the initial magnetic null point height of the fan-spine structures.

Travelling Ionospheric Disturbances detection: a statistical study of detrending techniques, induced period error and near real-time observables

Due to advances in remote sensing of the Earth's Ionosphere through Total Electron Content (TEC) estimates by Global Navigation Satellite System (GNSS) receivers, it is possible to detect and characterize Travelling Ionospheric Disturbances (TIDs) in both post-processing and, to some extent, in near real-time (NRT). A reliable and precise TEC filtering technique must be adopted to characterize waves accurately. Specifically, TEC detrending is widely adopted to extract the amplitude and period of the detected ionospheric waves from the background ionospheric conditions. Therefore, this study aims to understand and compare how different TEC detrending techniques and their settings impact the ability to extract such parameters. We highlight that the novel Fast Iterative Filtering (FIF) and the Savitzky-Golay filter (SGOLAY) techniques are the most reliable overall compared with moving average (MA), multi-order numerical difference (DD), polynomial detrending (POLY) and Finite Impulse response (FIR) band-pass filter (BUTF). Moreover, the impact of general algorithm settings on the extracted TID period is investigated, such as the Ionospheric Piercing Point (IPP) height and elevation cut-off angle, showing that such parameters drastically impact the retrieved period, especially for slower TIDs. Finally, due to the growing interest in real-time (RT) detection and classification of TIDs, the study proposes techniques for accurately estimating the TID amplitude in an NRT scenario. Such NRT techniques are then compared with the widely used post-processing products, such as the calibrated vertical TEC (vTEC), showing a difference that is mostly lower than the typical noise level of GNSS receivers (0.05 TECu).

Destabilization Mechanism and Stability Study of Collapsible Loess Canal Slopes in Cold and Arid Regions

The combination of seasonal shutdowns, water conveyance, cold, and drought can easily lead to the deterioration of the anti-seepage system and loess foundation of the canal, which contributes to the destruction of the slope. To reveal the failure mechanism of the collapsible loess canal slope, this paper is based on the results of laboratory tests and adopts numerical simulations to analyze the stability of the canal slope under different conditions. The results show that the shear strength indexes and elastic modulus E of loess decrease following an exponential pattern with the increase in wetting-drying and freezing-thawing (WD-FT) cycles. The height of the seepage overflow point yields little effect on the water level behind the impermeable membrane, whereas the height of the water level has a significant effect. In the operation period, the slope under any working conditions is in a relatively stable state. However, the slope with a water level of 4.5 m behind the impermeable membrane tends to be unstable after three WD-FT cycles during the shutdown period. By replacing the surface-degraded loess with sand gravel and picking a depth of 0.9–1.2 m, the slope will maintain a long-term stable state.

Numerical analysis on seismic behavior of a novel steel-timber composite frame column

Steel-timber composite structures are a novel hybrid structural system that combines the advantages of both steel and wood structures, holding great promise for various applications. In this paper, the seismic behaviors of steel- timber composite columns are investigated based on finite element analysis. The reliability of the finite element model is validated by quasi-static test results. Numerical analysis results indicate that the proposed steel- timber composite systems is with high ultimate bearing capacity, full hysteresis loops, and strong displacement ductility, demonstrating excellent seismic performance. The axial compression ratio, steel tube thickness, and flexural point height significantly influence the seismic resistance of the structure.

Numerical simulation of the water landing process of a light civil helicopter in level 5 sea conditions

A helicopter emergency flotation system can provide flotation capability after the helicopter accidentally falls into the water. To solve the problem of attitude change of a helicopter after landing in water, a numerical simulation was carried out on a light civil helicopter with a weight of 3.5 t. It was simulated in level 5 sea conditions, the traveling speed was 15.4 m/s, and the height of the lowest point of the hydrostatic helicopter from the water surface was 250-260 mm, with or without lift, with or without floats. Landing on the water can be done with either basic or elliptical floats and in three different postures. The simulation results show that equipping a helicopter with pontoons can significantly improve its overturning resistance and flotation capabilities, but the impact on a helicopter equipped with pontoons will increase. Landing a helicopter in the water at a certain elevation angle is beneficial to the stability of the helicopter. A helicopter with a basic pontoon is more stable when it lands in the water. The performance is higher than that of the ellipsoidal pontoon, but the pitch stability of the basic pontoon is lower than that of the ellipsoidal pontoon.

