The prospect of using Shewhart control charts in assessing the quality of ionometric measurements by the method of adding a sample to a standard

Modern methods of quantitative physical and chemical measurements should necessarily include procedures for quality control of research results. Recently, the procedure for quality control of measurements using control charts is gaining particular popularity in the practice of analytical measurements. To date, the methods of potentiometric studies operating in the territory of the Russian Federation, in most cases, do not include quality control using this control procedure. However, despite the complexity of the implementation and interpretation of its results, it is the use of control charts that allows you to control the quality of ionometric measurements. This is especially important for potentiometric determinations based on the addition method, since the instability of the slope of the electrode function and its deviation significantly contribute to the uncertainty of the measurement results. This article presents the main results of evaluating the use of the Shewhart control chart method for monitoring the repeatability and accuracy of measurement results. The measurement results have been obtained using an improved method of quantitative potentiometric determination of high concentrations (more than 1 gm/cdm) of ammonium ions by the method of adding a sample to the standard. In addition, an experimental substantiation of the fact that the value of the slope of the electrode function significantly affects the accuracy of measurements by the addition method has been presented. It has been revealed that when the angular coefficient of the electrode function is more than 62 mV/pNH4+ at (25±5)°C, deviations of the measurement results from the control standard by more than 50% are observed. It has been found that at (25±5)°С the most accurate results of quantitative determination are achieved when the angular coefficient of the electrode function is from 54 mV/pNH4+ to 62 mV/pNH4+ inclusive.

Revisiting dynamic range and image enhancement ability of contemporary digital radiographic systems

Objectives: To assess the dynamic range and enhancement ability of radiographs acquired with contemporary digital systems. Methods: Five repeated periapical radiographs of human mandibles with an aluminium step-wedge were acquired using two sensor-based and three phosphor plate-based (PSP plate-based) systems and an X-ray unit at ten exposure times 0.020, 0.032, 0.063, 0.080, 0.100, 0.200, 0.320, 0.400, 0.500, and 0.630 s. All images had their brightness and contrast enhanced by two experienced oral and maxillofacial radiologists in consensus and were exported as both the original and enhanced file formats. Mean grey values were obtained from the aluminium steps and tabulated with their corresponding thicknesses for each exposure time, digital radiographic system, and file format. Images with saturated steps were excluded and the mean grey values from the remaining images were averaged to assess image brightness and the angular coefficient of the linear trendlines was generated from the relationship between mean grey values and their corresponding aluminium thicknesses to assess image contrast. Brightness and contrast values were compared using two-way ANOVA with post-hoc Tukey (α = 0.05). Results: PSP plate-based digital radiographic systems had a broader dynamic range. Longer exposure times produced original images with lower brightness and variable contrast (p < 0.05). Subjective enhancement significantly increased or reduced brightness and/or contrast in some systems (p < 0.05). Conclusions: Contemporary digital radiographic systems present different dynamic ranges and exposure-related brightness and contrast. Image enhancement may be a valuable tool at slightly suboptimal exposure times.

Studying the Effect of Light Incidence Angle on Photoelectric Parameters of Solar Cells by Simulation

It is crucial to examine the dependence of photoelectric parameters of solar cells on the light incidence angle. In the present study, two solar cell models have been developed using the Sentaurus Technology Computer-Aided Design software package. The light spectrum AM1.5 has been directed on the frontal surface of solar cells at different angles. It has been found that the angular coefficient of the photoelectric parameters of a solar cell with nanoparticles included, is two times more than that of a simple solar cell. Besides, it has been found that the efficiency of platinum nanoparticles induced solar cells is 2.15 times greater than simple solar cell efficiency. When the light incidence angle has been varied from 0 to 60 degrees, the short-circuit current has changed by 11% for simple solar cells and by 10% for solar cells with nanoparticles. Further, it has been observed that the variation of power for simple solar cells is 12.5%, while it is 10.5% for solar cells with nanoparticles. In addition, the short-circuit current of solar cells with nanoparticles has been found to be linear within a light incidence angle ranging from 0 to 60 degrees.

