Calculation Principle Research Articles

Simulation study on the flow-induced vibration and noise in marine centrifugal pumps

Due to the three-dimensional non-axisymmetric shape of the volute, its interaction with the impeller increases the internal flow field complexity and instability of the marine centrifugal pump, representing the main reason for pump body vibration and hydraulic noise. First, the basic principle of fluid machinery noise calculation was explained based on the Lighthill acoustic analogy method and Curle’s theory. Then, the fluid pressure pulsation and flow characteristics of centrifugal pumps were analyzed using the Fluent software, after which the Actran software was used to examine the flow-induced vibration noise properties. The results showed that the clearance size significantly impacted the pump head, while the peak value of the flow-induced vibration response was mainly twice the blade frequency. Although a larger ring clearance increased the structural vibration, it had little impact on the sound pressure level changes in the external sound field. The results provided a new method for the structural optimization and low-noise design of marine centrifugal pumps.

A Knowledge Graph-Based Approach to Recommending Low-Carbon Construction Schemes of Bridges

With the development of the engineering construction industry, knowledge became an important strategic resource for construction enterprises, and knowledge graphs are an effective method for knowledge management. In the context of peak carbon dioxide emissions and carbon neutrality, low carbon emission became one of the important indicators for the selection of construction schemes, and knowledge management research related to low carbon construction must be performed. This study investigated a method of incorporating low-carbon construction knowledge into the bridge construction scheme knowledge graph construction process and proposed a bridge construction scheme recommendation method that considers carbon emission constraints based on the knowledge graph and similarity calculation. First, to solve the problem of the poor fitting effect of model parameters caused by less annotation of the corpus in the bridge construction field, an improved entity recognition model was proposed for low-resource conditions with limited data. A knowledge graph of low carbon construction schemes for bridges was constructed using a small sample dataset. Then, based on the construction of this knowledge graph, the entities and relationships related to construction schemes were obtained, and the comprehensive similarity of bridge construction schemes was calculated by combining the similarity calculation principle to realize the recommendation of bridge construction schemes under different constraints. Experiments on the constructed bridge low carbon construction scheme dataset showed that the proposed model achieved good accuracy with named entity recognition tasks. The comparative analysis with the construction scheme of the project verified the validity of the proposed construction scheme considering carbon emission constraints, which can provide support for the decision of the low-carbon construction scheme of bridges.

Efficiency and internationalization of mining and ­metallurgical groups of Ukraine

Purpose. Development of a structural and systemic approach to determining the effectiveness of the functioning and internationalization of the country’s mining and metallurgical industrial groups and the formation of their possible development vectors. Methodology. The results of the presented scientific research were obtained using general and special methods of cognition: abstract-logical analysis, systematization and combination, method of theoretical generalization, method of dialectical cognition, deduction and induction, statistical analysis, econometric method of trend formation. Findings. Approaches to the determination of performance indicators and the level of internationalization of mining and metallurgical industrial groups, which were dynamically formed in the modern conditions of the functioning of multinational companies, were systematized. Principles of calculation, system of indicators of efficiency and level of internationalization, which were chosen to evaluate the leading mining and metallurgical industrial groups of Ukraine, and methodical approaches to the calculation of performance indicators and evaluation of the level of internationalization were substantiated, and analytical conclusions were formulated. The forecast was made and the development vectors of the country’s leading mining and metallurgical industrial groups were established based on the econometric calculations. Originality. Structural and systemic approach was justified to measuring the efficiency of operation and the level of internationalization of mining and metallurgical industrial groups of Ukraine, which is built on the principle of hierarchy, includes logically consecutive stages and provides an opportunity to determine the actual development vectors of mining and metallurgical industrial groups of Ukraine based on the econometric trend. A close relationship was established (on the basis of the calculation of the coefficient of determination) of performance indicators and the level of internationalization of mining and metallurgical industrial groups of Ukraine with the time factor. At the specification stage, trends (parabolic, logarithmic, hyperbolic, linear ones) were selected, their parameters were estimated by the method of least squares. The statistical significance of the equation was tested using the coefficient of determination and Fisher’s test. Practical value. It consists in the possibility of using the results of the conducted research for scientific developments and practical activities. The feasibility of systematic use of performance indicators and the level of internationalization in the practical activities of the leading mining and metallurgical industrial groups of Ukraine has been proven. The structural and systemic approach, which is built on the principle of hierarchy, provides an opportunity to determine the current development vectors of the leading mining and metallurgical industrial groups of Ukraine .

