Structural Scheme Research Articles

Axial deformation of early-age concrete-filled steel tubular columns under multi-stage loading

The continuous construction scheme for concrete-filled steel tubular structures in practice is time-saving and cost-effective in comparison to the conventional moulding construction methods, whilst this also results in complex stress conditions and working mechanisms in the early-age concrete-filled steel tubes (CFSTs) during construction. This investigation aims to explore the influence of continuous construction process on the axial compressive behaviour of early-age CFSTs as subject to multi-stage loading schemes. Eight short square early-age CFST columns are designed and tested. The axial deformation evolutions of CFSTs are analyzed for different load parameters including the initial stress of steel tube, loading time interval and load magnitude. The test results show that the deformation of early-age CFSTs varies significantly with various load parameters. Excessive deformation can be observed during the multi-stage loadings due to the local buckling of the steel tube. Based on the shrinkage and creep model of concrete, a theoretical algorithm for calculating the relationship between the deformation of early-age CFST and the age of concrete is developed. Furthermore, a simplified calculation method for the deformation of early-age CFST under multi-stage loading is proposed that can realistically describe the deformation of early-age CFSTs under continuous construction process. The research findings lay a foundation for the deformation control and safety assessment of CFST under continuous construction scheme.

Active power decoupling scheme of symmetrical LCL structure in single‐phase grid‐connected voltage source inverter for ultra‐high voltage transmission

SummaryThe voltage source converter (VSC) is an important component of ultra‐high voltage (UHV) technology, where the former is responsible for converting new energy sources into electricity and the latter enables the transmission of electricity over long distances. However, the VSC has a serious problem of oscillation power under three‐phase unbalance, which comes from the single‐phase voltage source inverter (VSI) that is the basic structure of VSC. So there is always the requirement for active power decoupling (APD). Conventional passive solutions increase the overall size significantly, and existing active solutions either require the addition of a decoupling topology or rely strongly on their own original topology and more complex control. To overcome this drawback, this paper proposes an improved APD method with a combination of topology‐type and control‐type decoupling features for single‐phase VSI based on the symmetrical LCL filter for solving the power oscillation problem of VSC at the source. The proposed structure can decrease common mode interference and can absorb the oscillation power by the original filter capacitors of the LCL filter. Besides, the original circuit components can be reused, and the decoupling is simple enough to achieve APD without affecting the full bridge control. Next, the control is optimized to reduce the compensation error and input voltage. Finally, the experimental device is carried out to verify the effectiveness of the proposed method.

Analytical support for identification trends and problems in the development of interaction between stakeholders of education, science and business

Ukraine’s entry into the path of innovative economic development requires modernisation of the interaction between stakeholders of education, science and business to create a network of cooperation, taking into account the needs of stakeholders due to the situation in Ukraine as of 2023, focusing on changes in the world economy. The purpose of the article was to build a structural and logical scheme of analytical support for identifying trends and problems in the development of interaction between stakeholders in education, science and business. The methodology was based on the use of logical, systemic and comparative analysis. The analysis of budgetary funding for priority areas of innovation activity and sales of innovative products (services) and new technologies by budgetary funds managers showed no trends and priorities for the development of technology transfer and other intellectual property rights carried out by universities, research institutions, enterprises and organisations. The generalisation of changes and prospects of legislative regulation of support for educational, innovative, scientific and technical activities of business focuses on post-war reconstruction, which involves increasing confidence in the educational, scientific and expert activities of institutions for their effective functioning and increasing the volume of research funding. The analysis of the integration aspects of the research and innovation system into the European Research Area and support from international scientific organisations and foreign governments proved the support received from many national scientific communities and international scientific organisations in the creation of the portal for international scientific and technical cooperation and the international consortium for infrastructure and research. The practical significance of the study lies in the proposed directions for improving interaction with business of educational and scientific institutions in the process of implementing innovations separately by stages of interaction with stakeholders (attraction, financing and implementation)

Multi-objective optimization design of coupled wall structure with hybrid coupling beams using hybrid machine learning algorithms

