Recursive Analysis Method Research Articles

Analysis of P-wave propagation in filled jointed rock mass with viscoelastic properties

Stress wave propagation in filled jointed rock mass is an important basis for the analysis of rock dynamic stability. The presence of small cracks in rock mass often causes the rock to exhibit viscoelastic behavior, resulting in the amplitude attenuation and time delay of the stress wave. In view of the incomplete understanding of stress wave propagation in viscoelastic media, this study presents an analysis on stress wave propagation in filled jointed rock mass with viscoelastic properties based on the time-domain recursive analysis method. By introducing the quality factors of stress wave in viscoelastic medium, the propagation equation of plane P-wave in filled jointed rock mass with viscoelasticity is established. Subsequently, the transmission and reflection characteristics of P-wave are accordingly analyzed. The results indicate that the transmission and reflection coefficients of P-wave through the filled joint decrease obviously due to the attenuation effect of rock viscoelasticity on wave amplitude, but the coefficients gradually stabilize as the quality factor increases. As the propagation distance of the P-wave increases in viscoelastic rock masses, the transmission and reflection coefficients decrease gradually. The normal stiffness of joint contact interface has a decisive influence on the wave propagation. Specifically, a higher normal stiffness leads to stronger transmission and poorer reflection. The larger the thickness of filled joint, the more obvious the attenuation of P-wave becomes. Additionally, the viscoelasticity of filling layer further aggravates the influence of joint thickness on the attenuation of P-wave. The study comprehensively takes into account the effect of viscoelasticity of both the rock mass and the filling layer on transmission and reflection of waves. The research results provide certain theoretical support for the dynamic response and stability analysis of rock mass containing structural planes.

RECURRENT ANALYSIS OF ENERGY CONSUMPTION OF A METALLURGICAL ENTERPRISE

The subject of the study is the study of models and methods for short-term forecasting of energy consumption in power systems based on recurrent analysis of time series. The aim of the work is a recurrent analysis of the time series of energy consumption of a metallurgical enterprise and the development of a program in the Matlab environment for automating calculations and experimental testing of data available for research in PJSC Electrometallurgical Plant "Dniprospetsstal" named after A. M. Kuzmin. The following tasks have been solved: the methodology for constructing recurrent diagrams and their quantitative analysis have been considered; a model of the time series and the phase trajectory of the time series was built to visualize the change in energy consumption during the day; software for constructing recurrent diagrams in the Matlab package was developed. Methods were used: analysis of time series based on recursive analysis to study the characteristics of the state of the system on the example of a metallurgical enterprise. The results were obtained: software was developed in the Matlab environment for short-term forecasting of energy consumption in power systems, and quantitative indicators were calculated that can be used to characterize the state of the system and analyze energy consumption in the summer and winter seasons. Conclusions: in the course of the study, software for constructing and quantitative analysis of recurrence diagrams in the Matlab package was developed, with the help of which patterns were discovered and information about the properties of the system under study was obtained. Based on the analysis of the average values of quantitative measures in the off-season for 2018–2021, it can be seen that the summer period is characterized by greater predictability, as well as a significantly higher latency indicator, which characterizes the average time when the system can spend in a more or less unchanged state. Confirmed on real data, the benefits of using the recursive analysis method for estimating electricity consumption, as well as more efficient modeling of this process, can lead to an increase in the accuracy of forecasting its future dynamics.

Distributed dual objective control of an energy storage system under jointly connected switching networks

This paper studies a dual objective control problem for an energy storage system (ESS) consisting of multiple independently-controlled energy storage units (ESUs). The power output of the entire ESS is designed to meet its reference, and meanwhile the state-of-energy (SOE) of all the ESUs maintains to be balanced. In practice, the communication among ESUs might be unreliable and thus is modeled by jointly connected switching networks. By making use of the so-called Generalized Krasovskii–LaSalle Theorem together with a novel two-step recursive analysis method, it is rigorously proven that the dual objective control problem subject to jointly connected switching networks can be solved by a consensus-based distributed control algorithm.

