Surface Tilt Research Articles

Acceptance characterization of electron detector in SEM using stainless steel sphere.

Although modern scanning electron microscope (SEM) possess several electron detectors, it is not clear what kind of information is contained in a SEM image taken by a certain detector. Especially the detectors installed in the objective lens are difficult to know their characters. Thus, we propose a simple method to assess the acceptance of electron detector using a stainless-steel sphere. After taking images under certain conditions, say electron beam energy, working distance etc., the image intensity of each pixel point, which is characterized by coordinate (θ, φ), is evaluated. The advantage of this method is the ease of implementation and the whole information of electron emission from the tilted surfaces is contained in the image. Using this information, the acceptance of the detector can be analyzed systematically. In this paper, the traditional Everhart-Thornley detector is analyzed with this method. It is demonstrated how the sphere image changes according to the measurement condition. The ET image quality is strongly governed by working distance but not so much by the electron beam energy. We propose an alternative method to avoid the ambiguity of working distance. Using a needle type specimen stage, the ET image does not vary so much with WD and the reliability of ET image significantly improves.

Assessment of solar energy potential for Bahir Dar city, Ethiopia.

The world's energy consumption is being replaced by renewable energies in large part because of the depletion of fossil fuels and the acceleration of environmental change. This study reports the amount of inward solar radiation in the date range from January 2018 to December 2022 in the Gregorian Calendar for certain areas in Bahir Dar, Ethiopia: 37°E and 11.6°N. On the horizontal surface of the case area, the month with the highest global radiation (monthly average daily) is March, at approximately 42.56 MJ/m2. day; June has the lowest diffuse radiation, at 16.2 MJ/m2.day. Furthermore, April had the most global radiation (monthly average hourly) on the horizontal surface, measuring 9.09MJ/m2.hour, while June had the lowest diffuse radiation, measuring 2.3MJ/m2.hour. In addition, this study predicts the beam, diffuse, and total radiation on the tilted collector using the total available horizontal radiation on a monthly and hourly basis. According to the research, the output of the radiation on the tilted surface towards the equator in the northern hemisphere, azimuth angle, γ = 0°, shows that the highest possible total radiation (monthly average daily) is 48.3 MJ/m2. day (January) and the highest possible total radiation (monthly average hourly) in February, 9.14 MJ/m2.hour at 1:00 p.m.

Subsidence Prediction Method Based on Elastic Foundation Beam and Equivalent Mining Height Theory and Its Application

Grouting technology in overburden separation is recognized as an effective method to prevent surface subsidence and reuse solid waste. This study used mechanical analysis to explore deflection characteristics of key strata and accurately predict and control surface subsidence. Conceptualizing the coal–rock mass beneath the key strata as an elastic foundation, we developed a method to calculate the elastic foundation coefficients for various regions and established an equation for key strata deflection, validated through discrete element numerical simulations. This simulation also examined subsidence behavior under different grout injection–extraction ratios. Additionally, combining the equivalent mining height theory with the probability integral method, we formulated a predictive model for surface subsidence during grouting. Applied to the 8006 working face of the Wuyang Coal Mine, this model was supported by numerical simulations and field data, which showed a maximum surface subsidence of 546 mm at a 33% injection–extraction ratio, closely matching the theoretical value of 557 mm and demonstrating a nominal error of 2%. Post-grouting, the surface tilt was reduced to below 3 mm/m, meeting regulatory standards and eliminating the need for ongoing surface structure maintenance. These results confirm the model’s effectiveness in forecasting and controlling surface subsidence with grouting. The study can provide a basis for determining the grouting injection–extraction ratios and evaluating the effectiveness of surface subsidence control in grouting into overburden separation projects.

Thin Liquid Film View and Shear Stress During the Sliding of Air Bubbles on Tilted Plates.

