Flatness Measurement Research Articles

Form Deviation Uncertainty and Conformity Assessment on a Coordinate Measuring Machine

Coordinate measuring machines are widely used in the industrial field due to their ease of automation. However, estimating the measurement uncertainty is a delicate task, especially when controlling for deviation, given the large number of factors that influence the measurement. A precise estimate of the uncertainty is crucial to avoid incorrect conformity assessments. The purpose of this study is to control geometrical-form tolerance specifications, taking into consideration their associated uncertainty. A surface fitting model based on the least squares criterion is proposed, allowing one to obtain the variance–covariance matrix by iterative calculation according to the Levenberg–Marquard optimization method. The form deviation is then evaluated following the Geometrical Product Specifications (GPS) Standard, and its associated uncertainty is estimated using the guide to the expression of uncertainty in measurement (GUM) propagation of the uncertainty law. Finally, the conformity assessment is performed based on the measured deviation and its associated uncertainty. Different results for the measurement of straightness, flatness, circularity, roundness, and cylindricity are presented and detailed. This model is thereafter validated by a Monte Carlo simulation, and interlaboratory comparisons of the obtained results were performed, which showed satisfactory outcome. This contribution is of great use to manufacturing companies and metrology laboratories, allowing them to meet the normative guidelines, which stipulates that each measurement result must be accompanied by its associated uncertainty.

Investigation of error sources in absolute flatness measurement using Fizeau interferometer

Investigation of error sources in absolute flatness measurement using Fizeau interferometer

Use the external radiotherapy StarTrack detector to study the electron beam profile.

To assess the electron beam dose verification, and to investigate the dependability and stability of the Startrack two-dimensional array. The is cross-secional study was conducted from January to April 2021 at the Baghdad Centre for Radiotherapy and Nuclear Medicine, Baghdad Medical City, Baghdad, Iraq. Quality assurance measurements were made using a StarTrack two-dimensional detector on an electron beam with an energy of 12MeV at 1.5cm depth for field sizes 6cm×6cm and 14cm×14cm. The detector was positioned 100cm from the source to the surface of the linear accelerator infinity. Testing was done using the International Electrotechnical Commissioning protocol. There was a significant difference between field sizes 6cmx6cm and 14cmx14cm (-4.97±0.83, -2.01±0.68, respectively) (p<0.05). The beam profile measurements of penumbra, flatness and symmetry were within limits ±2 cm, and ±2 cm, 2%, respectively. The percentage of output dose curve against distance showed instability in crossline for 6cm x 6cm and 14cm x 14cm field size. The output dose was found to be above the tolerance level, and should be corrected before patient treatment for 12MeV energy electron beam therapy.

Mini-ridge filter designs for conformal FLASH proton therapy

The present study designed a mini-ridge filter capable of generating a 30 mm spread-out Bragg peak (SOBP) specific to the proton FLASH beamline for use in proton FLASH mouse studies. Proton FLASH therapy delivers ultra-high dose rates exceeding 40 Gy/s, necessitating instantaneous SOBP generation via static method. The TOol for PArticle Simulation (TOPAS) was used to model the FLASH beamline, which enabled accurate replication of beam characteristics identified from measurements, and ensured accurate dose calculations. Comparisons between simulated and measured peak widths and R80d values, accurate to within 1 mm, verified the accuracy and reliability of Monte Carlo code. Two mini-ridge filters of different materials were designed and optimized using MATLAB, simulated with TOPAS for SOBP verification, and fabricated using 3D-printing or computer numerical control manufacturing. The results indicated strong agreement between the simulated and measured SOBP widths for the polylactic acid mini-ridge filter but with discrepancies observed in the range and flatness measurements, which may be due to the use of 3D printing. By contrast, the aluminium alloy mini-ridge filter achieved excellent results, generating a 31.6 mm SOBP width with 0.89% flatness. Therefore, the present study validated the accuracy of our Monte Carlo code in simulating the FLASH beamline and the feasibility of our mini-ridge filters.

