Papers by Keyword: Calibration

Abstract: This paper presents an initial investigation into the numerical modeling of additive manufacturing processes for AlNiCo magnets. The research concentrated on calibrating the heat source parameters by utilizing previously published experimental results. The influence of laser power and scanning speed on the laser fusion of AlNiCo5 on SS 304 substrates was investigated through single track experiments. The geometries of the melt pools were measured and utilized as the foundation for model calibration. A two-step calibration methodology was adopted: (1) a simplified 2D model implemented in Octave was used for sensitivity analysis and parameter fitting; and (2) validation was performed using a 3D model within the commercial software Simufact Welding software. Parameters calibrated through 2D simulations could be directly transferred to the 3D context. However, while the calibration procedure enabled accurate fitting for individual tracks, it resulted in globally non-optimal parameters, suggesting that process parameters influence laser penetration depth.

Abstract: Designing a low-cost weather station requires careful consideration of the selection of sensors used. The use of inappropriate or poorly calibrated sensors can result in inaccurate data acquisition, which ultimately affects the quality of weather observations. This paper conducts a literature study related to sensors that are often used in low-cost weather stations. Based on the study results, the most frequently monitored quantities are temperature, humidity, and atmospheric pressure. To demonstrate the calibration analysis of weather sensors, tests were conducted on the BME280 sensor, which is widely used to measure these three parameters. This test was conducted at a meteorological calibration laboratory that has been certified by the National Accreditation Committee (KAN). The test was carried out by building a sensor node equipped with a reference sensor, so that the test could be carried out simultaneously and at the same time. This aims to ensure that the BME280 sensor readings can be compared directly with the calibrated reference sensor, so that the accuracy and precision of the sensor can be evaluated more comprehensively. In this test, the BME280 sensor was tested before and after adjustment. The initial calibration results showed a deviation in pressure and temperature readings that exceeded the specified tolerance limits. After the adjustment process, the BME280 sensor showed a significant improvement in accuracy, with readings that were more consistent and closer to recognized measurement standards.

Abstract: We present an accurate calibration strategy for TCAD model parameters of a 1200V vertical Silicon-Carbide (SiC) MOSFET, considering key physical characteristics of SiC such as trap distribution along the SiC/SiO₂ interface, mobility degradation, and Schottky contact for the p-type region. Initially, static characteristics are used to calibrate the SiC/SiO₂ interface traps and mobility model parameters in the low electric field region after matching the simulated doping profile with SIMS. Subsequently, capacitance-voltage (C-V) characteristics are calibrated by considering both the capacitance in periphery and the Schottky effect for the p-type well (PWell) region. Finally, the calibrated model was used to evaluate SC withstand time using mixed-mode TCAD simulation. The simulated static and dynamic performance, including short-circuit (SC) withstand time, are in good agreement to the measurements with an error rate of less than 10%. In summary, we propose a TCAD model parameter calibration method for highly accurate simulation of 1200V vertical SiC MOSFETs, which will contribute to finding process and design solutions that consider both static and dynamic characteristics.

Abstract: Computer simulation plays a crucial role in the designing of sheet metal stamping processes for the prediction of process output, before try-out die sets are manufactured. Different commercial software packages are available on the market for sheet forming simulation, but their accuracy can vary, depending on the selection of the pre-processing parameters and on their formulation. Software benchmarking can be used to select the most appropriate package for a given application. Calibration, i.e. the inverse determination of the correct set of pre-processing parameters, can be used for improving the prediction accuracy. The scientific literature on numerical simulations of sheet metal forming processes presents some examples of software calibration and very few examples of benchmarking. The literature generally neglects a critical and important issue: the inherent variability of real forming processes. In this work, the experimental results of two similar multi-stage deep drawing processes are presented and compared to the simulation output of two popular software packages used in the industry. Statistical methods for benchmarking and calibration are proposed. The paper demonstrates how benchmarking can be misleading if process variability is not considered.

Abstract: Fiber-reinforced cementitious matrix (FRCM) composites have been increasingly used to strengthen existing concrete and masonry structures in the last decade. Two guidelines are available for the design and construction of FRCM strengthened members: ACI 549.4R (2013) and CNR-DT 215 (2018). Both these guidelines employ the effective strain, i.e. the strain at which the composite action is lost, as key parameter for the evaluation of the capacity of FRCM strengthened members. The American guideline ACI 549.4R (2013) employs the results of clevis-grip tensile tests on FRCM coupons to determine the composite effective strain. Such strain is determined by the Italian guideline CNR-DT 215 (2018) combining the results of direct shear tests on FRCM-substrate joints and of tensile test of bare fiber textile. The effective strain is strictly related to the matrix-fiber bond behavior, which can be expressed by the interface shear stress-slip relationship, i.e. the cohesive material law (CML). The effective strain is not sufficient for a full understanding of the structural response of strengthened members, since the knowledge of the CML is needed to predict important parameters such as the crack pattern or the location where debonding occurs in beams strengthened in flexure. This paper provides a simple procedure to obtain the CML from the load response obtained by direct shear tests of FRCM-substrate joints. The procedure is discussed and applied to the case of poliparaphenilene benzobisoxazole (PBO) FRCM-concrete joints previously tested by the authors.