A new hybrid coupling beam incorporating buckling restrained energy dissipaters and viscous dampers was previously recommended. The beam can effectively reduce the floor acceleration and interstory drift ratio of coupled wall structure, and has great application prospects. However, the optimal design of a structure with hybrid coupling beams needs to consider multiple objectives, and these objectives often conflict with each other. At the same time, multiple parameters need to be optimized, resulting in a corresponding increase in the time-cost. This usually brings challenges to structural design. To address this issue, this study presents a hybrid intelligent optimization framework based on multi-objective particle swarm optimization (MOPSO) and machine learning techniques. The developed framework uses machine learning technology to quickly predict the seismic performance of structures with hybrid coupling beams, and obtain a design solution set through multi-objective particle swarm optimization. The proposed framework is demonstrated by considering a case study of a 12-story coupled wall structure with hybrid coupling beams, and it is shown that compared with the initial stage of optimization, the seismic performance of optimized structure is simultaneously improved at close cost. The floor acceleration and interstory drift ratio of the optimized structure are reduced by 11.5% and 38.7%, respectively. Finally, a formula is proposed to quantify the optimization result of pareto solution, so as to make an optimal structural design scheme. In practice, the proposed framework can provide guidance for realizing rapid and accurate about multi-objective optimization of the coupled wall structure with hybrid coupling beams.

Power Flow Management of Interconnected AC Microgrids Using Back-to-Back Converters

Microgrids have limited renewable energy source (RES) capacity, which can only supply a limited amount of load. Multiple microgrids can be interconnected to enhance power system availability, stability, reserve capacity, and control flexibility. This paper proposes a novel structure and control scheme for interconnecting multiple standalone microgrids to a common alternating current (AC) bus using back-to-back converters. The paper presents a high-level global droop controller that exchanges power between interconnected microgrids. Each microgrid considered in this paper comprises RES, battery, auxiliary unit, and load. The battery maintains the AC bus voltage and frequency and balances the difference in power generated by the RES and that consumed by the load. Each microgrid battery’s charge/discharge is maintained within the safest operating limit to maximize the RES power utilization. To achieve balance and continuity of supply, renewable power curtailment and auxiliary power supplement mechanism is designed based on the bus frequency signalling technique. Performance evaluation shows that the proposed controller maximizes renewable power utilization and minimizes auxiliary power usage while providing better load support. The performance validation of the proposed structure and control strategy has been tested using MATLAB/Simulink.

Introduction of Environmental Monitoring for the Sustainable Development of the Agro-Industrial Complex: The Method of the Genuine Savings Index

Objective: The purpose of the study is to conduct a theoretical and methodological analysis of environmental monitoring both at the global and agro-industrial organizational levels. The article highlights the important problems associated with the anthropogenic impact of agro-industrial organizations on the environment and the need to balance development with environmental sustainability. Methods: The study uses various methods, including monographic, economic-statistical, balance, economic modeling, and comparison. Along with this, the study analyzes the reports on the Environmental Performance Index (EPI) prepared by Yale and Columbia Universities, as well as an original methodology for calculating the genuine savings index at the organizational level. Results: The content of the EPI is disclosed, and its dynamics over the past ten years for key economically developed countries are shown. A structural scheme of environmental monitoring is developed and substantiated, specially designed for agro-industrial organizations and firmly based on an environmentally oriented accounting and analytical system. Conclusion: The original methodology for determining the genuine savings index of agricultural organizations is presented. An organization’s genuine savings index is determined and assessed based on the developed analytical map.