Arc erosion behavior and mechanism of Cu/Ti3SiC2 composites in air and c-C4F8/N2 mixture after multiple arc discharges

The arc erosion behavior of Cu/Ti3SiC2 composites in air and c-C4F8/N2 (75/25) mixture was investigated after arc discharges of 1, 100, and 200 cycles. Arc erosion parameters such as breakdown strength, arc duration and breakdown current were recorded. Whether in air or C-N-75-25, the value of the breakdown strength fluctuated with an increase in the number of operations owing to the change in the height of the highest protrusion point, and the breakdown strength remains basically stable after each arc discharge. The arc energy in the C-N-75-25 mixture is lower than that in air. After multiple arc discharges, the erosion pits were scattered over the entire surface within a large area in air. In c-C4F8/N2 (75/25) mixture, although the material surface appeared black owing to carbon deposition, only one crater-like pit was found. In both air and c-C4F8/N2 (75/25) mixture, only a small number of cracks were observed after multiple arc discharges owing to the self-healing effect of the molten Cu liquid flowing into the cracks and condensation. After multiple arc discharges, variations in the ability of the experimental atmosphere to capture electrons resulted in differences in breakdown strength and erosion area. Surface roughness affects breakdown strength but does not play a decisive role. The addition of Ti3SiC2 enhanced the viscosity of the molten pool and increased the work function of the material.

Unidirectional horizontal cyclic behaviors of the monopile-wheel composite foundation in sand

The monopile-wheel composite foundation is an innovative type of offshore wind turbine (OWT) foundation with good bearing capacity. The foundation is subjected to cyclic loads from wind, waves, and tides, so it is necessary to study its horizontal cyclic characteristics. By introducing cyclic degradation constitutive and Rayleigh damping parameters, numerical models are generated and validated by comparing with laboratory experiment results. The laws of horizontal accumulated displacement of the composite foundation are then explored through changes in the cycle amplitude, number, wheel diameter, height of loading point and pre-vertical load. The main findings are that the composite foundation is more likely to reach a stable displacement under constant amplitude cyclic loading compared to that of monopile. Under transient dynamic response (74 % of the horizontal ultimate bearing capacity), accumulated displacement will increase rapidly regardless of the foundation form. The composite foundation has smaller hysteresis loop area and slower accumulation rate of bending moment. The soil pressure weakening of the monopile mainly occurs in front of the pile, while that of the composite foundation mainly occurs under the wheel. After cyclic loading, the V–H envelopes for the composite foundation contract unevenly inwards. Above these, prediction methods for the cumulative displacement, maximum bending moment and V–H envelopes for composite foundation considering cyclic degradation are proposed.

Прогнозування потенційних похибок аномалій висот глобальних моделей геоїда для різних систем припливів

The article presents the method of predicting the errors of height anomalies obtained from high-order global geoid models (EGM_2008, EIGEN_6C4, GECO, XGM2019e2159, SGG_UGM_2) and taking into account different tide systems (free/zero/mean-tide). A correct understanding of how much the choice of the global model height tide system affects the accuracy of calculating the normal heights of the Earth’s physical surface is an important component for obtaining reliable results. The purpose of the work is to predict the potential errors of height anomalies for three main concepts of tidal corrections (tidal systems) used in the creation of global geoid models. Method. The essence of the prediction method is to find a connection between the height anomalies of the global geoid models and the PL-quasi-geoid2021 regional quasi-geoid model. On the basis of the established connection, the prediction of potential errors of height anomalies was made, taking into account the choice of one or another system of tides. The prediction of the errors of height anomalies is implemented on the basis of 200 GNSS stations located on the territory of Ukraine and in the border sector. To find the connection between the heights of the global geoid models and the PL-quasi-geoid2021 regional model, a territory was allocated in the western border sector measuring 48°-52° in latitude and 21°-25° in longitude. For 36 GNSS stations located in the border area, a scale coefficient between global and regional height anomalies was found. Results. In the border sector, the factual errors of height anomalies are estimated at the level of 0.01-0.03 m based on the standard deviation and at the level of the mean square deviation of 0.17–0.18 m, 0.15-0.16 m, and 0.08–0.09 m for the free, zero and mean-tide systems, respectively. The standard deviations of the predicted potential errors for the border sector were 0.02-0.03 m, and the mean square values were 0.17–0.18 m, 0.13 m and 0.06 m for similar tidal systems. The residual errors of height anomalies for the border sector amounted to 0.03 m according to the standard and mean square deviation. Assessment of accuracy prediction of potential errors of height anomalies of models EGM_2008, EIGEN_6C4, GECO, XGM2019e2159, SGG_UGM_2 carried out on the basis of 200 GNSS stations was 0.03 m by standard deviation and 0.15 m (free-tide), 0.13 m (zero-tide) and 0.06 m (mean-tide) by mean square value. Scientific novelty. First implemented was the prediction of potential errors of height anomalies of global geoid models, which was performed by the scale factor for GNSS stations located on the territory of Ukraine and taking into account different tidal systems. Practical significance. The predicted errors of height anomalies make it possible to calculate the normal heights of GNSS stations and points on the Earth’s physical surface with an accuracy of about 3 cm. The obtained results allow the use of height anomalies of global geoid models of high order for more accurate geodetics work.