ПРОПОЗИЦІЇ ЩОДО ЗМІНИ НАВАНТАЖЕННЯ НА МОСТИ

Introduction. Bridge DBN V.1.2-15:2009 «Loadings and impacts» is the document that raised the level of calculated traffic loadings on bridges and bring their values closer to the values of LM1 model of Eurocodes. But the characteristic loadings were remained at the old level, which violated the principles of reliability calculations, according to which the characteristic loadings should deviate from the average values by 5 standards at least. Problem statement. Estimated vehicle loadings of the AK model in DBN B.1.2-15:2009 in compare with LM1 model of Eurocode EN 1991-2 and the track model according to US AASHTO LRFD standards shows that there is a certain balance between them. The calculated loading according to the standards of Ukraine occupies an intermediate position between the standards of Europe and the United States. However, the level of characteristic loadings is almost twice lower in compare with in Eurocode. This is a significant drawback of DBN, because it reduces the level of reliability of calculations based on the second group of limit states. Purpose. The article is devoted to the search and analysis of proposals for loading changes. Materials and methods. The article provides proposals for changing some loading parameters of AK model in order to maintain the level of calculated loadings and increase the characteristic loadings for approaching LM1 EN 1991-2 model loading. Results. In general, the changes proposed in the article will make it possible to raise the level of reliability of calculations according to the II group of limit states to the level of reliability of Eurocodes; at the same time the characteristic values of forces are 20 % lower than the values of LM1 model (except for bridges with one lane); calculated values of forces are (8–10) % lower than the values from the LM1 model (except for bridges with one lane); to simplify the existing loading model and to exclude additional lanes of loadings, to exclude the installation of pairs of tandems when loading lines of supporting moments impact. Conclusions. In this article, we did not touch the issue of introducing a single weighted average reliability coefficient for all permanent loadings. The existing coefficients cannot be substantiated due to the lack of reliable coefficients of variation. Now, a reliability coefficient of 1.25 has been introduced for all self-weight loadings, except for the pavement. And for pavement the coefficients are 1.5 — if the bridge is outside the city and 2.0 — if the bridge is in the city. At one time this was justified by the fact that there were known cases when the pavement on city bridges was doubled during reconstruction of the streets. But now there are no such cases. And if we take 1.5 for the weight of the pavement and 1.25 for the other weight, then for the own weight of all bridge structures we can take the coefficient γf = 1.35.

Semiconducting nonperovskite ferroelectric oxynitride designed ab initio

The recent discovery of HfO2-based and nitride-based ferroelectrics that are compatible to the semiconductor manufacturing process has revitalized the field of ferroelectric-based nanoelectronics. Guided by a simple design principle of charge compensation and density functional theory calculations, we discover that HfO2-like mixed-anion materials, TaON and NbON, can crystallize in the polar Pca 2 1 phase with a strong thermodynamic driving force to adopt anion ordering spontaneously. Both oxynitrides possess large remnant polarization, low switching barriers, and unconventional negative piezoelectric effect, making them promising piezoelectrics and ferroelectrics. Distinct from HfO2 that has a wide bandgap, both TaON and NbON can absorb visible light and have high charge carrier mobilities, suitable for ferroelectric photovoltaic and photocatalytic applications. This class of multifunctional nonperovskite oxynitride containing economical and environmentally benign elements offers a platform to design and optimize high-performing ferroelectric semiconductors for integrated systems.

Relay Protection Setting Calculation of Power Transformer Based on ETAP

The conventional relay protection setting calculation method considers the internal interference of the transformer and obtains the setting value quickly, which leads to large harmonic interference of the transformer and affects the secondary setting calculation results. Therefore, the setting calculation method of the power transformer relay protection based on the Electrical Transient Analysis Program (ETAP) is designed. The harmonic transfer characteristics of the power transformer are extracted, and the harmonic interference of the power transformer is proposed. Then the ETAP software is adopted to establish the calculation principle of the power transformer relay protection setting and improve the calculation accuracy of the secondary setting. Through comparative experiments, it is verified that the second fixed value of the algorithm is close to the actual fixed value and can be applied to real life.

