Experimental Plan Research Articles

Multi Response Modelling and Optimisation of Copper Content and Heat Treatment Parameters of ADI Alloys by Combined Regression Grey-Fuzzy Approach

This paper deals with the austempering of ductile iron (ADI) and clarifies the influential austempering parameters during the production of ADI. During the austempering process, the heat treatment parameters can be varied, thus influencing the final microstructure and, of course, the mechanical properties of ADI. To appropriately conduct experiments and obtain good results, an experimental plan was developed using the Design Expert 13 software. Along with the heat treatment parameters, the influence of the copper content on the ADI toughness, tensile strength, and elongation was determined. The obtained results from this experiment were used to develop unique mathematical models which describe the influences of heat treatment and copper content on the observed mechanical properties of ADI samples. These mathematical models can be applied to predict the analysed mechanical properties of ADI in the dependence of heat treatment parameters and copper content in base ductile iron. For the multi response optimisation of toughness, tensile strength, and elongation, a hybrid grey-fuzzy technique was presented as a significant contribution to the enhancement of the analysed mechanical properties. Consequently, the copper content and heat treatment parameter levels that resulted in the maximal mechanical properties’ functions were defined.

Optimization of Spray Characteristics of Full Cone Nozzles Used in Pesticide Application Using the Taguchi Method

The present study aims to reduce the amount of pesticide that can be released into environment, soil, air, and water by minimizing the type of nozzle and the use of excess pesticides by making use of the Taguchi method. For this purpose, studies were carried out to determine the spray characteristics of the pesticide. The sodium fluorescein was used in the experiments. In this study, the effects of the nozzle-to-surface distance (spray height), spray pressure, nozzle orifice diameter, and nozzle position angle on the droplet diameter and flow characteristics were investigated using the Taguchi method. The mean diameter values were determined first. Then, the volumetric median diameter (VMD) was considered as performance parameter and L9(34) orthogonal sequence was chosen as the experimental plan for four parameters that were determined. Calculating the VMD considered as the performance characteristics, optimum results were obtained using 6 bar spray pressure, 100 mm spray height, 30o nozzle position angle, and 1.10 mm nozzle orifice diameter. The VMD values were calculated using the image processing method and the effects of the parameters on the droplet diameter were interpreted using charts.

EXTRACTION OF CHROME FROM FERROCHROME PRODUCTION SLAG USING THE SULFURIC ACID METHOD

Currently, the development of industrial waste recycling processes that reduce the anthropogenic load on the biosphere and ensure the rational use of natural resources is an urgent task. Technogenic waste from ferrochrome production contains chromium, which is one of the most toxic components of industrial waste. To extract chromium from them, the most acceptable method is acid leaching. The purpose of the work is to study the influence of temperature, process duration and H2SO4 concentration on the extraction of chromium from high-carbon ferrochrome slag into a sulfuric acid solution. Using mathematical planning of a 3-factor experiment, experiments were carried out to extract chromium from the slags of high-carbon ferrochrome production. The H2SO4 concentration was varied from 5 to 95% by diluting the concentrated acid. The duration of the process ranged from 10 to 180 minutes at S:L = 1:30, the temperature varied from 22 to 90 °C. Results and discussion. The maximum transition of chromium into acid occurs at a temperature of 76-90 °C and a process duration of 145-180 minutes. The degree of extraction reaches 97.9%. The smallest amount of chromium, about 20 mg/L, passes into the weakly concentrated H2SO4 solution, the degree of leaching is low and equal to 20.6%. When using 50% H2SO4, the highest degree of transition of Cr (94.8%) from ferrochrome slag to sulfuric acid occurs at a high temperature of 90 °C in 150-180 minutes. Deeper extraction of chromium cations into acid occurs at 80-90 °C. The maximum content of Cr3+ in the acid is achieved in 46-107 minutes and amounts to (0.33-0.68)%. Conclusions. It was revealed that with increasing process duration and increasing temperature, the degree of extraction increases. The maximum transition of chromium into acid from high-carbon ferrochrome slag occurs at a temperature of 76-90 °C and a process duration of 145-180 minutes. The degree of extraction reaches 97.9%. An increase in the temperature of the process of leaching chromium from VUVC with concentrated sulfuric acid initiates the extraction of chromium from the raw material.