Multi-objective optimization of assembly free-form cable-stiffened reticulated shell considering the influence of initial states

In this study, we propose a geometric model of free-form grid structures based on the sliding translation method. Furthermore, an end-flattened inserted-plate joint could be applied to a quadrilateral free-form grid structure. The height of the control point was considered as the optimization variable, while the strain energy, geometric integrated index, and ultimate bearing capacity were considered as the optimization objectives. The results demonstrated the influence of the initial prestress and joint stiffness using multi-objective optimization. Based on the effects of the initial prestress, joint stiffness, and initial geometric imperfections, we propose a multi-objective optimization method for the assembly of a free-form cable-stiffened reticulated shell. The feasibility of the optimization method was verified using examples. Compared with the results of the shape optimization, structures having superior mechanical properties and mesh quality were obtained via the combined method for optimizing the shape and initial prestress, which verified the necessity and effectiveness of the combined optimization method. The mechanical properties of the optimized structures were improved by increasing the joint stiffness; in particular, the ultimate bearing capacity was improved. On using the multi-objective optimization method while considering the initial geometric imperfections, the properties of the structure were improved effectively, and the mechanical properties can be guaranteed even after geometric imperfections are applied.

Biomechanical analysis of total arch maxillary distalization using infrazygomatic crest miniscrews: a finite element analysis study

AimTo evaluate the maxillary incisors and canine’s immediate movement tendency using three different power arms (PA) height levels during total arch maxillary distalization supported on infrazygomatic crest (IZC) miniscrews according to finite element analysis (FEA).MethodsThree finite element models of the maxilla were developed based on CBCT imaging of a teenage male patient presenting a Class II Division 1 malocclusion in the early permanent dentition. Maxillary complex, periodontium, orthodontic accessories, IZC miniscrews and an orthodontic wire were digitally created. The PAs were placed between canines and lateral incisors and projected at 4, 7, and 10 mm height distances. After that, distalization forces were simulated between PA and IZC miniscrews.ResultsThe anterior teeth deformation produced in the FEA models was assessed according to a Von Mises equivalent. The stress was measured, revealing tendencies of initial maxillary teeth movement. No differences were found between the right and left sides. However, there was a significant difference among models in the under-stress areas, especially the apical and cervical root areas of the maxillary anterior teeth. More significant extrusion and lingual tipping of incisors were observed with the 4 mm power arm compared to the 7 mm and 10 mm ones. The 10 mm power arm did not show any tendency for extrusion of maxillary central incisors but a tendency for buccal tipping and intrusion of lateral incisors.ConclusionThe maxillary incisors and canines have different immediate movement tendencies according to the height of the anterior point of the en-masse distalization force application. Based on the PA height increase, a change from lingual to buccal tipping and less extrusion tendency was observed for the incisors, while the lingual tipping and extrusion trend for canines increased.

Research on Coaxiality Measurement Method for Automobile Brake Piston Components Based on Machine Vision

Aiming at addressing the problem of the online detection of automobile brake piston components, a non-contact measurement method based on the combination of machine vision and image processing technology is proposed. Firstly, an industrial camera is used to capture an image, and a series of image preprocessing algorithms is used to extract a clear contour of a test piece with a unit pixel width. Secondly, based on the structural characteristics of automobile brake piston components, the region of interest is extracted, and the test piece is segmented into spring region and cylinder region. Then, based on mathematical morphology techniques, the edges of the image are optimized. We extract geometric feature points by comparing the heights of adjacent pixel points on both sides of the pixel points, so as to calculate the variation of the spring axis relative to the reference axis (centerline of the cylinder). Then, we extract the maximum variation from all images, and calculate the coaxiality error value using this maximum variation. Finally, we validate the feasibility of the proposed method and the stability of extracting geometric feature points through experiments. The experiments demonstrate the feasibility of the method in engineering practice, with the stability in extracting geometric feature points reaching 99.25%. Additionally, this method offers a new approach and perspective for coaxiality measurement of stepped shaft parts.