Effect of Structured Training Workshop on Nurses’ Drug Dosage Calculation Competence at Tertiary Care Hospitals of Faisalabad

Background: Drug administration is a major component of patient care provided by nurses at hospitals. Appropriate drug administration ensures patient safety, as incorrect or unsafe administration can result in adverse patient health and hospital outcomes. Drug dosage calculation errors are the most common, threatening patient safety, lengthening patients' hospital stay and increasing associated costs worldwide. Aim: To evaluate the effectiveness of structured training workshop at enhancing nurses’ competence in drug dosage calculations. Methods: One group pre-test post-test quasi-experimental study was conducted on a convenient sample of 73 staff nurses working at public tertiary care hospitals of Faisalabad, Pakistan. Staff nurses aged 21-60 years who provide direct patient care, were included in the study.The study duration spanned over 04 months from July to October 2020. A structured questionnaire was used for the pre-test and post-test competency level of nurses in drug dosage calculations. The study intervention consisted of a structured training workshop focusing on basic mathematical skills for drug dosage calculation using the correct mathematical formula for unit conversions and linking the correct dose to the patient case scenario. SPSS version 26 was used for with-in group analysis employing t-test statistics. Results: Pre-test results revealed common errors in the application of basic mathematical principles for drug concentration unit conversions and complex calculations involving patient-age, weight and other variables.Post-test results demonstrated a significant improvement in level of competence of participant nurses in this regard, indicated by significant difference (p-value 0.000). Structured training workshop was found effective in enhancing nurses’ competency level in drug dosage calculations. Practical implication Conclusion: Structured training improved nurses' ability to identify drug calculation errors, understand the use of the correct formula, and calculate drug dosage accurately. This study emphasizes the importance of structured education and training of nurses aimed at reducing medication errors and improving patient health and hospital outcomes. Keywords: Competence; Drug dosage calculation; Nurses; Quasi experimental study; Pakistan; Workshop.

Volume calculation methods of irregular stone artifacts based on 3D laser scanning technology

ABSTRACT The rapid development of three-dimensional digital mapping and information technology have made the information recording and conservation of stone cultural relics more and more accurate and efficient, and their mapping methods have become more and more diverse. This study takes the rockery of the Humble Administrator’s Garden as an example to propose three volume measurement methods of massive, irregular, and immovable stone artifacts. These solutions are based on point cloud data obtained by a handheld 3D laser scanner and then different algorithms are used to calculate the volume.The three calculation principles are as follows: the voxel method, the encapsulation method, and the improved slicing method. Finally, the advantages, disadvantages and applicability scenarios of existing conventional volume measurement methods for rockeries are also compared with these three methods. The measurement methods used in this study has significant advantages over conventional means of calculating the volume of rockery. It is of great significance for the information acquisition, conservation, restoration, and revitalization inheritance of the rockery.

Test Stand for Propellers and Rotors in VTOL Drone Systems

Abstract The paper proposes a stand that can be used for the testing of propellers and rotors with diameters up to 2.4 m, whose areas of application encompass, inter alia, vertical takeoff and landing (VTOL) type multi-rotor drone systems. The presented solution allows for testing propellers in systems with electric motors. To a certain extent, it is possible to achieve an increase in the measuring range by changing electric motors, power supply systems and measuring sensors. The paper presents several solutions for test stands that can be applied in the testing of propeller parameters, and commercially available propellers have also been deployed in the testing routines. The paper briefly presents the concept of the stand and its design, as well as the principle of operation and structural calculations underlying its functioning, after which the numerical model of the test stand is explained. The article then demonstrates the particular results of the test stand model’s functioning using the EMRAX 188 electric motor and two propellers, namely a commercial Aerobat propeller and a composite propeller designed and manufactured at the Łukasiewicz – Institute of Aviation. Thus, the paper presents both the theoretical results that follow from the model and the results of experimental research.