The challenge when studying the impact and sliding of free-rising air bubbles on tilted surfaces is an experimental limitation in obtaining the film thickness of thin liquid film (TLF) during the bubbles' sliding on tilted surfaces. In this work, spatiotemporal evolution in the film thickness of the moving TLF between a sliding air bubble and a tilted plate was monitored by using a two-wavelength synchronized reflection interferometry microscopy (SRIM) technique. The evolution of the film thickness was directly determined from a timed series of monochromatic interference fringes recorded simultaneously at two different wavelengths. From the film thickness profile, a shear stress map at a given time was determined at different bubble sizes and inclination angles. Results showed that the film thickness of TLFs during the bubbles' sliding on tilted surfaces was in the range of 300-1200 nm, depending on bubble size and tilting angles. Sliding of air bubbles on tilted plates over a thin gap with a few hundred nanometers thickness yielded shear stress in the order of 10-50 Pa. Both the larger bubble size and higher tilting angles yielded a higher shear stress. Experimental results were quantitatively compared to numerical results obtained using the Reynolds lubrication theory. A good match between the two results was achieved. Numerical results suggested that a maximum shear stress exerted on a tilted plate occurred at a 25° tilting angle. This is the first time that the spatiotemporal evolution of TLF during bubbles' sliding on tilted surfaces has been achieved, and the shear stress exerted on the tilted surface has been directly determined.

Numerical simulation of He atmospheric pressure plasma jet impinging on the tilted dielectric surface

The target surface to be treated in reality is often not smooth and horizontal and may also be in different tilting angles. The treatment of the tilted dielectric surface by the atmospheric pressure plasma jet (APPJ) undoubtedly increases the complexity of surface modification. Therefore, a two-dimensional fluid model is established to reveal the internal mechanism of the interaction between the He APPJ and the tilted dielectric surface by means of numerical simulation. The distribution of the gas flow in a small angular range (0°, 3°, 5°, 8°, 10°, and 15°) is studied. In addition, the effects of the tilt angle on the jet morphology, discharge dynamic properties, and species distribution of the He APPJ are emphatically discussed. It is found that the jet morphology and parameters are no longer symmetrical under the tilted surface. With the increase in the tilt angle, the enhanced electric field in the upper surface region leads to the increase in the ionization rate and electron density here, and also accelerates the propagation speed of the jet to the dielectric surface in the atmospheric environment. Driven by the electric field force, the jet is closer to the dielectric surface, resulting in a decrease in the thickness of the cathode sheath and an increase in the surface charge density in the area to the right of the central axis. The influence of the gas flow structure leads to the shortening of the jet development distance and a decrease in the jet velocity on the upper surface. N and O also form higher fluxes on the upper surface due to the increase in the electron density.

Late Palaeozoic structural evolution of the Patch Bank Ridge and Utsira High, northern North Sea

AbstractThis study focuses on the Late Palaeozoic development of the area east of Utsira High in the North Sea, where the stratigraphic section below the late Permian Rotliegend Group is undrilled. We use regional 3D seismic data to study structuring, sediment distribution and geomorphology across the Patch Bank Ridge and Utsira High in the North Sea. The results show that the Stord Basin and the bounding Utsira East fault initially developed during the Late Palaeozoic extension, probably during the Devonian, and that the Utsira Shear Zone controlled the location of Late Palaeozoic depocentres. The Patch Bank Ridge is an uplifted part of the Stord Basin where we identify Late Palaeozoic growth strata along the southern and northern flanks, indicating a similar timing of the structural evolution in this area. Two key wells, in the Sele High and Ling Depression, are used to relate a Late Palaeozoic isopach map with regional structuring, surface tilt and basement morphology to the enigmatic parts of the Late Palaeozoic basin system. Our results supplement regional models for the Late Palaeozoic basin development, we suggest that the deeply eroded Devonian half‐grabens preserved on the Utsira High formed parts of an extensive basin system that show stratigraphic expansion towards their bounding faults. The Top Basement surface at these highs offers several distinct geomorphologies that evolved during three periods of exposure, expressed as (i) a tilted and rugose landscape, (ii) distinct drainage networks and (iii) peneplain surfaces. Cover sediments place these landscapes to the (i) Devonian, (ii) Carboniferous/Permian/Triassic and (iii) Late Triassic periods.