Rail Flatness Measurement Based on Dual Laser Triangulation

Rail Flatness Measurement Based on Dual Laser Triangulation

Nesting BiVO4 nanoislands in ZnO nanodendrites by two-step electrodeposition for efficient solar water splitting

Photoanodes with a large electrochemically active surface area, rapid charge transfer, and broadband light harvesting capacity are required to maximize the photoelectrochemical (PEC) water splitting performance. To address these features, we demonstrate that 3D hierarchal ZnO nanodendrites (NDs) can be sensitized with BiVO4 nanoislands by chemical and thermal treatments of electrodeposited Bi metal films. The flat band measurements and optical characterization suggested that the resulting heterojunction had type-II band alignment with a viable charge transfer from BiVO4 to ZnO NDs. In parallel, PL analysis revealed inhibition of the charge recombination rate by the electron transfer between BiVO4 and ZnO NDs. Upon AM 1.5 G illumination, BiVO4/ZnO NDs heterojunction yielded the highest photocurrent efficiency (0.15 mA·cm−2 at 1.2 V vs. NHE), which was attributed to its enhanced surface area (due to the presence of small dendrite branches), extended broadband light absorption extending from UV to visible light regions, and the most efficient interfacial charge transfer as proven by electrochemical impedance spectroscopy (EIS) studies. Besides, the incident photon-to-current conversion efficiency and applied bias photon-to-current efficiency tests confirmed an improved spectral photoresponse of the heterojunction based photoanode, particularly towards the visible light spectrum. The results outline a promising synthesis route for building heterojunctions between visible light active and wide band gap semiconductors for the use as a highly efficient photoanodes in a PEC cell.

Data preprocessing for flatness measurements of large precision workpieces

Abstract Measuring the flatness error of large precision workpieces quickly and accurately is a difficult problem. A new method for preprocessing flatness measurement data based on MSE (mean squared error) is proposed. A mathematical model of a new data preprocessing method was established, and the mathematical formula for model solving was derived in detail. The data were measured by digital level on the plane of the granite base with dimensions of 2340 m×1540 mm. The new method and SmartLevel (basic measurement system of the level computer) were used to calculate and process the data. The flatness errors after diagonal evaluation were 4.07 μm and 3.90 μm, respectively. The relative error of the two was 4.36%, which confirmed the reliability and accuracy of the new method. The data results show that this method can be effectively used for the engineering measurement of the flatness of large precision workpieces.

Batch Specular Plane Flatness Measurements Based on Phase Measuring Deflectometry.

Flatness is a critical parameter in the manufacturing industry, directly impacting the fit and overall product performance. As the efficiency of manufacturing continues to advance, there is an increasing demand for more accurate and efficient measurement techniques. Existing methods often struggle to strike a balance between precision and efficiency. In response, this article introduces a novel approach that is capable of achieving high-precision and rapid measurements concerning multiple surfaces. By enhancing the traditional phase measuring deflectometry (PMD) method, employing a matching technique based on polar lines and normal vector constraints to address discrete surface measurement challenges, and implementing a plane pre-positioning method to tackle low efficiency in binocular matching and solving, we successfully performed swift and synchronized measurements for a large batch of specular surfaces and obtained the three-dimensional surface profile of each measured surface. Through experimental validation, the method proposed in this paper can perform the batch measurement of specular planes while maintaining high measurement accuracy.