PROBLEMS OF THE PROCESS OF LIQUIDATION OF EXTRAORDINARY SITUATIONS AT THE REGIONAL LEVEL UNDER THE CONDITIONS OF MILITARY INFLUENCE ON THE SYSTEM OF TRAINING SPECIALISTS IN THE OPERATION OF EMERGENCY AND RESCUE EQUIPMENT

The work examines the field of problems of training specialists in the operation of emergency and rescue equipment in the conditions of uncertainty of the process of receiving and modernizing the latter. During the hostilities, the system of training specialists of the State Emergency Service faced a number of challenges that significantly affected the quality of knowledge and skills that graduates of higher education institutions receive. If the problem of the issue is considered only in the part of the training of specialists in the operation of emergency and rescue equipment, then the following should be noted. A stable structural and logical scheme of the process of coordination and improvement of the efficiency of the system of training specialists in the operation of emergency and rescue equipment provides for the presence of a mandatory procedure for the coordination of operational and technical parameters of emergency and rescue equipment and the methodology of training specialists in its operation. It has been proven that today there is a range of additional tasks related to both the organization of material support of units of the State Emergency Service and the process of training and retraining of specialists in the operation of equipment and technical means. In order to comprehensively solve the mentioned issues, it is necessary to form an effective methodology for provision and training, taking into account the experience of domestic and international researchers and the principles and criteria of NATO. A structural and logical scheme of the methodology for increasing the effectiveness of the process of preventing emergency situations in conditions of uncertainty of the parameters of the training of specialists and the operation of emergency rescue equipment has been formed, which consists of 6 procedures, the application of which is limited to the field of regional conditions for the use of emergency rescue equipment and are related to each other directly and feedback, which in the end allows to further unify the process of training specialists taking into account experience and NATO standards. Keywords: structural and logical scheme, operation, emergency rescue equipment, emergency situation, training of specialists.

Multi-objective optimization decision-making of an underwater vehicle rotary docking skirt structure

This study determines the design parameters, analysis methods, and mesh size of a finite-element analysis model in the structural design of a rotary docking skirt (RDS) structure for an underwater vehicle. The impact of the structural design variables on the response is then studied. The sample points determined using the optimal Latin hypercube method are analyzed and fitted with the Kriging model, response surface model, and radial basis function. After comparing the fitting accuracies of the three approximation models, an approximation model of the RDS structure is determined. Next, several typical multi-objective optimization algorithms are tested and the improved nondominated sorting genetic algorithm II (INSGA-II) is selected for establishing an optimization model of the RDS structure. INSGA-II obtains the Pareto solution set of multi-objective optimization. The weights are obtained by combining the subjective and objective weights determined through the subjective-weighting analytic hierarchy process and the objective-weighting entropy weight method, respectively. Based on the combination weight, the technique for order preference by similarity to the ideal solution method is selected for multi-objective optimization decision-making. The final decision-making scheme of the rotary docking skirt structure improved the optimization effect compared to the initial scheme.

Theory of Plastic Mechanism Control for Linked Column Frames

AbstractThe main purpose of this work is to define a design procedure for dissipative replaceable link frames (LCFs). These structural schemes are characterized by the columns connected with link elements representing the plastic zones of the structure and, consequently, they assure the maximum dissipation of seismic energy in input. The design rules, proposed in this paper, are based on the Theory of Plastic Mechanism Control (TPMC). This procedure is based on the extension of the kinematic theorem of limit analysis to the concept of the equilibrium curves of the failure mechanisms and it guarantees the achievement of the global collapse mechanism under severe seismic actions. In order to evaluate the accuracy of this procedure, a case study is presented. In particular, a LCF with four storeys and three bays is designed by means of the proposed design rules. Finally, the same steel frame is implemented in SAP2000 program, and a pushover analysis is performed to evaluate the ultimate behaviour of the modelled structure.

Novel Paradigm for Steel Joints in Gridshell Structures: from Structural Optimization to Advanced Construction

AbstractNovel integrated computer‐aided paradigm/workflow for the topology optimization (TO) and additive manufacturing (AM) of steel joints in gridshell structures is proposed. The architecture scheme of gridshell structure was first established and numerically analyzed through Grasshopper parametric platform. Based on the extracted joint geometric parameters and the corresponding loading conditions, the initial joint structures were parametrically modelled using the subdivision surface method. Further parametric TO design was accomplished by the bi‐directional evolutionary structural optimization (BESO) method on the basis of cloud computing server. A series of mesh smoothing and reverse modelling algorithms were applied to the optimized joint to obtain a closed smooth surface in the NURBS form, which was then output as STL file for additive manufacturing. One typical optimized joint was additively manufactured using selective laser melting. The proposed workflow can be extended to a much wider range of spatial structures with various joint types.