PRELIMINARY STUDY OF THE AREAL ROUGHNESS PARAMETERS IN 3D PRINTING OF WORKPIECES OF PLA MATERIAL

The field of production engineering is constantly expanding, as novel manufacturing procedures are being introduced and spread in the industrial environment. The creation of complex parts by the application of some kind of printing process is a relatively new method compared to the other traditional chip-removal processes. It can be applied in various fields, where the greatest advantage can be utilized, which is the lower restrictions on the geometry of finished parts. In this paper, the surfaces on 3D printed parts are being studied. The effect of the printing speed, layer height and nozzle temperature are analysed on the surface roughness of the experimental workpieces. The experimental setup plan is designed according to the full factorial design method. The results of this preliminary study are the general determination of the affecting factors on the surface roughness.

Optimisation of some technological factors of pretreatment by pullulanase enzymatic hydrolysis combined with hydrothermal process to produce resistant starch (RS3) from rice flour ingredients

The purpose of the study was to conduct a multi-factor experiment and optimize some technological factors of pretreatment by pullulanase enzymatic hydrolysis combined with hydrothermal process to produce resistant starch (RS3) from rice flour of IR50404 paddy variety. The multi-factor experimental plan used the Box-Behnken planning model with 3 independent variables corresponding to the variation range: Pullulanase enzyme concentration (1.5-2.5%); Hydrolysis temperature (52-58oC); Hydrolysis time (8-12 hours). The objective functions include: RS3 resistant starch content (%), reducing sugar content (%), and solubility (%). The experiments were conducted under the same conditions with the parameters determined from single-factor experiments: Prepare enzymatic hydrolysis solution with rice starch/water concentration of 15% at pH 5.5; Hydrothermal mode includes 3 heat treatment/cooling cycles: Autoclaving (130oC, 60minutes) →Cooling and storage time(4oC, 18 hours). Experimental data processing and optimization used Design -Expert 7.1 software with expected function algorithm with the desire that the RS3 resistant starch content, reducing sugar content and solubility reach their maximum values, corresponding to the important coefficients of 5/5, 4/5, and 4/5. The results were the determination of the optimal enzymatic hydrolysis pretreatment regime with pullulanase enzyme concentration of 2.2%, hydrolysis temperature of 54.4oC for 10.4 hours, corresponding to RS3 resistant starch content reached 47.58±0.22%, reducing sugar content reached 14.12±0.08%, and solubility reached 68.52 ± 0.18% after hydrothermal process.

Toxicity of Essential Oil from Plectranthus amboinicus (Lamiales: Lamiaceae) against Sitophilus zeamais (Coleoptera: Curculionidae)

Abstract Maize weevil, Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), is a major insect pest of stored grain products, causing extensive damage to both grain quantity and quality. The application of synthetic insecticides to control this insect has a negative impact on human health and the environment. Essential oils derived from natural plants are recognized as user- and environmentally friendly alternatives. The use of essential oils from Lamiaceae, which exhibit toxic properties through contact, fumigation, and repellency, provides another option for protecting stored products from various insect pests. The aim of this research was to study the chemical constituents and insecticidal activity of essential oil extracted from the leaves of Indian borage, Plectranthus amboinicus (Lour.) (Lamiales: Lamiaceae), against S. zeamais adults.The chemical composition of the essential oil was analyzed using gas chromatography–mass spectrometry, and the insecticidal activity against adult maize weevils was investigated in the laboratory. The experimental plan followed a completely randomized design with five replications of seven treatments or concentrations of the essential oil: 0, 0.5, 1, 1.5, 2, 2.5, and 3 µl/ml air. The results revealed that the essential oil from the leaves of P. amboinicus contained 23 chemical constituents (97.51%). Thymol (49.96%) was identified as the main compound followed by caryophyllene, trans-α-bergamotene, 3-methyl-4-isopropylphenol, γ-terpinene, p-cymene, caryophyllene oxide, humulene, 4-hydroxy-2-methylacetophenone, 2-hydroxy-2-phenylbutyramide, (2-oxazolidinylidene)malononitrile, hexestrol, terpinen-4-ol, 1-octen-3-ol, (1R,7S,E)-7-isopropyl-4,10-dimethylenecyclodec-5-enol, α-bisabolene, isoaromadendrene epoxide, α-farnesene, 4-carene, α-muurolene, 3-hexen-1-ol, ledene oxide-(II), and α-myrcene, respectively. The fumigation toxicity (median lethal concentration) to maize weevil adults at 48 h was 292.53 µl/ml air. The essential oil from the leaves of P. amboinicus, when applied at a concentration of 2 µl/ml air for 144 and 168 h, resulted in adult maize weevil mortality exceeding 90%. The highest concentration tested (3 µl/ml air) led to exceptionally high mortality rates, with 99–100% of the maize weevils succumbing to the treatment. These findings demonstrate that essential oil from P. amboinicus leaves holds promise as a fumigation insecticide for reducing the population of maize weevils, a significant pest in stored products.