Abstract: This paper presents the results of the application of new unique techniques based on plasma nanotechnology in metallurgy and materials science. In recent years, a team of authors have developed the solutions for extraordinary problems arising in the conditions of metallurgical enterprises related to the production of synthetic materials and control of manufactured products, namely, the methods for the production of various structural materials and optimization of methods for their non-destructive testing by atomic emission spectral analysis (AESA). The paper points out some aspects of ongoing research, in particular, an innovative technique that allows obtaining ultrapure samples of white corundum by plasma melting of alumina in a reactor. This method also allows obtaining ultrapure aluminum at the output, which can be used for the purposes of hydrogen energy. In the course of the research, the criteria for thermal protection, temperature conditions and optimal parameters of the plasmatron were determined. In order to carry out the studies of metals and alloys by AESA method, a new global analytical method was developed, which made it possible to take into account the influence of various important parameters, including third elements, background plasma radiation, etc. This method has been preliminary tested on emission spectrometers made in Russia and can significantly reduce the error in the determination of low concentrations of elements. In addition to the consideration of these parameters, the method makes it possible to perform high-precision calibration of atomic emission spectrometers of the same type (produced in series), using not a set of several tens of approved standard samples, but only two standard samples. For each area, patent applications were formed and filed.

Abstract: In this work the calibration of an Alternative Current Potential Drop (ACPD) system was performed to monitore laboratory mechanical tests on marine environment under cathodic protection. The calibration was done on CT type specimens of API 5L X65 steel dimensioned according to ASTM E1820 standard., The crack propagation during a tensile test with displacement control in an ACPD equipment was monitored through the performs points collection by two channels: one that monitors the crack growth and another that monitors a region free of crack. Using a profile projector and graphical data processing and analysis software, the area of ​​the fracture surface of the specimen was meansured, which allowed to correlate a crack size with a corresponding value of potential drop and the calibration curve. In order to verify verify the efficacy and precision of the technique, step loading tests were performed on API 5L X65 steel test specimens, submerged in synthetic sea water under the overprotection potential of-1300mV_Ag/AgCl. The results of the calibration showed few dispersed errors, and the main factors of this dispersion may be related to the geometry of the specimen and with variations in current flow density, which is influenced by corners and edges and by the presence of pick-up inductive. The calibration and its effectiveness can be verified through the results of the tests in marine environment, presenting crack lengths close to the actual values, confirming the effectiveness of the ACPD technique.

Abstract: Tapioca starch adulterated with dolomite is sold in markets, but this adulteration cannot be identified by normal visual inspection. Near infrared (NIR) hyperspectral imaging has been successfully used as a non-destructive method of identifying various characteristics of food, therefore it was tested to identify dolomite adulteration. Adulterated tapioca starch samples were prepared by adding dolomite in the range of 0.5-100% (wt/wt). Samples (N=400) of pure tapioca starch (0) and adulterated tapioca starch (1) were divided into calibration set (N=300) and a prediction set (N=100). All samples were scanned using NIR hyperspectral imaging (935-1720 nm) and spectra were pre-processed using Savitzky-Golay first derivative differentiation pretreatment in order to obtain the optimal conditions for establishing a classification model. Partial least squares-discriminant analysis was carried out to evaluate the accuracy of classification tapioca starch adulterated with dolomite. The results showed the total accuracy of prediction for classification was 100%. Therefore, NIR hyperspectral imaging was demonstrated to have a potential for use in detecting adulteration of tapioca starch with dolomite.

Abstract: Water activity in foods can result in detrimental microbial activity during storage. The usual methods of water activity measurement involve destruction of the sample. Near infrared (NIR) hyperspectral imaging has previously been successfully used as a non-destructive method to determine various physical and chemical characteristics of a variety of foods. Therefore, this method was tested to determine whether it could be used to measure water activity of mamón cakes, a popular sponge cake developed in the Philippines. Individual samples (n = 178) were divided into a calibration set (n=119) and a prediction set (n=59). These samples were tested using NIR hyperspectral imaging (935-1720 nm) with a smoothing spectral pretreatment selected for developing the calibration model. Partial least squares regression was used to establish the model in order to predict the water activity. The results showed the accuracy of the calibration model in prediction that gave a correlation coefficient of 0.767 and the root mean square error of prediction of 0.0130. It was therefore concluded that NIR hyperspectral imaging has a potential for use and application for measuring the water activity of mamón cakes.

Abstract: When the measurable quantities are not given a value for the amount considered or found a standard for the quantity, it requires calibra-tion. Calibration is a preparation process before starting the test. It is a process of finding the relationship between two unknown quanti-ties. If one of the quantities is known because it is made or set with another device, another measurement is made as similar way as possible with the first device using a second device. The measurable quantities may differ in two devices which are equivalent. The de-vice with the known or assigned correctness is called the standard. The second device is the unit under test, test instrument or any of several other names for the device calibrated. [1] The process can reduce the error margin of the tested measurement and that will prevent any unnecessary problems that may harm human in certain application applied.