Heat transfer measurements on a flat plate and cylinders at high velocity conditions: Comparison of calculation models with infrared thermography

In this study, various heat transfer measurement models using infrared (IR) thermography were applied to a flat plate and cylinders to examine the accuracy and suitability of the measurements in a transonic blow-down test facility recently developed at Korea Aerospace University. Experiments were performed under three inlet velocity conditions for the flat plate, and for the cylinders, two diameters, two turbulence intensity levels, and five inlet velocity conditions. The surface temperature distribution during the experiment was acquired using an IR camera, and the surface heat transfer coefficient (HTC) was calculated using four HTC calculation models based on the one-dimensional semi-infinite (1D SI) solid assumption: step change (STEP), Duhamel's superposition (DUH), 1D finite volumetric model (1D FVM), and linear regression model (LRM). The LRM showed minimum deviation with reference correlation for the flat plate heat transfer measurements, while STEP, DUH, and 1D FVM showed increased deviations at higher mainstream velocity conditions. The measurements by LRM at the cylinder stagnation location showed the most comparable value with the reference correlation, whereas STEP and FVM showed about 10% deviation from the reference. It is concluded that the LRM is the most suitable heat transfer calculation model for high velocity tests because the model excludes the ramping data during the transient tests, and it can also obtain the local adiabatic wall temperature experimentally.

Development of stable S-scheme 2D–2D g-C3N4/CdS nanoheterojunction arrays for enhanced visible light photomineralisation of nitrophenol priority water pollutants

The investigation focused on creating and studying a new 2D–2D S-scheme CdS/g-C3N4 heterojunction photocatalyst. Various techniques examined its structure, composition, and optical properties. This included XRD, XPS, EDS, SEM, TEM, HRTEM, DRS, and PL. The heterojunction showed a reduced charge recombination rate and more excellent stability, helping to lessen photocorrosion. This was due to photogenerated holes moving more quickly out of the CdS valence band. The interface between g-C3N4 and CdS favored a synergistic charge transfer. A suitable flat band potential measurement supported enhanced reactive oxygen species (ROS) generation in degrading 4-nitrophenol and 2-nitrophenol. This resulted in remarkable degradation efficiency of up to 99% and mineralization of up to 79%. The findings highlighted the practical design of the new 2D–2D S-scheme CdS/g-C3N4 heterojunction photocatalyst and its potential application in various energy and environmental settings, such as pollutant removal, hydrogen production, and CO2 conversion.

A comparative investigation for flatness and parallelism measurement uncertainty evaluation using laser interferometry and image processing

A comparative investigation for flatness and parallelism measurement uncertainty evaluation using laser interferometry and image processing

Surface flatness measurement of medium-thick plate based on Laser point cloud

Surface flatness measurement of medium-thick plate based on Laser point cloud

Analysis of Workbench Flatness Measurement and Product Result of 3 Axis CNC Router Machine

The development of technology in the industrial sector is increasing rapidly, especially the application of computers in the field of machinery. Demands from consumers who want good quality workpieces, precision, completed in a short time and in large quantities, will be easier to work with a CNC Router machine. Surface flatness is an absolute thing that must be considered in the machining process, especially the 3 Axis CNC Router machine. This type of research is an experimental research, using Dutch teak wood as a workpiece with a height of 15 mm, a length of 100 mm and a width of 80 mm, the machining process uses a 3 Axis CNC Router Machine. The flatness of the workbench is first measured, then the product is prepared with a depth of 2 mm in the product area. The research uses a variation of the spindle speed of 600 rpm, 800 rpm and 1000 rpm. After that, measurements are taken to obtain the flatness value. Measuring flatness using a Dial indicator measuring instrument with accuracy (1µm). The best product flatness test or the lowest value is (32.00 µm) obtained from the spindle speed of 1000 rpm and the most uneven product evenness is (56.00 µm) obtained from the spindle speed of 600 rpm, knowing the effect of the flatness value of the workbench on the product flatness value 3 Axis CNC Router Machine, that the flatter the workbench, the flatter the product results. The results of the research can be used to refine machining strategies to achieve optimal machining.