Fe and As geochemical self-removal dynamics in mineral waters: evidence from the Ferrarelle groundwater system (Riardo Plain, Southern Italy)

A theoretical pattern for Fe and As co-precipitation was tested directly in a groundwater natural system. Several monitoring wells were sampled to identify the different endmembers that govern the hydrodynamics of the Ferrarelle Groundwater System in the Riardo Plain (Southern Italy). In agreement with recent investigations, we found a mix of a deep and a shallow component in different proportions, resulting in a specific chemical composition of groundwater in each well depending on the percentages of each component. The shallow component was characterized by EC ~ 430 µS/cm, Eh ~ 300 mV, Fe ~ 0.06 µmol/L and As ~ 0.01–0.12 µmol/L, while the deep component was characterized by EC ~ 3400 µS/cm, Eh ~ 170 mV, Fe ~ 140 µmol/L and As ~ 0.59 µmol/L. A general attenuation of As and Fe concentration that was not due to a simple dilution effect was observed in the mixing process. The oxidation of Fe(II) to Fe(III) produces solid precipitates which adsorb As from solution and then co-precipitate. The reactions pattern of Fe(II) oxidation and As adsorption gave a linear function between [As] and [Fe], where the angular coefficient depends on the [O2]/[H+] ratio. Chemical data obtained from our samples showed a very good agreement with this theoretical relationship. The investigated geochemical dynamics represented a natural process of attenuation of Fe and As, two undesirable elements that usually affect groundwater quality in volcanic aquifers in central-southern Italy, which are exploited to supply drinking water. Graphic abstract

Performance of models to determine flow rate using orifice plates

ABSTRACT This study aimed to evaluate three methodologies for orifice-plate water-flow estimation by quantifying errors in the flow determinations to propose an appropriate measurement range for each evaluated condition. Two orifice-plate models (nominal diameters of 100 and 150 mm) with 50% restriction in the flow section were evaluated. In the theoretical equations, the discharge coefficient was obtained using the Reader-Harris/Gallagher equation (Method 1) and approximated from experimental data using the angular coefficient of a zero-intercept straight line (Method 2). The recommended measurement ranges for errors that were lower than 5% for the 100 and 150 mm plates were 30 to 65 m3 h-1 and 70 to 130 m3 h-1 using the theoretical equation and 20 to 65 m3 h-1 and 40 to 130 m3 h-1 using the empirical equation, respectively. The Reader-Harris/Gallagher equation (Method 1) adequately estimated the discharge coefficient of the orifice plates; however, the use of empirical equations (Method 3) demonstrated smaller measurement errors and greater rangeability of the evaluated flow meters.

Specific Features of Calculating the Radiant Component of the Heat Flow of Horizontal Bunch from Finned Tubes with Exhaust Shaft

The article discusses the heat exchange of radiation of bunches of round finned tubes with the environment and the exhaust shaft. The system of equations describing the entire set of primary processes that make up the radiation heat exchange of finned bundles is very complex mathematically; therefore, the calculations of radiant heat transfer are usually based on a number of simplifying assumptions with a involuntarily distortion of the real physical picture. The main methods for calculating radiation used in engineering practice, viz. calculation by the average angular coefficient and the zonal method are briefly considered. A refined zonal method for calculating the radiant component of the heat flow of a horizontal bunch of finned tubes with an exhaust shaft is proposed. An experimental study of single-row bunches of finned tubes with different annular steps S1 (64 and 70 mm) was carried out for small Reynolds numbers Re = 130–720 in a wide range of the determining temperature at the beam inlet (16–83 °C). The aluminum finning of the bunch tube had the following parameters: screw finning diameter d = 0.0568 m; diameter of the tube at the base d0 = 0.0264 m; height, step and average fin thickness, respectively, h = 0.0152 m, s = 0.00243 m and Δ = 0.00055 m. Air movement in the bunch was carried out by gravitational traction created by a rectangular exhaust shaft. The experimental bunch was installed above the shaft, and the air was preheated before entering the shaft, which allowed expanding the temperature range of the air at the entrance to the bunch. It was found that incorrect accounting for a bunch reemission with an exhaust shaft when calculating single-row finned bunches causes a decrease in convective heat transfer by 7–25 %.