Research on seismic analysis methods of large and complex underground pipe structures in hard rock sites

In order to study the seismic design methods of large and complex underground pipe structures (LCUP) in hard rock sites, firstly, the structural characteristics of LCUP and the calculation principles of four typical seismic analysis methods were carefully sorted out. Secondly, based on different seismic analysis methods, the deformation and internal force response of three representative pipes were studied in detail, and the calculation accuracy and error causes of each seismic analysis method were analyzed. Finally, the advantages, disadvantages and applicability of the seismic analysis methods on typical pipes were systematically explained, and the technical route for seismic design of LCUP was proposed. The results showed that both the reaction displacement method and the reaction acceleration method can effectively analyze the seismic performance of standard section structures. The three-dimensional time-history analysis method was comprehensive and highly accurate for seismic analysis of complex spatial cross-node structures. The rigid connections of different pipes leaded to serious discontinuities in stiffness at the intersection, and the deformation and bending moment distributions were highly concentrated at the height away from the intersection. The influence range of the intersection was about three times the width of the intersection, and LCUP was classified according to this influence range. For standard section structures, seismic analysis should be carried out using the reaction acceleration method or reaction displacement method, while for spatial cross-node structures, three-dimensional time-history analysis should be used for seismic analysis. This scientific seismic design method achieved multiple optimal balances of seismic safety, analysis accuracy, efficiency and economy in the seismic analysis of large and complex underground structures. A theoretical basis and useful reference for the scientific design, accurate prediction and seismic safety evaluation of seismic response of LCUP were provided in this paper.

Energy evolution of concrete with cold joint under the action of sulfate dry-wet cycles with loading

To investigate the erosion and damage mechanism of concrete with cold joint in the cold and arid saline environment of western China, the energy evolution of concrete with cold joint under the action of sulfate dry–wet cycles was analyzed and produced concrete with cold joint at different pouring intervals. Based on uniaxial compression experiments and microscopic tests, the effect of sulfate dry–wet cycles on the strength and energy evolution pattern of concrete with cold joint is investigated and analyzed by means of energy calculation principles. Results show that the strength of concrete with cold joint, as well as the elastic strain and dissipation energies at the damage and peak stresses, tend to increase and then decrease with the increment of the number of sulfate dry–wet cycles. And a declining trend is observed as the interval between new and old concrete pours increases. Kad can be used as an early warning indicator for concrete damage by defining the ratio of the elastic strain energy Uade at the damage stress to the elastic strain energy Uae at the peak stress as the energy storage level Kad at the damage stress of concrete with cold joint. With the increase in the number of sulfate dry–wet cycles, the level of energy storage at the damage stress Kad first increases and then decreases. The concrete with cold joint first exhibits damage difficulty and then ease, that is, the higher the level of energy storage at the damage stress Kad is, the stronger the ability of concrete with cold joint to resist damage will be.

Calibration methods and uncertainties estimation of WEST infrared thermography diagnostics

This paper presents the method toward quantifying the global uncertainty on the blackbody temperature measurement from the infrared (IR) diagnostics of WEST. To address this goal, the main functional elements of the IR diagnostics are identified. Then the temperature calibration and calculation principles are presented and analysed to extract the main potential uncertainty contributors, such as the optical transmission coefficients and their stray lights, or the accuracy of temperature references used for calibration. These contributors are individually estimated, or experimentally measured when a supposed effect on the overall uncertainty is identified, like environmental conditions or parasitic radiations. In particular, effects of environmental temperature on the transmission lines and camera is thoroughly studied. All contributions are then aggregated in the uncertainty propagation calculation and results in an overall temperature uncertainty versus the temperature estimation. The uncertainty is in the range of 5–10% for blackbody temperatures above 200 °C, and progressively worsens when temperature decreases.