Noise robustness of an operational modal-based structural damage-detection scheme using impact-synchronous modal analysis

Noise robustness of an operational modal-based structural damage-detection scheme using impact-synchronous modal analysis

Parallel adder-subtractor on elements of neural logic

Modern universal computing machines are capable of implementing any algorithm, but when solving certain tasks in terms of processing speed, they cannot compete with specialized computing modules that can increase the speed of performing arithmetic operations by using parallelism in data processing. The reliability of arithmetic calculators increases due to the use of neural-like elements. Specialized devices effectively solve array processing tasks, artificial intelligence tasks, and are used as control devices. The developed structure of a parallel adder-subtractor based on neural logic elements ensures high performance and reliability. The structural and functional schemes of the adder/subtractor blocks allow to increase the speed in comparison with the known sequential action adder when added in additional codes by at least 2 times, and with a parallel adder with sequential transfer by at least 1.5 times. It is shown that the hardware complexity of the presented adder-subtractor is 1.3 times lower compared to the sequential action adder and 2.8 times lower compared to the parallel adder with sequential transfer. The proposed structure of the adder-subtractor provides an increase in the calculation speed of arithmetic operations due to the implementation of parallelism in data processing.

Development of a Variable-Configuration Bionic Robotic Fish.

Bionic robotic fish have advantages over traditional underwater propulsion. Most of the existing studies have been conducted with only one type of fish as a bionic object, but a single propulsion mode may not be able to achieve the different needs of underwater operations. In this paper, we designed a pneumatic variable-configuration soft bionic fish and completed the overall structure design. It was built with a cownose ray as the main-configuration bionic object and a Caranx melampygus as the secondary-configuration bionic object. The base structure, actuators, and variable-configuration modules of the robot were made using flexible materials. After completing the design of the structure and control system of the robot, the prototype was manufactured and an underwater test was completed. The tests results indicated that the robot fish could achieve underwater linear propulsion and turning movements in both configurations. The maximum propulsion speed of the main configuration was 38.24 mm/s and the turning angle speed was 5.6°/s, and the maximum propulsion speed of its secondary configuration was 43.05 mm/s and the turning angle speed was 30°/s. The feasibility of the machine fish structure and control scheme were verified.

NEW VIBRATION DAMPING DEVICES FOR TUNNING TOOLS

The article provides a classification of vibration damping devices used in the processing of parts on metal-cutting machines. The structural scheme of an adaptive vibrating panel is considered and new designs of adaptive and adjustable spring-hydraulic vibration dampers designed for installation on turnings cutters are desceribed. A new type of vibration dampers with permanent magnets instead of springs and with a programmable frequency of natural oscillations, oriented to use in CNC machines, is proposed. Prospects for further improvement of vibration damping devices during machine operation are outlined.

Study of the theoretical basis of definition "social responsibility" of business entities

Introduction. At the time of introduction of innovative measures for the development of production processes, the impact of catastrophes, the COVID-19 pandemics, military conflicts, the rise in unemployment and inflation, the most important duty of the state is the construction of a socially oriented economy. To do this, it is necessary to create an effective system of management of social responsibility of economic entities, which include enterprises, as the main links of the economy of the country, regions, state. Businesses are responsible for the status and health of both employees of the company and residents of regions and countries where they carry out their economic activities. Materials and methods. On the basis of the structural and logical scheme, the chain of concepts is analyzed: social risks-social consequences-social alienation-social protection-social support. The purpose of paper is to determine the essence of terminology, which is the preliminary and is the basis of the primary theoretical basis, which determines the problem of the expediency of forming a system of social responsibility of economic entities. The task is to build a chain of applying concepts on the theoretical basis of the category "social responsibility" of economic entities. The results of the study are the establishment of the essence and interaction of terms that preceded the category of "social responsibility" of economic entities: according to the directions of social risks, the results of their influence and the emergence of social consequences or even social alienation due to poverty, deprivation, discrimination, marginalization and lumenization. Formation of social protection measures and its security. Conclusions. The study made it possible to understand the importance of social responsibility of economic entities and to determine the role in the formation of a socially oriented economy in Ukraine in the postwar period.