Experimental Evaluation of Wearable Piezo Ring for Bolted Connection Monitoring Using the Active Sensing Approach

As a safe and reliable connection, bolted connection is widely used in various structural systems. Monitoring the bolted connection is beneficial to ensure the safety of the whole structure. In this study, a wearable piezoelectric ring based on piezoelectric material is designed and it can be easily integrated into the bolt connection as a washer. To verify the feasibility of wearable piezoelectric ring, single-bolt looseness experiment based on wearable piezoelectric ring was carried out. Firstly, the wearable piezoelectric ring was installed on the bolted joint, acting as a piezoelectric sensor, and multiple piezoelectric actuators were installed in different location of the plate surface. Then, different torque level was applied to the bolt and the stress wave signals were obtained by piezoelectric active sensing technique. Finally, the recursive analysis method was introduced to extract nonlinear recursive features of the stress wave signals. The experimental results showed that the change of the bolt looseness could be qualitatively characterized by the phase space trajectory and the recurrence plots. Moreover, the recursive entropy could quantitatively characterize the bolt looseness, showing a bright prospect in monitoring the bolt looseness using the wearable piezoelectric ring.

Module Partition Method of Embedded Multitasking Software Based on Fuzzy Set Theory

In order to improve the reliability of embedded multitask software, a module partition method based on fuzzy set theory is proposed to solve the problem of large number of software failures and high frequency of failures. Firstly, the characteristics of embedded multitask software are analyzed, and the constraint parameter distribution model is constructed. Then the reliability parameter analysis model of embedded multitask software is constructed, and the multilevel fuzzy metric structure combined with quantitative recursive analysis method is used to complete the division of embedded multitask software modules. The simulation results show that the accuracy of the proposed method exceeds 99% after the number of iterations exceeds 50. The experimental results show that the method has high reliability, high precision and high practicability.

A Diagnosis Method of Implementation State Management in Large-Scale Construction Projects

In the diagnosis researches on the implementation status of construction engineering projects (CEP), two major problems remain unsolved yet by far. On one hand, there is not a scientific approach to extract and determine the diagnosis indicators for the implementation status. On the other hand, it still lacks an effective method to analyze and diagnose the implementation status. As an improvement, in this paper these two problems are studied respectively. According to the three required conditions for the implementation status diagnosis, the determination approach based on quantitative scoring for the index setup is firstly presented. All of the indicators are transformed and standardized into the range value forms within [0,1]. Then, the recursive analysis method and model of the diagnosis indicators, which combines the model-based method together with the characteristic based method at the meantime, is proposed, and the grading judgment standards for the implementation status of CEP are presented based on the windage principle. Finally, an indemnificatory housing project which contains 21 residential buildings is taken for a case study to validate the proposed method. It is shown that the proposed method is able to effectively obtain the actual implementation status of large-scale construction projects and find out the exact problems as well as the targeted measures.

Higher-order beam bending theory for static, free vibration, and buckling analysis of thin-walled rectangular hollow section beams

In higher-order beam theories, cross-sectional deformations causing complex responses of thin-walled beams are considered as additional degrees of freedom. To fully capture their bending responses, enriched sectional modes departing from Vlasov’s assumptions have been utilized in recent studies. However, due to these bending-related modes, no available higher-order beam bending theory has established explicit stress-generalized force relations that are fully consistent with those by the classical beam theories and earlier studies based on Vlasov’s assumptions. If they are available, physical significance of the bending-related generalized forces can be readily understood. In addition, equilibrium conditions at a joint of multiple thin-walled beams can be explicitly derived. Here, we newly propose a higher-order beam bending theory that not only includes as many bending-related sectional modes as desired, but also provides the desired explicit stress-generalized force relations. To this end, we establish a recursive analysis method that derives hierarchical bending-related sectional modes. We show that this method can yield certain relations among the sectional mode shapes, which are critical in establishing the desired explicit relations. The validity of the present theory is confirmed by calculating the static, free vibration, and buckling responses of several thin-walled rectangular hollow section beams.