Hypothetical interventions on risk factors for depression among middle-aged and older community-dwellers in China: An application of the parametric g-formula in a longitudinal study

BackgroundSleep disturbances, frailty, and body pain are widespread in middle-aged and older adults with depression, and have been identified as depression risk factors. However, there is a scarcity of research on the benefits of sleep improvement, frailty amelioration, and pain management on incident depression. MethodsA total of 8895 respondents aged above 45 years were derived from the China Health and Retirement Longitudinal Study (CHARLS) between 2011 and 2018. The parametric g-formula was used to estimate the 7-year risks of depression under independent hypothetical interventions on nighttime sleep duration (NSD), daytime napping duration (DND), perceived sleep quality (PSQ), frailty, and pain, as well as their various combinations. ResultsThe observed depression risk was 41.77 %. The independent intervention on frailty was the most effective in lowering incident depression, with a risk ratio (RR) of 0.61 (95 % CI: 0.57–0.64), followed by PSQ (RR: 0.75, 95 % CI: 0.73–0.78), pain (RR: 0.90, 95 % CI: 0.87–0.91), and NSD (RR: 0.96, 95 % CI: 0.93–0.98). In subgroup analysis, intervention on NSD was more effective in men, PSQ was more effective in middle-aged individuals, and frailty and pain were more effective in older persons. The combined intervention of NSD, PSQ, frailty, and pain lowered the risk the greatest (RR: 0.35, 95 % CI: 0.32–0.37). LimitationsGeneralizing our results to other populations should be possible if they have the same distribution of effect modifiers and interference patterns because of the calculation principle of the parametric g-formula. ConclusionsInterventions for sleep disturbances, frailty, and body pain can minimize the risk of depression.

Short Circuit Current Algorithm and Software Design Based on IEC60909 Standard

With the continuous growth of load and the enhancement of grid structure, the problem of excessive short circuit current has become a key factor affecting the safe operation of the China Southern Power Grid. The comparison of measured data shows that the short circuit current calculation results of China Southern Power Grid are optimistic based on the existing short circuit current calculation method. It brings difficulties to the arrangement of the power grid operation mode. This paper first briefly introduces the calculation principle of the IEC60909 Standard (short for IEC60909 Short Circuit Current Calculation Standard). And based on this standard, an improved algorithm for short-circuit current calculation is proposed. FCAP (short for Fault Current Analysis Program), a newly developed software based on the improved algorithm, is compared with other similar software being popular in domestic and foreign to prove its engineering practical value.

Design Optimization of Two Diagonal Slotted Block Horn for Ultrasonic Plastic Welding

One of the inescapable techniques which are widely used in different engineering fields and manufacturing industry is ultrasonic plastic welding. It is recommended to make the design of the main components of ultrasonic technique to have high precision and good accuracy. Ultrasonic horn remains the main components, as this part is always working contact to the working area. Therefore, design and optimization of this tool become more essential due to large number of application. In this research a horn type block contain two slots was successfully designed and its dimensions were precisely optimized utilising from the principles of ANSYS finite element software package, theoretical calculation and mathematical analysis expression in order to conduct the requirements application of plastic welding. The three dimensional model analysis of the block horn was carried out to identified from many criteria such as allow the horn to vibrate in purely longitudinal manner relative to the frequency excitation of generator, normally 20 kHz, obtained acceptable tuning mode and avoidance from participating with other non tuned flexural and torsional modes, insure high sufficient displacement amplitude at working area and low stress concentration shift close to the area of zero deformation, getting high surface uniformity at block horn tip and ensure the horn having acceptable gain. High amplification of block horn with configuration of two slots was calculated using modal and harmonic analyses of simulation models, while optimization of designed horn was done through performing response surface methodology (RSM) matrix obtained from MINITAB software and further connected with genetic algorithm (GA) by aid using of MATLAB software code. The results inferred that good estimation and prediction of vibration amplitude for the exciting slotted block horn can help to ensure sufficient amount of energy delivered to the working area for any application referred to plastic welding.

