Journal of Mechatronics and Artificial Intelligence in Engineering
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Preparation and properties of polyamide elastomers by a new synthesis route of Michael addition reaction
Get PDFAt present, the mainstream industrial synthesis method of polyamide is still bulk fusion polymerization, which is not in line with the concept of green synthesis because of the high threshold of reaction conditions and large energy consumption. Based on this, a new synthesis route of polyamide elastomer was studied in this paper. By synthesizing the end-functionalized long carbon chain diacrylamide (DDA) containing amide bonds, the synthesis mechanism was made by the thiol double bond Michael addition reaction. A series of polyamide elastomers with different ratios of hard and soft segments were synthesized by using dimercaptan chain extenders with different molecular weights. The results showed that the new synthesis route successfully prepared DDA and polyamide elastomers. The mechanical properties of the products were excellent, and the strain rate could reach 383 %. Tensile strength up to 23.08 MPa. The synthesis route has the characteristics of simple reaction process, mild reaction conditions and high reaction conversion rate. It provides theoretical guidance for the new synthesis route of polyamide elastomer
Research on quantitative design methods for the durability of reinforced concrete structures in a hot ocean environment
Get PDFThis paper establishes a quantitative design method for the durability of concrete structures in cross-sea bridges through investigation, rapid chloride migration coefficient method (RCM) and theoretical calculation, considering the impact of temperature on chloride ion diffusion rates in a hot marine salt erosion environment. Combined with the RCM test and bridge service data, a quantitative design method for bridge concrete durability is proposed. Test results show that the growth rate of the chloride ion diffusion coefficient of concrete is approximately 1.028 for every 1 °C increase. For every 5 °C increase, the growth rate of the chloride diffusion coefficient of concrete is about 1.15, and the cover depth of the concrete structure should be multiplied by a coefficient of 1.07. Therefore, the concrete cover depth should be appropriately increased, considering the influence of ambient temperature. Furthermore, fly ash, slag, and stone powder can increase the concrete’s resistance to chloride corrosion. When the influence of temperature on the chloride ion diffusion coefficient is considered, the durability design of the concrete structure of the sea-crossing bridge is conducted, which is beneficial for ensuring their service life
Numerical study on sloshing in coaxial shells
Get PDFSloshing in coaxial shells partially filled with liquid is investigated using reduced boundary element method. Conical shells are considered as storage tanks. An ideal and incompressible fluid is assumed in the shells. The spectral boundary problem for the liquid vibrations in rigid shells is solved. The results demonstrate the high accuracy of the presented approach
A study into the fluid power control characteristics of a hydrostatic transmission for mobile machinery
Get PDFIn response to improve the quality and level of hydrostatic transmission (HST) products for modern mobile machineries, the closed-loop transfer functions of a HST are established by mathematical modeling, a comprehensive testing equipment is developed employing a proportional relief valve for automatic program loading and fuzzy-PID oil temperature control, the testing equipment is capable of conducting various performance tests for various models of HST integrated pump-motor products, including factory and type tests, especially continuous impact and endurance performance tests under high temperature and high-speed conditions. Comprehensive performance test of the above test sample is carried out using the developed equipment, that the test results agree well with the previous simulation results verifies the correctness of the established theoretical analysis model. The obtained theory and equipment from this work provide theoretical and experimental technical support for improving design and development of high-end fluid components for modern mobile machinery HST
Problems of rutting on asphalt pavements
Get PDFIn the article, under field conditions (on the lane of a city road for public transport), using modeling and traffic flow analysis methods, the formation of ruts on an asphalt concrete pavement is studied. The maximum total rut depth on the road section under consideration reaches 110 mm. 715 buses and 25 trucks pass along a separate lane of the road per day, the relative rutting impact of which is from 5.68 to 16.41 compared to the design vehicle. The design of the road pavement on the experimental section with a total thickness of 48 cm is too weak for the actual traffic flow, which was the main reason for the premature failure of the road due to unacceptable rut sizes on the asphalt concrete pavement
Improving piano music signal recognition through enhanced frequency domain analysis