Research on propagation law of one-dimensional stress wave in jointed rock mass under in-situ stress

The propagation law of stress wave in jointed rock mass under in-situ stress has important engineering significance on blasting excavation and protection engineering design of deep rock mass. Based on theoretical analysis, the propagation law of stress wave across multiple nonlinear deformation joints under the initial stress is studied. Firstly, the propagation equation of stress wave across multiple nonlinear joints considering the influence of initial stresses is established, through the discontinuous deformation method (DDM) and the recursive analysis method of stress wave in time domain. On this basis, parametric studies are conducted for the effects of stress wave propagation, such as initial stress, the amplitude of stress wave, the distance and the number of joints. The results show that the existence of initial stress will affect the propagation of stress wave, the geometric distribution of joints, such as spacing and number, can also cause the change of stress wave transmission coefficients, and the amplitude of incident wave varies can also lead to the change of stress wave propagation.

Identification of gas-liquid two-phase flow patterns in dust scrubber based on wavelet energy entropy and recurrence analysis characteristics

For a wet dust scrubber, dust collection efficiency is tightly connected with the gas-liquid two-phase flow pattern. Using the characteristic parameters selected by current flow pattern identification methods, regions of significant coincidence exist among different patterns, thereby leading to a decline in the identification efficiency. In this study, a new method for processing the wavelet decomposition signal of the dust collector pressure was proposed to obtain the characteristic parameters that distinguish the flow pattern. Firstly, detailed information regarding the different frequency bands of the pressure signal was extracted via wavelet analysis. Then, in combination with the information entropy theory, wavelet energy entropy (WEE) was proposed to evaluate the uniformity of energy distribution in different frequency bands. The results show that WEE is sensitive to the change in gas-liquid two-phase flow patterns, and the corresponding distinguishing efficiency of flow patterns is 92.5%. There was only a small amount of crossover between the shear liquid curtain and entrainment air bubble pattern. For this, using the recursive analysis method (RAM), the characteristic recurrence plots (RP) and recurrence quantification analysis (RQA) of the original pressure signals and the wavelet decomposition signal with different frequency bands were obtained. Results show that the RP characteristics can intuitively reflect the gas-liquid flow state of different flow patterns. Although RQA characteristics are not sensitive to the change in low-level gas/liquid resonance flow pattern in the dust scrubber, it exhibits strong distinction to the evolution of other flow patterns. It effectively compensates for the crossover at the flow pattern distinguish between the shear liquid curtain and entrainment of air bubble using the parameters of the wavelet energy entropy. It is the highlight of this article that the combination of WEE and recurrence characteristics can effectively address the problems of high coincidence of flow pattern features in the dust scrubber.

Consistent higher-order beam theory for thin-walled box beams using recursive analysis: Edge-bending deformation under doubly symmetric loads

Thin-walled box beams generally exhibit complex sectional deformations that are not significant in solid beams. Accordingly, a higher-order beam theory suitable for the analysis of thin-walled box beams should include degrees of freedom representing sectional deformations. In a recent study, a recursive analysis method to systematically derive sectional membrane deformations has been proposed to establish a consistent higher-order beam theory. In this study, another recursive analysis method is proposed that is suitable for the closed-form derivation of new sectional bending deformations representing the bending of edges (or walls) of the cross-section shown in a box beam under doubly symmetric loads. A consistent 1D higher-order beam theory appropriate to include these additional deformation modes as beam degrees of freedom is also established. The proposed theory provides explicit formulas that relate stresses to generalized forces including self-equilibrated forces such as bimoments. Furthermore, sectional modes are hierarchically derived so that the level of solution accuracy can be effectively and systematically controlled. Thus, the accuracy for static displacement/stress calculations and eigenfrequencies can be adjusted to be fully comparable with plate/shell results. When general doubly symmetric loads are applied to a box beam, the edge membrane modes derived in an earlier study can also be used as additional degrees of freedom besides the edge-bending modes derived in this study. The validity of the proposed beam approach is verified through the analyses of static displacements and stresses as well as eigenfrequencies for free vibration problems.