Оценка надежности асинхронных дизель-генераторных установок переменной частоты вращения

Calculation and subsequent analysis of reliability indicators is a mandatory stage of development and commissioning of technical devices. There has been carried out an assessment of reliability in relation to diesel generator sets operating in the mode of adjustable rotational speed at shared loads, which ensures their high energy efficiency. Unconditional compliance with the requirements for the quality of the generated energy (amplitude and frequency of the voltage in the ship's network) is realized in these generating devices by means of semiconductor converter technology. It is obvious that the increased technical complexity of variable-speed generator sets, which can be attributed to the class of machine-valve generator complexes, is associated with a certain decrease in their reliability indicators. There are presented structural schemes and indicated the composition of power equipment and controls for machine-valve generator complexes based on asynchronous generators with a short-circuited and phase rotor. The method of calculating the reliability indicators of these asynchronous diesel generator complexes is considered. The results of calculating the failure rate and operating time for failure are given, taking into account the load diagram of the power plant and the tachogram of the drive internal combustion engine, which corresponds to operation at energy-efficient rotational speeds at optimal (close to nominal) specific fuel consumption. The results of a comparative analysis of the operating time for failure allow us to determine the most reliable version of asynchronous generator electrical installation in operation.

Developed woven structures for denim materials

Denim is a cotton or cotton-blend twill textile material that is very popular to use for manufacturing different fashionable clothing items, such as jeans, jackets, skirts, shirts, and caps, and it is worn by most people across all age groups. Unfortunately, this material causes damage to the environment and human health through the large quantities of water required to grow the cotton plant, the toxic substances needed to dye the textile, the process of sandblasting to give denim an old, worn look and the large amounts of waste that result from its vast usage. This research aimed to develop advanced denim materials based on a blend of high-tech fibres, eco-friendly fibres with silver ions (Ag) and cotton fibres. The main purposes of developing these materials were to improve the mechanical potential under the repeated stresses of traction, friction, and tearing and to improve the psychosensory comfort by optimally combining the fabric pattern, the fibrous composition and the component yarn structure. By prolonging the life of these materials so that people can wear them longer, denim textile manufacturers can contribute to the global effort to become more sustainable. The textile structures were designed using the logical design scheme of a woven structure. The preparation of yarns for weaving and the weaving process was performed on equipment from the Experimental Station of the National Research and Development Institute for Textiles and Leather (INCDTP). Finally, the physio- mechanical characteristics of the fabric were examined, and the performances were validated.

Концептуальная модель цифровой трансформации производственных предприятий

The challenges associated with the digital transformation of industrial enterprises are discussed. The effective-ness of enterprises in the face of rapid change will depend on the principles and approaches to the digitization of business processes. The aim of the present study is to justify the principles and model of digital transfor-mation of manufacturing enterprises to increase flexibility and adapt to market changes using digital technolo-gies. Digitalization of manufacturing should be considered as a system innovation, and its large-scale benefits can only be realized if all functional units of an enterprise share relevant digital data. The scientific novelty of this paper consists in proposing the author’s conceptual model of digital transformation of manufacturing en-terprises. The structural scheme of the digital dynamic enterprise management system containing three func-tional blocks: operational, analytical and change management block is presented. The results obtained from the study may be beneficial to practitioners who plan and implement the digitalization of enterprises that use business models focused on the changing demands of consumers.

