Evaluation of concrete compressive strength based on an improved PSO-LSSVM model

Xinhua Xue 사단법인 한국계산역학회 2018 Computers and Concrete, An International Journal Vol.21 No.5

This paper investigates the potential of a hybrid model which combines the least squares support vector machine (LSSVM) and an improved particle swarm optimization (IMPSO) techniques for prediction of concrete compressive strength. A modified PSO algorithm is employed in determining the optimal values of LSSVM parameters to improve the forecasting accuracy. Experimental data on concrete compressive strength in the literature were used to validate and evaluate the performance of the proposed IMPSO-LSSVM model. Further, predictions from five models (the IMPSO-LSSVM, PSOLSSVM, genetic algorithm (GA) based LSSVM, back propagation (BP) neural network, and a statistical model) were compared with the experimental data. The results show that the proposed IMPSO-LSSVM model is a feasible and efficient tool for predicting the concrete compressive strength with high accuracy.

Earthquake safety assessment of an arch dam using an anisotropic damage model for mass concrete

Xinhua Xue,Xingguo Yang 사단법인 한국계산역학회 2014 Computers and Concrete, An International Journal Vol.13 No.5

The seismic safety of concrete dams is one of the important problems in the engineering due to the vast socio-economic disasters which may be caused by collapse of these infrastructures. The accuracy of the risk evaluation associated with these existing dams as well as the efficient design of future dams is highly dependent on a proper understanding of their behaviour due to earthquakes. This paper develops an anisotropic damage model for arch dam under strong earthquakes. The modified Drucker-Prager criterion is adopted as the failure criteria of the dynamic damage evolution of concrete. Some process fields and other necessary information for the safety evaluation are obtained. The numerical results show that the seismic behaviour of concrete dams can be satisfactorily predicted.

Damage analysis of arch dam under blast loading

Xinhua Xue,Xingguo Yang,Wohua Zhang 사단법인 한국계산역학회 2013 Computers and Concrete, An International Journal Vol.12 No.1

This paper examines the dynamic response of an arch dam subjected to blast loading. A damage model is developed for three dimensional analysis of arch dams. The modified Drucker-Prager criterion is adopted as the failure criteria of the damage evolution in concrete. Then, Xiluodu arch dam serves as an example to simulate the failure behaviors of structures with the proposed model. The results obtained using the proposed model can reveal the reliability degree of the safe operation level of the high arch dam system as well as the degree of potential failure, providing a reliable basis for risk assessment and risk control

Neuro-fuzzy based approach for estimation of concrete compressive strength

Xinhua Xue,Hongwei Zhou 사단법인 한국계산역학회 2018 Computers and Concrete, An International Journal Vol.21 No.6

Compressive strength is one of the most important engineering properties of concrete, and testing of the compressive strength of concrete specimens is often costly and time consuming. In order to provide the time for concrete form removal, re-shoring to slab, project scheduling and quality control, it is necessary to predict the concrete strength based upon the early strength data. However, concrete compressive strength is affected by many factors, such as quality of raw materials, water cement ratio, ratio of fine aggregate to coarse aggregate, age of concrete, compaction of concrete, temperature, relative humidity and curing of concrete. The concrete compressive strength is a quite nonlinear function that changes depend on the materials used in the concrete and the time. This paper presents an adaptive neuro-fuzzy inference system (ANFIS) for the prediction of concrete compressive strength. The training of fuzzy system was performed by a hybrid method of gradient descent method and least squares algorithm, and the subtractive clustering algorithm (SCA) was utilized for optimizing the number of fuzzy rules. Experimental data on concrete compressive strength in the literature were used to validate and evaluate the performance of the proposed ANFIS model. Further, predictions from three models (the back propagation neural network model, the statistics model, and the ANFIS model) were compared with the experimental data. The results show that the proposed ANFIS model is a feasible, efficient, and accurate tool for predicting the concrete compressive strength.

Study on relations between porosity and damage in fractured rock mass

Xue, Xinhua Techno-Press 2015 Geomechanics & engineering Vol.9 No.1

The porosity is often regarded as a linear function of fluid pressure in porous media and permeability is approximately looked as constants. However, for some scenarios such as unconsolidated sand beds, abnormal high pressured oil formation or large deformation of porous media for pore pressure dropped greatly, the change in porosity is not a linear function of fluid pressure in porous media, and permeability can't keep a constant yet. This paper mainly deals with the relationship between the damage variable and permeability properties of a deforming media, which can be considered as an exploratory attempt in this field.