Improvement and simulation of cost risk assessment model for intelligent building engineering

In order to reduce engineering cost and improve engineering quality and to realise risk cost forecast for intelligent building engineering cost. A novel risk assessment model for intelligent building engineering cost based on Markov model and adaptive equilibrium cooperative game is proposed. Firstly, constrained parameter model for building engineering cost risk assessment is constructed, and Markov model is adopted for engineering cost risk assessment objective function building. Secondly, the cost and quality of engineering cost are compared for balance cooperative game. Recursive analysis method is used for the adaptive optimisation of engineering cost's risk cost to achieve the associated fusion processing for engineering cost risk parameter value; Finally, fuzzy directive clustering method is used to achieve building engineering cost risk assessment and forecasting. Simulation results show that the method can be used to evaluate the cost of intelligent building, which improves the accurate forecasting ability of engineering cost and reduces the cost of engineering risk.

Study on high temperature collapse detection technology of reinforced concrete columns strengthened with angle steel

Reinforced concrete column strengthened with angle steel has strong high temperature resistance. Through the quantitative analysis and testing of the high temperature collapse of concrete column, the formula design of reinforced concrete column is improved to enhance the high temperature collapse performance of concrete column. Reinforced concrete columns high temperature collapse technology strengthened by angle steel based on bilinear elastic hysteretic model is proposed and equivalent linear recursive analysis method is used to calculate the restoring force model of concrete column. Experimental results show that the method can be used to calculate the ultimate crack depth and fracture toughness reliability of concrete column and detect high temperature collapse of reinforced concrete columns. It can be effectively combined with regular field nondestructive testing and long-term strain monitoring to achieve high temperature collapse of concrete column detection.

Cluster Consensus in Multiple Lagrangian Systems Under Pinning Control

This paper is mainly concerned with cluster tracking control for robotic networks whose dynamics are modeled by a Lagrangian equation with multiple leaders. An adaptive distributed pinning tracking control protocol is presented to realize cluster consensus, and the corresponding convergence analysis is given by utilizing the property of directed acyclic networks topology. Furthermore, by developing a recursive analysis method, a criterion that ensures the convergence for proposed algorithm is given. Subsequently, simulations conducted on the seven two-link revolute arms are presented to illustrate the effectiveness of the theoretical results.

Performance analysis and parameter setting for Tong detection algorithm

Tong detection algorithm is a common used signal detection algorithm. But the overall conclusions about statistical performance and parameter setting of Tong detection algorithm are absent. Aiming at these problems,statistical and recursive analysis methods were used to carry on theoretical analysis about mean value and variance of dwell times in signal search unit in detail,the corresponding expressions were given,a maximum dwell times constraint method was offered according to the 3Sigma principle. The relationships between detection probability,average dwell times of noise search unit and signal search unit,initial value and maximum value of algorithm counter,pre-detection signal to noise ratio were analyzed. Analysis results indicate that the parameters of Tong detection algorithm should be set according to signal strength and search modes,and the influence of parameter setting on detection probability and average dwell times of noise search unit or signal search unit should be balanced.

Bound of aspect ratio of base-isolated buildings considering nonlinear tensile behavior of rubber bearing

The purpose of this paper is to propose a simple analysis method of axial deformation of base-isolation rubber bearings in a building subjected to earthquake loading and present its applicability to the analysis of the bound of the aspect ratio of base-isolated buildings. The base shear coefficient is introduced as a key parameter for the bound analysis. The bound of the aspect ratio of base-isolated buildings is analyzed based on the relationship of the following four quantities; (i) ultimate state of the tensile stress of rubber bearings based on a proposed simple recursive analysis for seismic loading, (ii) ultimate state of drift of the base-isolation story for seismic loading, (iii) ultimate state of the axial compressive stress of rubber bearings under dead loads, (iv) prediction of the overturning moment at the base for seismic loading. In particular, a new recursive analysis method of axial deformation of rubber bearings is presented taking into account the nonlinear tensile behavior of rubber bearings and it is shown that the relaxation of the constraint on the ultimate state of the tensile stress of rubber bearings increases the limiting aspect ratio.