Mathematical models to predict the energy requirements of Japanese quails from 01-35 days age

The objective of the work was to estimate maintenance and energy gain requirements in the phases: 01 to 15 and 15 to 35 days of age. For maintenance energy, 240 quails (per phase) were used according to a completely randomized design, with four treatments (ad libitum, 75%, 50% and 25%), six replicates, and ten quails per experimental unit (n = 655). Comparative slaughter group (35-initial phase; 25-growth phase). To estimate energy for gain, groups of 15 quails were slaughtered at 3, 6, 9, 12 and 15 days of age, in the initial phase, and groups of 10 quails at 20, 25, 30 and 35 days of age, in the growth phase. All slaughter was performed after a 12-hour fast. The equation of energy retained as a function of consumption made it possible to estimate an endogenous energy loss around 9.30 and 19.59 kcal/kg0.67/day and maintenance requirements at 54.96 and 91.48 kcal/kg0.67/day, respectively for the initial and growth phases. The angular coefficient of the line obtained by the linear relationship between energy retained and carcass weight over time allowed estimating the net weight gain requirements around 1.40 and 1.89 kcal/g, respectively, for the initial and growth. EMA1–15d = (54.96 × P0.67) + (8.30 × WG). EMA15-35d = (92.11 × P0.67) + (8.91 × WG). EMA - apparent metabolizable energy, (Kcal/quail /d); P, live weight (kg); WG, weight gain (g/quail/d).

Mathematical models to predict japanese quail crude protein requirements from 01 to 35 days old

Six hundred and fifty five female Japanese quails were used to estimate the maintenance and protein gain requirements from one to 15 and 15 to 35 days of age. To estimate the protein for maintenance, 240 quails (per phase) were used according to a completely randomized design, with four levels of feed supply (ad libitum, 75%, 50% and 25%) and six replicates of ten birds. Comparative slaughter group (35 and 25 quails, respectively, in the first and in the second phase). To estimate the protein for gain, groups of 15 quails were slaughtered at 3, 6, 9, 12 and 15 days of age, in the initial phase, and groups of 10 quails at 20, 25, 30 and 35 days of age, in the phase growth. All slaughter was performed after a 12-hour fasting. The linear regression equation of the protein retained as a function of crude protein consumption made it possible to estimate an endogenous protein loss around 0.7 and 2.19 g/kg0.67/day and the maintenance requirements at 2.095 and 6.301 g/kg0.67/day, respectively for the initial and growth phases. The angular coefficient of the line obtained by the linear relationship between the retained protein and the carcass weight over time allowed to estimate the net gain efficiencies around 0.284 g/g (initial phase) and 0.310 g/g (growth phase). The equations for predicts daily protein requirements from one to 15 (PB1-15d) and from 15 to 35 days (PB15-35d) were respectively: PB1-15d = (2.095 × P0.67) + (0.851 × WG) and PB15-35d = (6.30 × P0.67) + (0.894 × WG), were P is live weight (kg) and WG is weight gain (g/quail/d).