Research and Development of New Polylactic Acid (PLA) Fiber Concrete Materials and Performance Research

Polylactic acid (PLA) fiber concrete has broad application prospects in the field of building materials. This article summarizes the current research status of fiber-reinforced concrete and its importance in improving the mechanical properties of cement-based materials. In view of the modification of the physical properties of PLA fiber, experimental research is conducted to improve its mechanical properties, solve the problem of natural degradation, and explore the application of anti-corrosion materials. In terms of concrete preparation technology, experiments were carried out to study uneven fiber distribution and compatibility with cement slurry to determine the optimal proportion and processing technology. Mechanical property tests and theoretical studies have shown that fiber type and length have a significant impact on the performance of concrete, and it is necessary to further explore the mechanical properties of the transition zone between the fiber and the concrete matrix. Aiming at the durability, fire resistance and other issues of PLA fiber concrete, relevant experimental research plans were proposed. Finally, the mechanical properties of ultra-high toughness PLA fiber concrete were optimized by improving the mix design, optimizing fiber type and dosage, and surface treatment technology. These research results provide an important reference for the wide application of ultra-high toughness PLA fiber concrete in building structures.

Applied Mathematics: Building Theory and Practice

The explanation, assessment, and resolution of real-world problems in a variety of fields, including the social sciences, engineering, biology, physics, and economics, depend heavily on applied mathematics. By applying mathematical models, algorithms, and computational techniques, experts may interpret complex events, improve workflows, and offer creative solutions. Moreover, by aiding in the formulation of hypotheses, the planning of experiments, and the interpretation of results, applied mathematics fosters a greater understanding of both natural and artificial systems.Applied mathematics is based on strong theoretical frameworks that facilitate modeling, analysis, and prediction. These foundations span several areas of mathematics, such as calculus, linear algebra, differential equations, probability theory, and optimization. With the use of these tools, scientists may develop mathematical representations of real-world events that accurately reflect their essential features and dynamics. Theoretical insights also enable practitioners to investigate complex systems and derive actionable knowledge through the development of analytical methodologies, numerical algorithms, and simulation tools.

The Influence of the Geometry of Grooves on the Operating Parameters of the Impeller in a Centrifugal Pump with Microgrooves

Centrifugal pumps are one of the most widely used machines in all branches of industry. For this reason, their efficiency has a significant impact on energy consumption in global industry (about 20%). It is extremely difficult to design low-specific-speed centrifugal pumps at acceptable efficiency levels due to increasing losses in the impeller (hydraulic, volumetric, and mechanical). This article presents the influence of the geometric features of grooves (width, depth), and the number of them, on the operating parameters of the impeller in a centrifugal pump with microgrooves. The principle of operation of this solution involves the passive control of the flow in the boundary layer using rectangular grooves. The grooves are made inside the flow channels of the impeller and are intended to reduce hydraulic losses occurring during flow. This is mainly due to a reduction in losses in the boundary layer. In order to determine the influence of the grooves’ parameters on the energy characteristics of the impeller, numerical calculations and experimental measurements were performed on 15 sets of impellers, which were obtained using experimental planning methods. The CFD calculations were conducted in order to understand the flow phenomena that occur in the impeller with the microgeometry and their effect on a reduction in internal flow losses. Based on the research results, useful guidelines for designing impellers with low-speed characteristics were formulated.