Pengembangan Instrumen Tes Tipe Higher Order Thinking Skills (HOTS) Pokok Bahasan Bangun Ruang Sisi Datar

This study aims to determine the process and analyze the quality of the HOTS-type test instrument development on flat side space and measure students' higher-order thinking skills. This type of research is research and development with the Formative Research (Tessmeer) model. The test subjects in this study were class XI.3 students at SMP Negeri 30 Makassar, totaling 30 students. Based on the research results, it is known that 1) the development process using the Formative Research (Tessmeer) model through 4 stages, namely the preliminary stage, the self-evaluation stage, the prototyping stage, and the field test stage. 2) the quality of test development is declared valid with a CVR (Content Validity Index) value, the average total score is 1 with a very appropriate category or is in the interval 0.68-1.00, practically based on the results of the questionnaire analysis of student responses 89.07% with the response category "Very Positive”, reliable with an average of 0.752 and 0.866 in the high category (reliable), the average difficulty level of the total score is 0.69 and 0.49 in the medium category, and the different power of the average total score is 0.42 and 0.49 in the good category. 3) students' critical thinking ability averaged 67.61, which was in the good category. Thus, this HOTS-type test instrument can be used to measure students' high-order thinking skills.

The alterations in ocular biometric parameters following short-term discontinuation of long-term orthokeratology and prior to subsequent lens fitting: a preliminary study

Purpose To investigate the alterations in biometric parameters among Chinese adolescents over an extended period of wearing orthokeratology lenses, as well as the subsequent changes after a one-month cessation of lens usage prior to the secondary lens fitting. Methods Twenty-four myopic patients aged 7–14 were enrolled in this 37-month prospective observational study. Ocular biometric parameters were measured in the study. Ocular biometric parameters were assessed, and the utilization of Generalized Estimating Equations (GEE) was employed in the analysis to address the correlation between the two eyes of each participant. Results The axial length (AL) increased by 0.55 mm after 36 months of lens wearing and further increased to 0.62 mm at the 37-month follow-up compared to the initial measurement. The differences in AL elongation per month between the 37-month time point and the 12-, 24-, and 36-month marks of lens wearing were found to be statistically significant (p12-month = 0.001; p24-month = 0.003; p36-month = 0.001). Following the cessation of lens wear for 1 month, there was no significant complete recovery observed in the flat and steep keratometry values. However, the intraocular pressure and anterior chamber depth returned to their baseline levels. Conclusions The AL elongation undergoes alterations during temporary discontinuation of lenses, with the flat and steep keratometry measurements remaining significantly flatter compared to the baseline. However, the intraocular pressure and anterior chamber depth return to their initial levels after one month of lens cessation.

Genetic Algorithms and Machine Learning Enhanced Laser Displacement Sensor Point Cloud Augmentation for Low-Cost, Large-Scale Flatness Measurements

Genetic Algorithms and Machine Learning Enhanced Laser Displacement Sensor Point Cloud Augmentation for Low-Cost, Large-Scale Flatness Measurements

Effectiveness of Four Different Obturation Techniques on the Penetration Depth of Bioceramic Sealers into the Dentin Tubules: An In Vitro Study

Introduction: We aimed to assess the penetration depth of bioceramic sealers into the dentin tubules following different root canal obturation techniques included (A) warm vertical compaction, (B) carrier-based technique, (C) cold lateral compaction, and (D) single-cone obturation. Methods: This study utilized 40 extracted lower first premolars with developed apices and circular and straight root canals. The roots were eliminated to achieve an 11-mm length with a coronal flat measurement point. ProTaper Next rotary system was used for instrumentation. For obturation procedures, gutta-percha and Bio-C bioceramic sealer were employed, and the roots were randomly divided into four study groups, including (A) warm vertical compaction, (B) carrier-based technique, (C) cold lateral compaction, and (D) single-cone obturation. Depth of sealer penetration into the tubules was assessed using scanning electron microscopy. Result: We found significant differences in the penetration depth of bioceramic sealers based on obturation techniques (p &lt; 0.001), location of dentin tubules (coronal, middle, or apical third) (p &lt; 0.001), and the interaction between obturation techniques and location (p = 0.042). Conclusion: The warm vertical compaction and carrier-based technique showed superior penetration depth into the dentin tubules.

