Papers by Keyword: Reproducibility

Abstract: Gauge repeatability and reproducibility are becoming a versatile tool for determining the effectiveness or adequacy of manual and automatic measuring systems. The knowledge of variation is essential as variation is inherent in every measurement process and is sometimes unpredictable. Understanding and controlling variation in measurement systems is critical to reducing variability. This paper presents a design of an experiment to analyze gauge capability and uses the same designed experiment to test and compare the variation for two automatic measurement systems. Three factors were determined as a starting point and were compared at two levels. The test results were analyzed using the expanded ANOVA method in Minitab. Significant conclusions were drawn out and a recommendation for further work is suggested.

Abstract: Solvent extraction is commonly used to extract oil from most seeds, including Moringa oleifera (MO). Oil extraction is a critical step in the production of cosmetics, pharmaceuticals, and other products that require the maximum amount of oil from the seed. On the other hand, MO as a coagulant need to be oil-free for coagulation performance. Therefore, optimization of oil yield is kept up to date. The extraction time, seed to solvent ratio, and particle size are the most optimised parameters reported on MO. Most Soxhlet extraction methodologies reported in the past mention a time range for extracting oil from the seed. Following the same extraction time, however, frequently results in variation in the yield of MO obtained. Because of this lack of reproducibility in oil yield, it has been demonstrated that using extraction time as a basis for monitoring the point at which maximum oil yield is achieved is not completely reliable. The range of ratios, solvent type, moisture content of the seed and the heating mantle vary from one to another. This study is focusing on oil extraction based on the number of siphons(8,16,24,32 siphons) using 2 different solvents (ethanol with a boiling point of and n-henaxe with a boiling point of) and shows that the optimum oil yield is at 16 siphons. It is also important to see when the extraction should stop for industrial scale to be cost effective. This method is then validated with two batches of MO seed for reproducibility. In addition, the use of polar solvents such as ethanol may also remove more protein and minerals from the seed, which can affect the quality and performance of the defatted MO seed in coagulation assays. Hence, EDS tests are included for preparing the suitable solvent used based on mineral removal.

Abstract: This paper deals with the comparison of non-destructive methods of measuring modulus of elasticity by ultrasonic pulse velocity method and impact resonance method. Main research is focused on scattering of measured data, where by different volunteers were used the methods mentioned above on same test sample. This paper does not deal with the conversion relationships between individual methods, but it outlines the suitability of the chosen method in participation with the nature of samples, the difficulty of measurement and the expected reproducibility and interpretability of the measured data.

Abstract: While much numerical studies have been done on short channel carbon nanotube field effect transistors (CNT-FETs), there are only a few numerical reports on long channel devices. Long channel CNT-FETs have been widely used in chemical sensors and biosensors as well as light emitters. Therefore, numerical study is helpful for a better understanding of the behavior of such devices. In this paper, we numerically analyze long-channel CNT-FETs by solving the continuity and charge equations self-consistently. To increase the accuracy of simulation, filed-dependent mobility is applied to the equations. Furthermore, a method is proposed to obtain the electrical current of transistors as a function of CNT diameter. Obtained results are in good agreement with the previous experimental data. It is found that compared to a CNT-based resistor, the dependence of current on diameter is much higher in a CNT-FET. Finally, reproducibility of transistors based on the arrays of random CNTs of 1-2 nm diameter in terms of the CNTs number is also investigated.

Abstract: The global transportation of fossil fuels occurs mainly by sea and grows annually, along with the risks to the marine ecosystems, especially in the vicinity of navigation routes. Numerical simulations able to reproduce realistic oil spill scenarios can be utilised for planning risk mitigation actions. This study is based on simulating the behaviour and weathering rates recorded during the first 24 h after an oil spill that occurred in an estuarine region. The numerical system used is the ECOS (Easy Coupling Oil System) oil spill model coupled to the three-dimensional hydrodynamic model Telemac-3D. The hydrodynamic results were analysed considering wind velocity fields and currents, which are the dominant forces in the displacement and behaviour of the oil. The reproducibility of the oil leak was confirmed by comparing the results of the simulations with the official environmental emergency report of the accident. The strong correlation between the simulation and the report showcases the capacity of the simulation methodology to reproduce real case scenarios of oil spills.