Occupant-centric dynamic heating and cooling loads simplified prediction model for urban community at energy planning stage

Simplified and accurate prediction of dynamic heating and cooling loads is the basis for urban energy planning and optimal operation of integrated urban energy systems. Majority existed urban community heating and cooling loads prediction models focus on the effects of building physics, weather conditions, and construction features, barely consider the impact of occupant presence rate, operating schedule, and internal heat gain on heating and cooling loads, which affects the prediction accuracy. Thus, aiming to get the balance of simplification and accuracy, an occupant-centric prediction model of dynamic heating and cooling loads for urban community at energy planning stage with simplified calculation principles, reduced input parameters, improved simulation accuracy, and preserved characteristics of the individual building in the community was proposed. Based on the previously developed building envelope simplification model, internal heat gain modules and operating schedule modules were developed. After verifying the prediction accuracy of the model by comparison with EnergyPlus software, the model was applied to a typical university campus. Case study analysis shows that this model can accurately predict dynamic space heating and cooling loads of urban community with simplified inputs at energy planning stage, which provides theoretical support and convenience for optimizing the urban energy prediction model.

Determination of flow rate and velocity of fluids in a non-pressurized pipeline

This article discusses the importance and principles of hydraulic calculations in in non-pressurized pipelines. The main hydraulic elements of flow in a non-pressurized pipe are determined depending on the radius of the pipe. The most efficient hydraulic cross section R=f(h) for fluid flow in a non-pressurized pipe was scientifically substantiated for the depth and diameter of the flow through a functional relationship.

Algorithm for accounting for the cost of International freight transportation: influencing factors and information support

The article describes the peculiarities of accounting for the cost of international freight transportation. The purpose of the article is to generalize the cost accounting experience and develop proposals for improving the pricing algorithm under different conditions. The results of the study are based on questionnaire data of 20 enterprises and entrepreneurs-carriers of the Volyn region, whose main type of service is international transportation. Most of them (18 out of 20 enterprises) belong to the general classification of micro- and small enterprises, which characterizes this business as small, 2 enterprises belong to the average in terms of the number of employees and the currency of the balance sheet. For the purpose of research, they were divided into 3 groups: small (0–10 employees), medium (11–20 employees), large (21–30 employees). In order to study the peculiarities of cost formation, their distribution was carried out by the number of cars, as this affects the number of transportations. The main principles of formation and calculation of the cost of freight transportation, types of cost of freight transportation, composition of cost items that form the cost of transportation are considered. The main influencing factors that led to changes in the cost of road transportation are characterized: the influence of military actions, the influence of the size of the enterprise, the influence of the volume of work performed by a unit of motor vehicles. According to the results of the assessment of the factors affecting the cost of road transportation, it was established that the share of production costs decreases with the increase in the size of the enterprise, while the share of general production and other costs increases, that is, micro-enterprises are more flexible.

ANÁLISE DO APRENDIZADO PROFUNDO NOS IMPACTOS RESULTANTES DOS TREINOS SEMANAIS DE CARGA SOBRE O SISTEMA BIOLÓGICO DOS ESTUDANTES

ABSTRACT Introduction The recent development of the deep learning algorithm as a new multilayer network machine learning algorithm has reduced the problem of traditional training algorithms easily falling into minimal places, becoming a recent direction in the learning field. Objective Design and validate an artificial intelligence model for deep learning of the resulting impacts of weekly load training on students’ biological system. Methods According to the physiological and biochemical indices of athletes in the training process, this paper analyzes the actual data of athletes’ training load in the annual preparation period. The characteristics of athletes’ training load in the preparation period were discussed. The value, significance, composition factors, arrangement principle and method of calculation, and determination of weekly load density using the deep learning algorithm are discussed. Results The results showed that the daily 24-hour random sampling load was moderate intensity, low and high-intensity training, and enhanced the physical-motor system and neural reactivity. Conclusion The research shows that there can be two activities of “teaching” and “training” in physical education and sports training. The sports biology monitoring research proves to be a growth point of sports training research with great potential for expansion for future research. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

A characterization of progressively equivalent probability measures preserving the structure of a compound mixed renewal process

Generalizing earlier works of Delbaen & Haezendonck [5] as well as of [18] and [16] for given compound mixed renewal process S under a probability measure P, we characterize all those probability measures Q on the domain of P such that Q and P are progressively equivalent and S remains a compound mixed renewal process under Q with improved properties. As a consequence, we prove that any compound mixed renewal process can be converted into a compound mixed Poisson process through a change of measures. Applications related to the ruin problem and to the computation of premium calculation principles in an insurance market without arbitrage opportunities are discussed in [26] and [27], respectively.