Dynamic Detection of Vigorous Worm in Infected Host

The Internet has developed to give many benefits to mankind. The access to information being one of the most important. Worms cause major security threats to the Internet. Worms are software components that are capable of infecting a computer and then using that computer to infect another computer. The cycle is repeated, and the population of worm-infected computers grows rapidly. Smart worms cause most important security threats to the Internet. The ability of smart worms spread in an automated fashion and can flood the internet in a very short time. A new class of smart worms, referred to as Camouflaging worm (C-Worm in short). C-worm is different from traditional worm. C-worm intelligently manipulate its scan traffic volume over time. Motivated by observations, we designed a novel Spectrum Based detection Scheme to detect the C-worm. This scheme uses Power Spectral Density (PSD) distribution of the scan traffic volume and its corresponding Spectral Flatness Measure (SFM) to distinguish the C-worm traffic from background traffic. This scheme is effectively detecting not only the C-worm but traditional worms as well. The goal is to prevent, detect and delete the smart worms as well as traditional worms.

A Comparison of CMM and CMA Capabilities in Product Feature Verification Metrology

To control variations and guarantee that a part will function as intended in an assembly, measurement verification must be conducted with specialized metrology equipment. The Coordinate Measuring Machine (CMM) and the Articulated Arm CMM (AA-CMM) are analyzed in this comparative study, to identify their respective advantages and disadvantages when measuring flatness. The goal of this pilot study is to detect the measuring limitations of each machine and propose a methodology to identify appropriate use of each device based on its capabilities. For measuring flatness, contact and contactless measurement experiments were designed. As expected, it is observed that the CMM performs better than the CMA in flatness measurement because it has a higher resolution [1]. By looking at the measured flatness obtained during the experiment, it was determined that the CMM had a smaller minimum measurable tolerance in all permutations of the test when compared to its counterpart. Resulting in the proposal of different functional working envelopes for these machines. Establishing working envelopes permits the use of both machines for overlapping working purposes as the versatility of CMAs in Geometry verification in settings where CMMs cannot be deployed, could have a great impact as long as they operate on the corresponding working envelopes defined in this research, which were defined as follows: CMM has a minimum measurable tolerance of 0.0006in, CMA contact, has a minimum measurable tolerance of 0.0024in and CMA contactless, has a minimum measurable tolerance of 0.0045in.

Strain gauge measurements of an oscillating heat pipe from startup to stable operation

Oscillating heat pipe (OHP) devices offer high heat flow (Q) and low thermal resistance (Rth) capabilities with convenient form factors for applications in spacecraft and terrestrial thermal management. Though prior measurements have used intrusive strain measurements in a single OHP turn to study the complex thermal-fluid mechanisms of OHP operation, minimally-intrusive external strain measurements on the casing of a multi-turn OHP have not been previously reported. Here, we affix strain gauges to the exterior casing of an ammonia filled flat plate OHP and use strain measurements to quantify the frequency response of ammonia vapor pressure fluctuations over a broad Q range. For all Q, the Fourier transformed strain signals referenced to the Q=0 W background are well-described by a low-pass filter fitting function with a low-frequency amplitude a and characteristic “knee” frequency c. In all cases, a increases with increasing Q due to the enhanced vapor pressure fluctuations at larger thermal loads. In the startup regime of Q<10W, we observe large temporal deviations in the strain response, large Rth>0.1K/W, and c values that increase with increasing Q. In the stable operating regime for Q near 100W, we observe a stable frequency response, a minimum value of Rth=0.02K/W, and Q-independent c values that saturate near 10Hz. Our strain gauge findings are consistent with a mechanism of intermittent boiling near startup followed by stable vapor plug/liquid slug motion at higher Q. Thus, our measurements show that externally placed and minimally invasive strain gauges canprovide diagnostic capabilities and additional insight into operation in both the startup and stable regimes for multi-turn, lightweight OHP devices used in aerospace and terrestrial thermal management applications.