Get PDFFeature extraction is a crucial component in the analysis of piano music signals. This article introduced three methods for feature extraction based on frequency domain analysis, namely short-time Fourier transform (STFT), linear predictive cepstral coefficient (LPCC), and Mel-frequency cepstral coefficient (MFCC). An improvement was then made to the MFCC. The inverse MFCC (IMFCC) was combined with mid-frequency MFCC (MidMFCC). The Fisher criterion was used to select the 12-order parameters with the maximum Fisher ratio, which were combined into the F-MFCC feature for recognizing 88 single piano notes through a support vector machine. The results indicated that when compared with the STFT and LPCC, the MFCC exhibited superior performance in recognizing piano music signals, with an accuracy rate of 78.03 % and an F1 value of 85.92 %. Nevertheless, the proposed F-MFCC achieved a remarkable accuracy rate of 90.91 %, representing a substantial improvement by 12.88 % over the MFCC alone. These findings provide evidence for the effectiveness of the designed F-MFCC feature for piano music signal recognition as well as its potential application in practical music signal analysis
Natural resources can help reducing cardiovascular risk: randomized controlled study
Get PDFCardiovascular diseases are the leading cause of death globally accounting for 32 % of all global deaths. Addressing modifiable risk factors, including hypertension and stress, remains paramount in the prevention of CVD. This study aimed to assess the impact of the balneotherapy on blood pressure, heart rate, electrocardiogram parameters, utilization of antihypertensive medications, and stress levels. Methodology. Multicenter randomized controlled single-blind parallel group trial was made in 6 Lithuania resort centers. 373 participants with the stress level > 3 (10, VAS) randomly divided into 6 groups in two clusters for receiving a 6- or 11-day complex treatment using natural resources – mineral waters, peloids, salt, nature therapy; follow-up period was 6 months. The BP, HR, ECG, stress level and other parameters were analyzed in 131 participants who passed a full course of investigation. Results. The significant reduction of systolic blood pressure after treatment (7.8 mmHg) and during 6 months (7.3 mmHg) together with diastolic 5.5 after 6 month and heart rate (4 b/min) was achieved in 11-day ambulatory balneotherapy group. Increase in the activity of the parasympathetic nervous system was observed, which is reflected by an increase in the duration of the ECG indicators. The stress level decreased by up to 43%, and stress management improved by up to 41% following inpatient treatment. Conclusion. Therapy using natural resources could stand for additional cardiovascular disease prevention and management method in integrative therapy
Interconnections between local Schumann resonances and episodes of kidney disease
Get PDFThe aim of the study was to evaluate the interconnections between local Schumann resonances of the Earth’s magnetic field and episodes of kidney disease. Materials and Methods: Study participants included 716 males and 624 females who had episodes of kidney disease during the period of 1 January 2021 to 31 December 2021 and attended the Department of Nephrology at the Hospital of Lithuanian University of Health Sciences, Kauno klinikos. Time varying magnetic field data was collected at the magnetometer site located in Lithuania. Results and Conclusions: The study results support the hypothesis that the Earth’s magnetic field has a relationship between the number of nephrology patient hospitalizations per week and the average weekly local Schumann resonances strength in different frequency ranges. Working hypotheses are proposed for the mechanisms of the influence of the Earth’s electromagnetic field on kidney function: а) quantum mechanical features of the atomic composition of renal tissue molecules determine a kidney-specific reaction; b) cyclotron resonance mechanism; c) resonant response of cells of morphological structures of kidney tissue to external bioactive frequencies in the range of 6-8 Hz; d) mechanism of indirect influence of blood as a magnetically saturated medium
A review on positioning techniques of mobile robots
Get PDFIn this article, we have reviewed the available positioning, localization and navigation techniques for mobile robots. Different localization techniques based on diverse technologies are compared with one another, along with diverse algorithms and techniques for analyzing this information. The article highlights algorithms based on odometry, triangulation, visual analysis, and marker detection. The analysis included global, local, and personal location. One acquires knowledge on which method is suitable for indoor use and which for outdoor use, as well as the appropriate environmental conditions for each. The accuracy of the individual methods was compared with that of integrated systems consisting of several methods. For practical knowledge, it is possible to determine whether a particular method is cost-effective for a particular solution and to compare the expenses involved
Adoption of metal additive manufacturing in nnpc limited: current state and challenges
Get PDFMetal additive manufacturing has emerged as a promising technology with vast potential in the oil and gas industry. The Nigerian National Petroleum Company (NNPC) Limited recognizes the significance of this technology and has initiated efforts to adopt metal additive manufacturing within its operations. This paper aims to provide an overview of the current state of metal additive manufacturing in the NNPC and highlight the challenges faced during its adoption process. The study goes on further to suggest strategies and future directions to ensure successful company-wide and industry-wide adoption and acceptance