Abstract: In recent years, the static modulus of elasticity is one of the most discussed property of hardened concrete. The aim of this article is to show results of 6 performed experiments focused on test results precision. The measurements were made according to the standards ISO 6784 and ISO 1920-10. More than 20 participants (laboratories) from Europe took part in these experiments. Test results were compared using the statistical methods for interlaboratory comparison. Repeatability and reproducibility, which provide more detailed information about range of expected values of elastic modulus, are the most discussed characteristics in the article.

Abstract: The aim of this paper is to summarize the results of 11 experiments which focused on assessing the precision of results of fresh concrete testing. The observed characteristics are slump test, flow table test, density and air content. More than twenty participants (testing laboratories) took part in these experiments. The test results were evaluated with statistical methods used for evaluations of interlaboratory comparisons. The article deals especially with the values of repeatability and reproducibility, which provide further understanding of the interval within which it is possible to expect with the given probability the test results measured in one or more laboratories.

Abstract: Magnetite (Fe₃O₄) nanoparticles were successfully synthesized by ascorbic acid mediated reduction of Fe (acac)₃, without using any intentionally added capping agent. Fine tuning of synthesis parameters such as dropping rate of ascorbic acid solution, addition temperature, reflux temperature and time, and concentration of reactants have yielded nanoparticles of size 15±4 nm. Synthesis is observed to be highly reproducible. Possible mechanism for growth of Fe₃O₄ nanoparticles is suggested. Nanoparticles are characterized for their size, crystallinity and crystal structure, elemental analysis for impurities (if any), and presence of any additional oxide phases – by SEM and TEM, XRD, EDAX and XPS spectroscopy, respectively.

Abstract: Polymerase chain reaction optimization for inter simple sequence repeat primers is a key factor to obtain accurate and reproducible results for gene mapping, studying the genetic structure of populations, plant passporting, phylogenetic analysis. Changing temperature conditions, the amount of amplification cycles and concentration of reaction mixture components is allowed to vary the number of bands obtained by this method. This article is result of preliminary research of method selection for molecular analysis. It is aimed to show how to adjust the profile of inter simple sequence repeat fragments by polymerase chain reaction for four model species Stipa lessingiana, Poa intricata, Equisetum fluviatile and Pteridium aquilinum. The working concentrations of magnesium chloride for primer ((СТС)₃GC) and ((АС)₈YG) were 2.5 mM for 0.63 units of Taq DNA polymerase and for primer ((СА)₆GG) it was 4.5 mM for 1.25 units. Sharply defined banding was observed from the minimal amount of DNA 5 ng per reaction, with primer concentration from 10 to 80 pmol and dNTPs concentration 0.2 mM. Optimal hybridization temperatures were 51.9 °C for primers ((АС)₈YG), ((СА)₆GG) and 50.0 °C for ((СТС)₃GC). The best imaging results were obtained when setting up electrophoresis in 1.9% agarose gel

Abstract: The paper presents new procedure of methodology for statistical assessment of measurement systems variation (methodology known in the literature as Measurement Systems Analysis, MSA). This procedure allows for calculation and monitoring in real time (that is on-line) of measurement system (MS) characteristics which determine its usability for manufacturing process control. The presented solution pointed out the gap in process control, which consists in lack of methods for monitoring measurement processes in the on-line way. Their key point consists of taking samples that are also needed for the process control chart for the needs of the MSA method. This means that the samples are taken directly from the production line and during the production process. The method is combined with the standard procedure of statistical process control (SPC) with the use of process control charts. It is based on two control charts. The first one is called AD-chart (Average Difference chart) and it allows to estimate the variation between the operators and stability of the monitored measurement system. The second control chart illustrates the %R&R index (Repeatability and Reproducibility) and allows to monitor the MS capability.The paper also presents authors’ proposal of guidelines about the reference value for the %R&R index calculation and assessment. Recommendations and guidelines for choosing the reference value are based on two criteria: information about sample and manufacturing process variation and the purpose of using MS (product or process control).