Fabrication of a Low-Cost Fused Filament Fabrication-based 3D Printer and Investigation of the Effect of Process Parameters on Mechanical Properties of 3D-Printed Samples

Additive Manufacturing (AM) techniques add material layer-by-layer to fabricate parts or products, compared to subtractive manufacturing processes, where the material is removed to obtain the final product. The most common method among AM techniques is fused filament fabrication (FFF), which uses filament material to print objects into end products. The present study's aims include designing and fabricating a custom FFF-based 3D printer and investigating the effects of three process parameters on the tensile properties of the 3D-printed samples. Initially, the 3D printer was successfully fabricated. The locally fabricated 3D printer uses Marlin Firmware 2.0 as programming code to control different functionalities of the printing processes. After fabrication and calibration, the printer 3D-printed a few samples successfully. Moreover, a design of experiments plan was formulated to print tensile specimens based on the levels of the process parameters. Tensile testing was performed, and the analysis of variance (ANOVA) confirmed that the process parameters significantly affected the tensile strength. The effects of the process parameters were then analyzed, along with the defect formation and microstructure analysis. Finally, optimum parameters for printing PLA parts with better tensile properties were figured out for the designed 3D printer.

An Experimental Study on Hard Turning Performance of DIN 17350 Tool Steel

The main objective is to investigate the effects of cutting speed, feed rate and depth of cut on surface roughness Rz in hard turning process of DIN 17350-tool steel (60÷62HRC) under dry condition. The full factorial experimental planning design with the help of Minitab 19 software was applied to evaluate the main effects and interaction effects of input machining parameters. The experimental results indicate that feed rate and depth of cut cause the stronger impact on the objective function Rz than cutting speed. In addition, the interaction effects of cutting speed and feed rate as well as the cutting speed and depth of cut have significant influences on the output, but the interaction effect between the feed rate and depth of cut has little impact. Furthermore, cutting speed of 1400 rpm, feed rate of 0.05 mm/rev, and cutting depth of 0.1 mm should be recommended for the smaller surface roughness Rz values.

Requirements of the experiment

The purpose of the experiment is to derive inferences about the causal effects of a subset of the characteristics of the units of a target population (explanatory characteristics - treatment factors) on characteristics that express the performance of these units (response characteristics). To achieve this objective, the effects of the treatment factors in the sample must manifest themselves as in the target population. This attempt requires the construction of a valid and representative sample of the target population. It is achieved if the experiment plan and its execution satisfy the experiment requirements. These requirements are considered in this article.

Частная полумарковская модель как инструмент снижения сложности задачи оценивания устойчивости функционирования элементов информационной инфраструктуры, подверженной воздействию угроз

Decision-making on information infrastructure (II) security for its sustainable functioning in the face of threats requires a tool to assess the sustainability of its individual elements. The application of the semi-Markov model to assess the stability of the functioning of elements of II exposed to threats in a direct setting is associated with the increasing complexity of the description of the object of delineation (parametric space) in step progression from the number of the considered impacts, which reduces its practical significance. However, no studies have been found in the scientific literature to reduce the complexity of the semi-Markov model. The article presents an approach to reducing the complexity of modeling by adopting correct assumptions when forming the initial data. Given the conditions under which it is possible to take a series. It was a cost to limit the applicability of the model by significantly reducing the complexity of the modelling. The problem statement and the modified transition graph are given. The novelty of the problem statement is to take into account the limitations on the available resources for the restoration of functionality of the element. To explain the physical essence of the modeling process, a thought experiment with a model is introduced. To solve the problem, the following methods were used: a) expert methods for extraction of initial data; b) mathematical models of private semi-Markov processes; c) methods of transformation of Laplace; r) methods of planning of experiment. Illustrative examples and graphs accompany the task sequence demonstration. As a result of the experiment, the regularities of the studied process, the existence of which was proved formally. As a result of the experiment, the regularities of the studied process were revealed, the existence of which was officially proved. The results of the study broaden knowledge about the application of methods of Markov processes to assess the stability of the functioning of AI elements in relation to the conditions of the impact of threats.