The Impact of Climate Change on Solar Radiation and Photovoltaic Energy Yields in China

Solar photovoltaics is a direct use of solar resources to generate electricity, which is one of the most important renewable energy application approaches. Regional PV output could be affected by the regional patterns of temperature and irradiance, which are impacted by climate change. This study examines the impact of climate change on the energy yields from solar PV across China in the future under the medium-emission scenario (SSP245) and high-emission scenario (SSP585) by calculating PV potential using the data of solar radiation on a tilted surface and temperature. Generally, under the SSP245 scenario, solar radiation increased by 0.8% and 2.15%, and PV energy yields increased by 0.28% and 1.21% in 2020–2060 and 2061–2099, respectively; under the SSP585 scenario, solar radiation increased by 0.73% and 1.35%, and PV energy yields increased by 0.04% and −1.21% in 2020–2060 and 2061–2099, respectively. Under both scenarios, PV energy potential showed an obvious increase in southeast and central China and a significant decrease in northwest China, Tibet, and Inner Mongolia. Therefore, it is suggested that under the medium-emission scenario, climate change could increase the PV energy potential, while under the high-emission scenario, it could inhibit the PV energy potential in China.

Flow field design and experiment of high-efficiency electrochemical milling with large machining area

Materials that are difficult to cut, such as titanium alloys, are widely used in large load-bearing integral components of aircraft, leading to great challenges for manufacturing. Electrochemical milling is a way for machining difficult-to-cut materials through Computer Numerical Control (CNC) trajectory motion. Using a tilted large cathode machining surface and the cut-in feed mode, an efficient and low-cost method is obtained for machining the large integral components. A novel crossed and inclined structure of the flow mode is designed to realize electrochemical milling with a large tilted cathode surface. Compared to the vertical flow mode with one inlet, the proposed flow mode has two inlets that independently supply electrolytes, and the inclined channels make the flow field more stable. Flow field simulations are performed for both the vertical and proposed flow modes. The results show that the proposed flow mode avoids the random diversion of electrolytes and the ultralow flow velocity at both ends of the nozzle area, improving the velocity, uniformity, and stability of the electrolytes. The inclination angle of the crossed and inclined flow field is optimized. Finally, limit feed rate experiments are conducted in two modes, and the limit feed rate is 70 mm/min in the proposed mode. A sector workpiece of a large circular surface with approximately 8.77 mm thickness is machined 9 times by the cut-in electrochemical milling, the material removal rate is 4872 mm3/min, and the surface roughness is superior to 1.15 μm.

Velocity dependence of sensory reweighting in human balance control.

The relative contributions of proprioceptive, vestibular, and visual sensory cues to balance control change depending on their availability and reliability. This sensory reweighting is classically supported by nonlinear sway responses to increasing visual surround and/or surface tilt amplitudes. However, recent evidence indicates that visual cues are reweighted based on visual tilt velocity rather than tilt amplitude. Therefore, we designed a study to specifically test the hypothesized velocity dependence of reweighting while expanding on earlier findings for visual reweighting by testing proprioceptive reweighting for standing balance on a tilting surface. Twenty healthy young adults stood with their eyes closed on a toes-up/-down tilting platform. We designed four pseudorandom tilt sequences with either a slow (S) or a fast (F) tilt velocity and different peak-to-peak amplitudes. We used model-based interpretations of measured sway characteristics to estimate the proprioceptive sensory weight (Wprop) within each trial. In addition, root-mean-square values of measured body center of mass sway amplitude (RMS) and velocity (RMSv) were calculated for each tilt sequence. Wprop, RMS, and RMSv values varied depending on the stimulus velocity, exhibiting large effects (all Cohen's d >1.10). In contrast, we observed no significant differences across stimulus amplitudes for Wprop (Cohen's d: 0.02-0.16) and, compared with the differences in velocity, there were much smaller changes in RMS and RMSv values (Cohen's d: 0.05-0.91). These results confirmed the hypothesized velocity, rather than amplitude, dependence of sensory reweighting.NEW & NOTEWORTHY This novel study examined the velocity dependence of sensory reweighting for human balance control using support surface tilt stimuli with independently varied amplitude and velocity. Estimates of the proprioceptive contribution to standing balance, derived from model-based interpretations of sway characteristics, showed greater sensitivity to changes in surface tilt velocity than surface tilt amplitude. These results support a velocity-based mechanism underlying sensory reweighting for human balance control.

