Publications

SA-RL Algorithm Based Ship Steering Controller

Based on simulated annealing (SA) and reinforcement learning (RL) algorithm, a hybrid intelligent controller is proposed to ship steering. The SA algorithm is a powerful way to solve hard combinatorial optimization problems, which is used to adjust the parameters of the controller in this paper. The RL algorithm shows its particular superiority in ship steering, which just needs simple fuzzy information. With the advantages of the two algorithms, the controller can overcome the influence of the wind, wave and flow, the limitation that data are not exactly accurate. At last, the results of the simulation show that the ship course can be properly controlled when changeable wind, wave, and measure error exists.

Microstructural aspects of cement hydration - ultrasonic waves and numerical simulation

In this paper, an ultrasonic shear wave reflection method was adopted to mimic the microstructural evolution of hydrating Portland cement pastes with different water/cement-ratios (0.35, 0.5 and 0.6) cured under a constant temperature of 25°C. The reflection coefficient measured with this technique was correlated to microstructural parameters of the cement pastes. The appli- cation of numerical simulation has shown that the ultrasonic wave reflection technique can be used to efficiently monitor the microstructural evolution of cementitious materials.

A review on self-healing in reinforced concrete structures in view of serving conditions.

In this paper, different mechanisms of self-healing, i.e. self-healing based on adhesive agents, self-healing based on bacteria, self-healing based on autogenous self-healing were described. Their required conditions were summarized. The previous investigations showed that all mechanisms of self-healing are effective to some extend under particular conditions. In this paper, concrete structures were categorized according to serving conditions. Potential self-healing mechanisms are pointed out according to the required conditions of each self-healing mechanism.

Preparation of Sulphoaluminate Cement-Based Material from Municipal Solid Waste Incineration (MSWI) Fly Ash

This letter presents a feasible method for the preparation of Sulphoaluminate cement-based material (SCBM) from a hazardous industrial waste, i.e., MSWI fly ash. The produced materials were characterized by X-ray powder (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS) and mercury intrusion porosimeter (MIP). Experimental results show that a type of SCBM was successfully prepared from MSWI fly ash by controlling compositional parameters at right values, and firing the raw mixes at 1200°C for 2 h. Results also show that MSWI fly ash improves the burnability of raw mixes significantly, and for the investigated fly ash sample the maximum allowable content is 30 wt%. The morphology of C4A3S in the produced materials appears smaller in size, rounded in shape crystals and tends to form large agglomerates, in contrast to the slightly angular outline of beton-C2S grains. MIP test result indicates that the critical pore diameter decreases rapidly at early ages (< 1 day), and attains to a steady-state after 3 days of hydration.

Synergistic Effect of Potassium Iodide with L-Tryptophane on the Corrosion Inhibition of Mild Steel: A Combined Electrochemical and Theoretical Study

The inhibition effects of L-tryptophane (Trp) and its synergistic effect with KI on the corrosion of mild steel in 1.0 M HCl solution have been investigated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) measurements.The results show that the inhibition efficiency increases with the concentration of Trp and increases further when KI exists.The synergistic effect between Trp and KI was discussed by calculating the synergism parameter, which suggests that there is a cooperative mechanism between iodide anion and Trp cation.Finally, Monte Carlo simulation was utilized to search for the equilibrium configurations of inhibitors/Fe(110) adsorption systems in the presence of water molecules.

A dissolution model of alite coupling surface topography and ions transport under different hydrodynamics conditions at microscale

Portland cement is the most produced material in the world. The hydration process of cement consists of a group of complex chemical reactions. In order to investigate the mechanism of cement hydration, it is vital to study the hydration of each phase separately. An integrated model is proposed in this paper to simulate the dissolution of alite under different hydrodynamic conditions at microscale, coupling Kinetic Monte Carlo model (KMC), Lattice Boltzmann method (LBM) and diffusion boundary layer (DBL). The dissolution of alite is initialised with KMC. Two Multiple-relaxation-time (MRT) LB models are used to simulate the fluid flow and transport of ions, respectively. For solid-liquid interface, DBL is adapted to calculate the concentration gradient and dissolution flux. The model is validated with experiment from literature. The simulation results show good agreements with the results published in the literature.

Autogenous shrinkage induced stress of alkali activated slag and fly ash concrete under restraint condition

Modelling macroscopic shrinkage of hardened cement paste considering C-S-H densification

Shrinkage of hardened cement paste is a direct result of its desorption isotherm. The relationship between the desorption isotherm and the relative humidity in a hydrating cement paste is mainly controlled by the pore size distribution (nanopores to micropores). There are several hydration models to describe the microstructure of cement paste, but the desorption isotherm and self-desiccation are not direct outputs from those models as they are usually given as constitutive inputs. In this study an attempt was made to fill this gap by predicting the sorption isotherm, the drying shrinkage and the self-desiccation of cement paste directly from the evolution of its microstructure. A simple hydration model was developed to predict the microstructure of Portland cement pastes, as well as the nanostructure of calcium silicate hydrate (C-S-H), considering its densification during cement hydration. Predictions from the model were compared with some recent experimental findings from studies in the literature where the influence of the water-to-cement ratio was evaluated. The main contribution of this work is the integration of nanoscale and microscale material models towards determining the macroscopic properties of cement paste.