Use of hydroxyapatite as a support in the immobilization of Thermomyces lanuginosus lipase for application in the production of biodiesel using a by-product as lipid raw material.

The use of new materials in the field of biofuel production has been represented as a step in the development of remarkable catalysts. The use of lipases in the production of biodiesel is often seen as a cost-limiting step, as the operating expenses in recovering such catalysts can lead to unfeasible market expectations. In this study, hydroxyapatite (HAp) particles were evaluated as a support to immobilize commercial lipase, following application in ethyl ester synthesis. First, hydroxyapatite was synthesized through the co-precipitation method at constant pH and selected as a support to be used in enzyme immobilization. The characterization of the biocatalyst support materials produced was carried out using DRX, BET, FTIR, TGA, and SEM analysis. The lipase from Thermomyces lanuginosus was then immobilized in the matrices, and, subsequently, there was transesterification of the vegetable oil deodorization distillate (VODD). The biodiesel samples generated showed that they were within commercial standards, achieving ester conversion greater than 96.5%. Other properties such as density (0.87 g.cm-3) and viscosity (4.36 mm2.s-1) meet the specifications required by ASTM to be used as a biofuel. In the experiment planning technique, the results revealed an experimental trend and a defined behavior: a higher lipase loading in the immobilization and the use of temperatures in the range of 40-50 °C favor high conversions of ethyl esters. Thus, this confirms that the enzymatic chemical catalyst was able to form the main fatty acid esters even using a residual lipid raw material.

Optimization of the Parameters Influencing the Antioxidant Activity and Concentration of Carotenoids Extracted from Pumpkin Peel Using a Central Composite Design.

It has been discovered that the peel of a pumpkin (Cucurbita maxima), regarded as a waste product of pumpkin processing, has significant amounts of carotenoids and other antioxidants. This study aims to identify the most effective extraction parameters for an ultrasonic-assisted extraction method to extract the total carotenoids (TCs) and assess the antioxidant activity (AA) of pumpkin peel. To determine the effects of the extraction time, temperature, and material-to-solvent ratio on the recovery of TCs and AA, a response surface methodology utilizing the central composite design (CCD) was used. The extraction temperature (6.25-98.75 °C), extraction duration (13.98-128.98 min), and solvent ratio (0.23-50.23 mL) were the variables studied in the coded form of the experimental plan. The carotenoid concentration varied from 0.53 to 1.06 mg/g DW, while the AA varied from 0.34 to 7.28 µM TE/g DW. The findings indicated that the optimal extraction parameters were an 80 °C temperature, a 10 mL solvent ratio, and a 100 min extraction time. The study confirmed that the optimum extraction conditions resulted in an experimental TC yield of 0.97 mg/g DW and an AA of 7.25 µM TE/g DW. Overall, it should be emphasized that the extraction process can be enhanced by setting the operating factors to maximize the model responses.

IN SILICO PREDICTION OF POTENTIAL DERMATOLOGICAL EFFECTS OF A SYNTHETIC ANTIOXIDANT

Nowadays, in silico prediction has become standard in the development of new drugs. Computer screening of known drugs provides an efficient approach to repurposing these agents for new indications. This sparked our interest in conducting an in silico analysis of ethylmethylhydroxypyridine succinate (EMHPS) for pharmacological effects potentially useful in dermatology. The aim of this study is to perform an in silico search for the effects of the synthetic antioxidant EMHPS that are potentially useful for the treatment of skin diseases. Retrospective computer prediction of the EMGPS structure was performed using the Drug2ways methodical approach and the PASS (Prediction of Activity Spectra for Substances) program online. The EMHPS molecule consists of two active fragments, which were analyzed separately. In the structure of 2-ethyl-6-methyl-3-hydroxypyridine, 125 types of activity were predicted, while in succinate - 734 types of activity. From the array of prognostic data, effects that may be relevant for the treatment of skin diseases were extracted. These include anti-seborrheic, anti-alopecia, anti-eczema, anti-pruritic, and anti-infectious effects, as well as photosensitizing action and lack of skin irritation. According to the forecast, these effects may be due to the influence of the components of the EMHPS molecule on membranes, antioxidant protection, the state of connective tissue, enzymes, and signaling pathways involved in the development of inflammation, as well as on the pathogenicity factors of microorganisms. Therefore, in silico screening of new types of activity in EMHPS allowed us to predict some effects useful in the treatment of dermatological pathology. Undoubtedly, the results of the forecast must be verified by practice, but they allow us to create a working hypothesis and approach the planning of experiments more rationally, which corresponds to modern trends in pharmacology.