Assessment and Control of Construction Risk for a Super-Sized Quasi-Rectangular Pipe-Jacking Tunnel Adjacently to High-Speed Railways: A Case Study

Constructing super-sized quasi-rectangular pipe-jacking tunnels beneath high-speed railways presents a significant risk to both the railways and the tunnels. This paper uses expert inquiry, numerical simulation, fuzzy comprehensive evaluation, and on-site monitoring to assess and control risks for constructing a super-sized quasi-rectangular pipe-jacking tunnel project beneath high-speed railways. An assessment system including 18 factors from 6 aspects is built by integrating existing literature, expert consultation, and causality analysis. As the insufficient number of projects, the Analytic Hierarchy Process (AHP), Fuzzy Comprehensive Evaluation Method (FCEM), Delphi method, and numerical simulation are employed to establish a risk assessment model. The pre-support roof construction (P-SRC) technology is proposed to control tunnel construction risks. The actual scenario on site examines the validity and practicality of the evaluation model and control measures. The results indicate that the super-sized quasi-rectangular pipe-jacking tunnel sections for planned and operational high-speed railways belong to the level I risk, requiring risk reduction measures. The artificial borehole piles + D-shaped beams scheme and pile-plate structure scheme decrease the construction risk from level I to IV, and the evaluated risk results and control effect are in good agreement with actual construction conditions. The proposed risk assessment method and control technology are reasonable and reliable, providing a scientific reference for similar projects.

Real-Time, Non-Invasive Magnetic Field Imaging for Diagnosing Current Flow Patterns inside Fault-Simulated Li-Ion Batteries

With the growing popularity of Li-ion batteries in electric-powered mobility, securing battery safety has become a common goal of the battery community. Battery failures are commonly caused by small, undetectable defects that can form during manufacturing and operation, ranging from materials to the cell level. Although the small errors inside the cells trigger catastrophic failures, tracing them and distinguishing cell failure modes without cell anatomy remains challenging. Given that several defects within the cell could cause abnormal current flow compared to the normal cells, visualization of the current inside the battery is informative to find and trace the invisible defects that cannot be detected using imaging tools for the internal structure of fully packaged commercial cells.This study presents a real-time, non-invasive magnetic field imaging (MFI) method that can signal the magnetic field induced by battery current flow inside the Li-ion pouch cell during cycling (Figure 1). MFI can offer high-speed scanning in a few minutes (~100 mm/min) and spatially high resolution (0.161 mm2) and immediately measure the magnetic field with no need for shielding commonly required for MRI measurement. Based on the Biot-Savart law, we validated magnetic field-current correlation through the MFI of current-carrying 1D straight wires and 2D planes. Then, we found the optimal pouch cell structure for visualizing the current flow patterns using MFI and successfully converted the MFI contour map of the pouch cells into the normalized current distribution. To demonstrate the efficacy of current pattern analysis, we have collected MFI results of fault-simulated batteries (FSBs) to distinguish failure modes that intentionally possess cell manufacturing faults, such as lead-tab contact failure, electrode alignment, and stacking faults. Magnetic field offset using countercurrent-carrying, pouch cell-shaped 2D conductor underneath can selectively detect the failure spots where the current abnormally flows. It is believed that direct visualization of current distribution patterns and figuring out the pattern changes during operation can expedite the non-destructive, immediate diagnosis of commercial cells and troubleshoot safety-related challenges. Figure 1. Single-layer pouch cells and in operando MFI analysis during charging. (a) Scheme for internal structure of single-layer pouch cell (60 × 90 mm2) with counter-side, center-aligned tabs (CS-C cell). (b) Actual image of CS-C cell and MFI scan and applied current directions during the cell charging. MFI mapping images for (c) Bx , (d) By and (e) Bz vector fields at the cell. White arrows within each MFI contour map indicate the current flow prediction. Applying current density: 5.09 mA cm−2, the cell was situated 6 mm below the sensor (z-distance: 2.5 mm, scanned side: Cathode-side up). The total number of scanned data points are 1699 (11 cm) and 64 (16 cm) in y- and x-directions, respectively. Figure 1