Influence of the pore space structure and wettability on residual gas saturation

A significant part of hydrocarbon deposits in Russia is in the late stage of development. The distribution of residual oil and gas reserves is determined by the properties of the holding rocks. Estimating of deposits’ residual gas saturation is an important scientific task. The allocation of zones with the maximum undeveloped gas reserves will allow to select areas in long-developed fields for the intensification of production in the most efficient way. To search for such “sweet” zones, it is necessary to determine the factors that provide the value of the residual gas saturation. The reliance of the value of trapped in pores, residual gas saturation on such rock properties as pore space structure and wettability is studied in this article. The influence of formation pressure value and behaviour on making up of residual gas saturation during field development is not accounted in this work. The study of a wide collection of core sampled from productive deposits of the Orenburg oil and gas condensate field, the Vuktylskoe oil and gas condensate field, oil and gas field of Orenburg region, and also three areas in the East Caucasian petroleum province confirmed that the value of structure-trapped oil and gas saturation of carbonate and terrigenous rocks is directly proportional to the ratio of pore diameters and channels connecting them. Herewith the angular coefficient of the regression equation for this relationship for carbonate rocks directly depends on the quantitative characteristics of the predominant (relative) wettability. The obtained relationships make it possible to predict the value of residual gas saturation based on knowledge about the pore space structure and the surface properties of rocks.

A construção de cenários animados no GeoGebra e o ensino e a aprendizagem de funções

RESUMONeste relato, discutiremos especificamente quanto à aprendizagem de funções, salientando nossa experiência com os alunos com altas habilidades/superdotação. abordamos aspectos relacionados ao conceito de funções e a como compreendemos que a tecnologia, mais especificamente o GeoGebra, pode favorecer a aprendizagem destes conceitos. Relatamos alguns aspectos de nossa experiência que evidenciam como a construção de cenários animados no GeoGebra pode implicar na compreensão de conceitos sobre função, por meio das explicações de uma aluna do sexto ano do Ensino Fundamental que revelam que por meio dos cenários animados construídos ela compreendeu conceitos matemáticos de funções importantes, como coeficiente angular, coeficiente linear, funções crescente, decrescente e constante e os relatórios de uma aluna do primeiro ano do Ensino Médio utilizam linguagem matemática e sugerem que o trabalho por um tempo maior com a construção de cenários animados para a aprendizagem de funções, pode favorecer a compreensão e aplicação correta de conceitos matemáticos.Palavras-chave: tecnologia; educação matemática; altas habilidades/superdotação. RESUMENEn este informe, discutiremos específicamente el aprendizaje de roles, destacando nuestra experiencia con estudiantes con altas habilidades / talento. Cubrimos aspectos relacionados con el concepto de funciones y cómo entendemos que la tecnología, más específicamente GeoGebra, puede favorecer el aprendizaje de estos conceptos. Reportamos algunos aspectos de nuestra experiencia que muestran cómo la construcción de escenarios animados en GeoGebra puede implicar la comprensión de conceptos sobre la función a través de las explicaciones de un estudiante de primaria de sexto grado que revela que a través de los escenarios animados construidos ella entendió los conceptos. Las funciones matemáticas, como el coeficiente angular, el coeficiente lineal, el aumento, la disminución y las funciones constantes, y los informes de un estudiante de primer año de secundaria usan lenguaje matemático y sugieren trabajar más tiempo con la construcción de escenarios animados para Las funciones de aprendizaje pueden favorecer la comprensión y la correcta aplicación de los conceptos matemático.Palabras claves: tecnología; educación matemática; altas habilidades / superdotación. ABSTRACTIn this report, we will specifically discuss role learning, highlighting our experience with students with high skills/giftedness. We cover aspects related to the concept of functions and how we understand that technology, more specifically GeoGebra, can favor the learning of these concepts. We report some aspects of our experience that show how the construction of animated scenarios in GeoGebra can imply the understanding of concepts about function through the explanations of a sixth grade elementary student who reveal that through the constructed animated scenarios she understood concepts. Mathematical functions such as angular coefficient, linear coefficient, increasing, decreasing, and constant functions, and the reports of a first-year student in high school use mathematical language and suggest working longer with the construction of animated scenarios for Learning functions can favor the understanding and correct application of mathematical concepts. The abstract can be done in English, with a maximum of 10 lines, single spaced, Times 12, in italics, followed by three keywords. The abstract should contain the purpose of the discussion, the methodology and highlight some of the results observed in the research, but without providing reference authors: they shall come only through the text.Keywords: technology; mathematical education; high skill /giftedness.