A Review on the Use of Large Language Models as Virtual Tutors

AbstractTransformer architectures contribute to managing long-term dependencies for natural language processing, representing one of the most recent changes in the field. These architectures are the basis of the innovative, cutting-edge large language models (LLMs) that have produced a huge buzz in several fields and industrial sectors, among the ones education stands out. Accordingly, these generative artificial intelligence-based solutions have directed the change in techniques and the evolution in educational methods and contents, along with network infrastructure, towards high-quality learning. Given the popularity of LLMs, this review seeks to provide a comprehensive overview of those solutions designed specifically to generate and evaluate educational materials and which involve students and teachers in their design or experimental plan. To the best of our knowledge, this is the first review of educational applications (e.g., student assessment) of LLMs. As expected, the most common role of these systems is as virtual tutors for automatic question generation. Moreover, the most popular models are GPT-3 and BERT. However, due to the continuous launch of new generative models, new works are expected to be published shortly.

Numerical Study of Drilling Parameters with Al 356 Alloy Using Bacterial Foraging Optimization

Numerical Study of Drilling Parameters with Al 356 Alloy Using Bacterial Foraging Optimization

Ecotoxicological studies of direct and indirect genotoxicity with Artemia: a integrative review

Artemia is a brine shrimp genus adapted to extreme habitats like ranges salinity from 5–25 g/L and in temperatures from 9 to 35 °C. It is widely distributed and used as an environmental quality biomarker. Artemia franciscana and Artemia salina species are commonly used in ecotoxicological studies and genotoxicity assays due to their short life cycle, high fecundity rate, easy culture, and availability. Thus, considering the importance of these tests in ecotoxicological studies, the present study aimed to present Artemia genus as a biological model in genotoxicity research. To this end, we reviewed the literature, analyzing data published until July 2023 in the Web of Science, SCOPUS, Embase, and PubMed databases. After screening, we selected 34 studies in which the genotoxicity of Artemia for various substances. This review presents the variability of the experimental planning of assays and biomarkers in genotoxicity using Artemia genus as a biological model for ecotoxicological studies and show the possibility of monitoring biochemical alterations and genetic damage effects. Also highlight innovative technologies such as transcriptomic and metabolomic analysis, as well as studies over successive generations to identify changes in DNA and consequently in gene expression.

A comprehensive review of parametric optimization of electrical discharge machining processes using multi-criteria decision-making techniques

Optimization of electrical discharge machining (EDM) processes is a critical issue due to complex material removal mechanism, presence of multiple input parameters and responses (outputs) and interactions among them and varying interest of different stakeholders with respect to relative importance assigned to the considered responses. Multi-criteria decision making (MCDM) techniques have become potent tools in solving parametric optimization problems of the EDM processes. In this paper, more than 130 research articles from SCOPUS database published during 2013–22 are reviewed extracting information with respect to experimental design plans employed, materials machined, dielectrics used, process parameters and responses considered and MCDM tools applied along with their integration with other mathematical techniques. A detailed analysis of those reviewed articles reveals that the past researchers have mostly preferred Taguchi’s L9 orthogonal array as the experimental design plan; EDM oil as the dielectric fluid; medium and high carbon steels as the work materials; peak current and pulse-on time as the input parameters; material removal rate, tool wear rate and surface roughness as the responses; and grey relational analysis as the MCDM tool during conducting and optimizing EDM operations. This review paper would act as a data repository to the future researchers in understanding the stochastic behaviour of EDM processes and providing guidance in setting the tentative operating levels of varying input parameters along with achievable response values. The extracted dataset can be treated as an input to any of the machine learning algorithms for subsequent development of appropriate prediction models. This review also outlines potential future research avenues, emphasizing advancements in EDM technology and the integration of innovative multi-criteria decision-making tools.