Influence of 3D surface irregularities on the performance of hydrostatic rectangular tilted thrust pad bearing configurations

Tribological behavior of tribo-pairs is strongly dependent on the surface topography. Further, the structural deformation, manufacturing, and assembly errors cause the hydrostatic thrust pad bearings to tilt slightly. The work in this article is aimed to study the effect of tilt and three-dimensional (3D) surface irregularities on the performance of hydrostatic rectangular thrust pad bearings (HRTPB) compensated with capillary restrictors. The 3D surface irregularities are assumed to follow cosine curve. To perform the analysis, a source code has been developed in MATLAB and the Finite Element Method has been used to solve the governing Reynold's equation. The numerical simulation results indicate that the effect of tilt reduces the value of fluid film reaction, fluid film stiffness, and fluid film damping coefficients. The study reveals that 3D surface irregularities results in a higher value of fluid film stiffness and damping coefficient as compared to that of smooth-bearing surfaces.

Bayesian inversion of tilt data using a machine-learned surrogate model for pressurised fractures

We introduce an innovative inversion approach for deducing subsurface fractures through observations of ground surface tilt. We have constructed, evaluated, and applied a surrogate forward model, crafted using conditional Generative Adversarial Networks (cGAN), to forecast the tilts (displacement gradients) at the ground surface caused by subsurface fractures under pressure. Our findings indicate that this surrogate forward model accurately estimates the tilt vector at the surface resulting from the specified pressurised fracture. Even in complex scenarios involving multiple fractures at various depths, the model, which was initially trained on scenarios with single fractures at a fixed depth, performed well. Subsequently, we employed a Bayesian inversion algorithm to derive the optimised solution (the pressurised fracture) for a given set of surface tilt data, leveraging the surrogate forward model. The outcomes demonstrate that the inversion process with the surrogate model is both effective and significantly faster compared to the traditional finite element model that generated the training data.

Performance evaluation and economic analysis of inclined solar dryer for Capsicum annuum L. (Red chilli) drying

This study presents an assessment of the performance and economic viability of solar dryers for drying perishable agricultural products. The dryer was constructed using locally sourced materials such as galvanized iron sheet, M.S. angle, glass, and S.S. wire mesh. The ability to tilt the dryer allows for optimal solar radiation absorption throughout the year in Jodhpur, India. It is well-established that a tilted surface captures more solar radiation compared to a horizontal plane, hence the utilization of a solar dryer in this research. A drying experiment was carried out in January 2023 using the dryer to dehydrate red chilli (Capsicum annuum L.). The maximum stagnation temperature inside the drying chamber was recorded at 65°C, which decreased to 55°C when loaded with 10 kg of chilli, while the outside ambient temperature was 26°C on a clear sky day (from 08:00 h to 18:00 h) in January 2023. Over the course of seven days, the moisture content of the chilli decreased from 80% (wet basis) to approximately 9%. The open sun drying method took 14 days for reducing the moisture content of red chillies to the same level. The dryer's thermal efficiency was calculated to be 16.25%. The economic analysis of the solar dryer indicated a high internal rate of return (IRR) of 82.5% and a short payback period of 1.50 years, highlighting its cost-effectiveness. The cost-benefit ratio was found to be 1.98, demonstrating the potential of solar dryers as a substitute for traditional drying methods. Economic parameters such as net present value (₹40220) and system annuity (₹5430) confirmed the economic feasibility of the system. Inclined solar dryers in remote or rural areas have the potential to significantly reduce postharvest losses and carbon emissions. The adoption of solar dryers would greatly benefit farmers in the arid region of Rajasthan.