Theoretical formulation of double scalar damage variables

Xinhua Xue,Wohua Zhang 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.19 No.5

The predictive utility of a damage model depends heavily on its particular choice of a damage variable, which serves as a macroscopic approximation in describing the underlying micromechanical processes of microdefects. In the case of spatially perfectly randomly distributed microcracks or microvoids in all directions, isotropic damage model is an appropriate choice, and scalar damage variables were widely used for isotropic or one-dimensional phenomenological damage models. The simplicity of a scalar damage representation is indeed very attractive. However, a scalar damage model is of somewhat limited use in practice. In order to entirely characterize the isotropic damage behaviors of damaged materials in multidimensional space, a system theory of isotropic double scalar damage variables, including the expressions of specific damage energy release rate, the coupled constitutive equations corresponding to damage, the conditions of admissibility for two scalar damage effective tensors within the framework of the thermodynamics of irreversible processes, was provided and analyzed in this study. Compared with the former studies, the theoretical formulations of double scalar damage variables in this study are given in the form of matrix, which has many features such as simpleness, directness, convenience and programmable characteristics. It is worth mentioning that the above-mentioned theoretical formulations are only logically reasonable. Owing to the limitations of time, conditions, funds, etc. they should be subject to multifaceted experiments before their innovative significance can be fully verified. The current level of research can be regarded as an exploratory attempt in this field.

Real Scene Text Image Super-Resolution Based on Multi-Scale and Attention Fusion

Xinhua Lu,Haihai Wei,Li Ma,Qingji Xue,Yonghui Fu 한국정보처리학회 2023 Journal of information processing systems Vol.19 No.4

Plenty of works have indicated that single image super-resolution (SISR) models relying on synthetic datasetsare difficult to be applied to real scene text image super-resolution (STISR) for its more complex degradation. The up-to-date dataset for realistic STISR is called TextZoom, while the current methods trained on this datasethave not considered the effect of multi-scale features of text images. In this paper, a multi-scale and attentionfusion model for realistic STISR is proposed. The multi-scale learning mechanism is introduced to acquiresophisticated feature representations of text images; The spatial and channel attentions are introduced to capturethe local information and inter-channel interaction information of text images; At last, this paper designs amulti-scale residual attention module by skillfully fusing multi-scale learning and attention mechanisms. Theexperiments on TextZoom demonstrate that the model proposed increases scene text recognition’s (ASTER)average recognition accuracy by 1.2% compared to text super-resolution network.

Hybrid PWM Modulation Technology Applied to Three-Level Topology-Based PMSMs

Yuanxi Chen,Xinhua Guo,Jiangyu Xue,Yifeng Chen 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.1

The inverter is an essential part of permanent magnet synchronous motor (PMSM) drive systems. The performance of aninverter is greatly influenced by its modulation strategy. Using a proper management of modulation strategies can guarantee highperformance from a PMSM under various speed conditions. Switching between modulations is a pivotal technique thatdetermines the performance of a PMSM. Most works on hybrid methods focus on two-level induction motors drive systems. Inthis paper, in order to improve the performance of PMSMs under various speed conditions, a hybrid method of a pulse widthmodulation (PWM) control scheme based on a neutral-point-clamped (NPC) three level topology was proposed. This hybridPWM modulation comprised space vector PWM (SVPWM) and selective harmonic elimination PWM (SHEPWM). Under lowspeed conditions, the SVPWM is employed to cause the PMSM to start smoothly, and to obtain a rapid response from the controlsystem. Under high speed conditions, the SHEPWM is employed to reduce the switching frequency and to eliminate particularcurrent harmonics. Moreover, the harmonic characteristics of different modulations are analyzed to obtain a smooth transitionbetween the SHEPWM and the SVPWM. Experimental and simulation results indicated the effectiveness of the proposed controlmethod.

Hybrid PWM Modulation Technology Applied to Three-Level Topology-Based PMSMs

Chen, Yuanxi,Guo, Xinhua,Xue, Jiangyu,Chen, Yifeng The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.1

The inverter is an essential part of permanent magnet synchronous motor (PMSM) drive systems. The performance of an inverter is greatly influenced by its modulation strategy. Using a proper management of modulation strategies can guarantee high performance from a PMSM under various speed conditions. Switching between modulations is a pivotal technique that determines the performance of a PMSM. Most works on hybrid methods focus on two-level induction motors drive systems. In this paper, in order to improve the performance of PMSMs under various speed conditions, a hybrid method of a pulse width modulation (PWM) control scheme based on a neutral-point-clamped (NPC) three level topology was proposed. This hybrid PWM modulation comprised space vector PWM (SVPWM) and selective harmonic elimination PWM (SHEPWM). Under low speed conditions, the SVPWM is employed to cause the PMSM to start smoothly, and to obtain a rapid response from the control system. Under high speed conditions, the SHEPWM is employed to reduce the switching frequency and to eliminate particular current harmonics. Moreover, the harmonic characteristics of different modulations are analyzed to obtain a smooth transition between the SHEPWM and the SVPWM. Experimental and simulation results indicated the effectiveness of the proposed control method.