A CERES-based dataset of hourly DNI, DHI and global tilted irradiance (GTI) on equatorward tilted surfaces: Derivation and comparison with the ground-based BSRN data

The NASA CERES SYN1deg(Ed4.1) satellite-based products include hourly global horizontal irradiance (GHI), diffuse horizontal irradiance (DHI) and direct horizontal irradiance (DirHI) as well as hourly solar zenith angle (SZA), and the direct normal irradiance (DNI) can thus be calculated by dividing the DirHI by cos(SZA). The spatial resolution of the dataset is 1° latitude by 1° longitude, and the time span is from March 2000 to near present (October 2023 as of this writing). While the GHI of the dataset agrees well with the ground-based Baseline Surface Radiation Network (BSRN) data, the DHI and DirHI, and thus DNI, show appreciable biases against the BSRN data. Nevertheless, the uncertainty of the DHI and DNI, as exhibited in the standard deviations of their differences from the BSRN data, are smaller than results from the DirIndex model, a global-to-beam model, applied to the CERES data, albeit the model is one of the two best out of 140 models according to a study. This means that the original CERES hourly DNI, though biased, renders the spatiotemporal variability better than does the DirIndex model. For this reason, we decided to perform a bias correction on the hourly DHI and DNI. With the corrected hourly DHI and DNI, we are able to use the isotropic model to calculate the global tilted irradiance (GTI) and the global tracker irradiance (GTrI) on an hourly basis. The BSRN DHI and DNI, on the other hand, are available on near-instantaneous time scales (1-, 2-, 3, or 5-minute intervals) and thus are more conducive to the isotropic model, and for the first time, we use the BSRN data to validate the GTI and GTrI, as opposed to GHI and DHI that have previously been used for validation purpose. For comparison and validation, we also use the monthly-mean-based LJCR method, an independent method as used by RETScreen®, which requires monthly mean GHI and DHI, to directly calculate the monthly mean DNI, GTI and, to extend the model, GTrI, and the results agree well with the BSRN data, which proves the LJCR method itself and corroborates the corrected DHI and DNI as well as the derived GTI and GTrI. The monthly mean DHI and DNI from the Whitlock Method, also monthly-mean-based, are evaluated as well, and we find that minor modification can dramatically improve the method.

Spectral speckle displacement in defocused and tilted imaging systems

Speckle patterns offer valuable insights into the surface characteristics or the characteristics of the light generating the speckle. One possible way to extract this information is via spectral speckle correlation (SSC). The cross-correlation between two speckle fields, generated at different wavelengths, can be used for example to determine the roughness of the illuminated surface. Taking defocused measurements of the surface or measuring on a tilted surface leads to a displacement between the speckle, which in turn affects the cross-correlation and leads to errors in the calculated roughness. In this work we present a model to determine the lateral speckle displacement for a change in wavelength in the case of subjective speckle and defocused, tilted objects. This model is therefore applicable to a wide range of applications and allows to estimate and correct for this speckle displacement. Experimental results show sub-pixel accuracy for object tilts up to ±7° and defocus distances up to ±25 mm.

Novel 3D reciprocal space visualization of strain relaxation in InSb on GaAs substrates

This study introduces the reciprocal space polar visualization (RSPV) method, a novel approach for visualizing x-ray diffraction-based reciprocal space data. RSPV allows for the precise separation of tilt and strain, facilitating their individual analysis. InSb was grown by molecular beam epitaxy on two (001) GaAs substrates—one with no misorientation (sample A) and one with 2° surface misorientation from the (001) planes (sample B). There is a substantial lattice mismatch with the substrate, and this results in the generation of defects within the InSb layer during growth. To demonstrate RSPV’s effectiveness, a comprehensive comparison of surface morphology, dislocation density, strain, and tilt was conducted. RSPV revealed previously unobserved features of the 004 InSb Bragg peak, partially explained by the presence of threading dislocations and oriented abrupt steps. Surface morphologies examined by an atomic force microscope revealed that sample B had significantly lower root mean square roughness. Independent estimates of threading dislocation density (TDD) using x-ray diffraction (XRD) and electron channelling contrast imaging confirmed that sample B exhibited a significantly lower TDD than sample A. XRD methods further revealed unequal amounts of α- and β-type threading dislocations in both samples, contributing to an anisotropic Bragg peak. RSPV is shown to be a robust method for exploring 3D reciprocal space in any crystal, demonstrating that growing InSb on misoriented GaAs produced a higher-quality crystal compared to an on-orientation substrate.

Postural impairments in unilateral and bilateral vestibulopathy.

Chronic imbalance is a major complaint of patients suffering from bilateral vestibulopathy (BV) and is often reported by patients with chronic unilateral vestibulopathy (UV), leading to increased risk of falling. We used the Central SensoriMotor Integration (CSMI) test, which evaluates sensory integration, time delay, and motor activation contributions to standing balance control, to determine whether CSMI measures could distinguish between healthy control (HC), UV, and BV subjects and to characterize vestibular, proprioceptive, and visual contributions expressed as sensory weights. We also hypothesized that sensory weight values would be associated with the results of vestibular assessments (vestibulo ocular reflex tests and Dizziness Handicap Inventory scores). Twenty HCs, 15 UVs and 17 BVs performed three CSMI conditions evoking sway in response to pseudorandom (1) surface tilts with eyes open or, (2) surface tilts with eyes closed, and (3) visual surround tilts. Proprioceptive weights were identified in surface tilt conditions and visual weights were identified in the visual tilt condition. BVs relied significantly more on proprioception. There was no overlap in proprioceptive weights between BV and HC subjects and minimal overlap between UV and BV subjects in the eyes-closed surface-tilt condition. Additionally, visual sensory weights were greater in BVs and were similarly able to distinguish BV from HC and UV subjects. We found no significant correlations between sensory weights and the results of vestibular assessments. Sensory weights from CSMI testing could provide a useful measure for diagnosing and for objectively evaluating the effectiveness of rehabilitation efforts and future treatments designed to restore vestibular function such as hair cell regeneration and vestibular implants.

Statistical inter-comparison study of empirical models to estimate the monthly-average daily global irradiation on tilted south oriented surfaces

Accurate determinations of the global solar irradiation received by a tilted surface during the average day of each month (HG (s, 0)) are a prerequisite in different solar energy applications, particularly in design methods. Validation of empirical models to estimate such values is of paramount importance, given the limited number of solar radiation observation sites and meteorological stations capable of providing the real information. Using the information of global irradiation on horizontal surface (HG) recommended in the Schedule of Conditions System Technologies of Low Temperature (SCT) for 52 Spanish provinces, four solar irradiation models of estimation were investigated: Liu and Jordan [1], Aláiz [2], Klein [3] and the one proposed by Censolar. A comparative study based on the statisticians of the distribution of the calculated information indicates that the values of HG (s, 0) estimated with the model of Aláiz agreed well with the reference dates. On the contrary, the Censolar model has got the maximum diversion.

Chemical process effects on sloped surface with changing mass and consistent temperature

The research extensively investigated the turbulent flow patterns surrounding an unbounded inclined plate under the conditions of uniform temperature and variable mass dispersion. Throughout this analysis, the study thoroughly considered the impact of chemical reactions within the system. Focusing on the harmonic inclination of the plate within its plane, the study employed the LT approach to accurately solve the non-dimensional governing equations. In scrutinizing various profiles, the investigation examined the impact of several crucial physical factors: chemical response variable, Schmidt number, thermal Grashof number, mass Grashof number, and duration. This study delves into the intricate influence of various factors on the complex flow dynamics surrounding inclined plates, specifically focusing on heat and mass transfer phenomena. By examining these relationships, the research provides crucial insights into improving the efficiency of thermal and mass transmission processes within systems that incorporate tilted surfaces. Moreover, this knowledge can potentially contribute to advancements in various fields, from renewable energy systems to manufacturing processes, where heat and mass transfer play pivotal roles.

Analysis of the Effect of Tilt Position and Surface Temperature Levels of Solar Panels in Optimizing Solar Panel Performance

The impact of increasing energy needs requires the search for alternative energy, one of which is the use of abundant solar energy. This solar energy is processed through solar panels to convert it into electrical energy. Solar panels can function optimally if they are exposed to maximum sunlight and are at the right working temperature. The challenge faced is, to get maximum sunlight, solar panels must be directed towards sunlight. However, continuous exposure to sunlight causes an increase in the surface temperature of the panel, which ultimately reduces the output power of the solar panel. Therefore, a special design is needed to overcome this problem. The solution implemented is a solar panel optimization system by adjusting the tilt of the panels and using a cooling system connected to the Internet of Things (IoT). The goal of this system is to maximize solar panel performance by maintaining maximum sunlight exposure and panel operating temperature within the appropriate range. The method used is to adjust the tilt of the panel so that it is always at the maximum angle of sunlight, and to use the Peltier effect on water as a surface cooling system for the solar panels. The parameters monitored in this research include voltage from the LDR light sensor, solar panel tilt angle, solar panel temperature, and cooling water temperature from the Peltier effect, as well as voltage, current, and power in comparison between standard solar panels (without a design system) and panels. solar using system design. Monitoring is carried out in real time using Internet of Things-based technology. The test results show that the system can function well as a solar panel optimization system integrated with the Internet of Things. A power increase of 36.91% was achieved by comparing the system without design with the design system (angle adjustment and cooling). In addition, the real-time remote monitoring concept has proven effective in observing the value of electrical energy produced by solar panels in an integrated Internet of Things application. Keywords: solar panels, position, surface temperature, analysis.

Microgravity Decoupling in Torsion Pendulum for Enhanced Micro-Newton Thrust Measurement

To enhance the accuracy of micro-Newton thrust measurements via a torsion pendulum, addressing microgravity coupling effects caused by platform tilt and pendulum mass eccentricity is crucial. This study focuses on analyzing and minimizing these effects by alleviating reference surface tilt and calibrating the center of mass during thrust measurements. The study introduced analysis techniques and compensation measures. It first examined the impact of reference tilt and center of mass eccentricity on the stiffness and compliance of the torsion pendulum by reconstructing its dynamic model. Simscape Multibody was initially employed for numerical analysis to assess the dynamic coupling effects of the tilted pendulum. The results showed the influence of reference tilt on the stiffness and compliance of the torsion pendulum through simulation. An inverted pendulum was developed to amplify the platform’s tilt angle for microgravity drag-free control. Center of mass calibration can identify the gravity coupling caused by the center of mass position. Based on the displacement signal from the capacitive sensor located at the end of the inverted pendulum, which represents the platform’s tilt angle, the pendulum’s vibration at 0.1 mHz was reduced from 5.7 μm/Hz1/2 to 0.28 μm/Hz1/2 by adjusting the voltage of piezoelectric actuator. Finally, a new two-stage torsion pendulum structure was proposed to decouple the tilt coupling buried in both pitch and roll angle. The study utilized theoretical models, numerical analysis, and experimental testing to validate the analysis methods and compensation measures for microgravity coupling effects in torsion pendulums. This led to a reduction in low-frequency noise caused by ground vibrations and thermal strains, ultimately improving the micro-Newton thrust measurement accuracy of the torsion pendulum through the platform’s drag-free control.