Ponašanje betona pri kombiniranom djelovanju okoliša i mogućnosti primjene na alkalno-aktivirane materijale

Alkali Activated Materials (AAMs), which are locally available alumino-silicate based materials, are emerging as alternative binders to Ordinary Portland Cement (OPC) due to higher performance and reduced carbon footprint.Before their implementation on a larger scale, their durability performance needs to be fully understood.The data on durability performance of AAMs under single environmental action are limited, and there are almost no data on their behaviour under two or more environmental actions.This article provides brief literature review on novel methods for determining durability of concrete under combined environmental actions, which could be utilised to determine the behaviour of AAMs under combined environmental actions.

Improved fiber distribution and mechanical properties of engineered cementitious composites by adjusting the mixing sequence

Modelling of time dependency of chloride diffusion coefficient in cement paste

Gemini Molecular Assembly Colocalization (GOAL): Accurate and Efficient Fusion Genotyping for Chronic Myeloid Leukemia Intelligent Diagnosis

Abstract RNA small fragment aberrances are associated with diseases by mediating a range of pathogenesis and pathological processes. DNA assembly‐based barcoding and amplification technologies are currently being actively explored for RNA in situ analysis. However, these modular integrated DNA assembly processes are inevitably accompanied with false positive signals caused by unexpected misassembly. Completely avoiding this phenomenon through simple and universal methods is challenging. Here, a novel dual‐input to dual‐output in situ analysis paradigm is proposed, aiming to improve target specificity through co‐recognition (dual‐input) and to eliminate false positive misassembly through fluorescent signal co‐localization (dual‐output). Based on this paradigm, Gemini molecular assembly co‐localization (GOAL) in situ imaging system is launched to accurately distinguish the fusion gene subtypes associated with chronic myeloid leukemia (CML), and to precisely report the proportion of minimum residual cancer cells in clinical samples by intelligent co‐localization counting and sorting. GOAL achieves highly sensitive and accurate genotyping recognition of 0.01% CML tumor cells and realizes fully automatic rapid diagnosis with a customized Intelligent Cell Image Sorter (iCis). iCis‐assisted GOAL represents an innovative and versatile molecular toolkit for accurate, rapid, user‐friendly, and professional‐independent profiling of cancer cells with RNA small fragment aberrances, providing efficient clinical decision support for disease diagnosis.

Influence of moisture condition on chloride diffusion in partially saturated ordinary Portland cement mortar

Experiments have been carried out to study the influence of moisture condition, including moisture content and its distribution, on the chloride diffusion in partially saturated ordinary Portland cement mortar. The mortar samples with water-to-cement (w/c) ratios of 0.4, 0.5 and 0.6, cured for 1 year, were preconditioned to uniform water saturations ranging from 18 to 100%. The interior relative humidities of these partially saturated cement mortars, i.e. water vapour desorption isotherm (WVDI), were measured. The WVDI results in relation to the pore structures obtained from the mercury intrusion porosimetry tests of paste samples with the same w/c ratios were analyzed, which provided a basic insight into the moisture distribution in the non-saturated cement mortars. The relative chloride diffusion coefficients of cement mortars at various water saturations were determined based on the Nernst-Einstein equation and conductivity technique. It is found that the relative chloride diffusion coefficient Drc depends on the degree of water saturation Sw and WVDI. At a given Sw level, the Drc is larger for a higher w/c ratio. The role of the w/c ratio in the Drc–Sw relation, however, becomes less pronounced with increasing w/c ratio. There exists a critical saturation, below which the water-filled capillary pores are discontinuous and the Drc-value tends towards infinitely small. An increase of the w/c ratio results in a decrease of the critical saturation level.

Effects of Municipal Solid Waste Incineration (Mswi) Bottom Ash Incorporation on the Microstructure and Performance of Blended Cementitious Materials: A Critical Review

Role of Curing Conditions and Precursor on the Microstructure and Phase Chemistry of Alkali-Activated Fly Ash and Slag Pastes

Understanding the role of curing conditions on the microstructure and phase chemistry of alkali-activated materials (AAMs) is essential for the evaluation of the long-term performance as well as the optimization of the processing methods for achieving more durable AAMs-based concretes. However, this information cannot be obtained with the common material characterization techniques as they often deliver limited information on the chemical domains and proportions of reaction products. This paper presents the use of PhAse Recognition and Characterization (PARC) software to overcome this obstacle for the first time. A single precursor (ground granulated blast-furnace slag (GBFS)) and a binary precursor (50% GBFS–50% fly ash) alkali-activated paste are investigated. The pastes are prepared and then cured in sealed and unsealed conditions for up to one year. The development of the microstructure and phase chemistry are investigated with PARC, and the obtained results are compared with independent bulk analytical techniques X-ray Powder Fluorescence and X-ray Powder Diffraction. PARC allowed the determination of the type of reaction products and GBFS and FA’s spatial distribution and degree of reaction at different curing ages and conditions. The results showed that the pastes react at different rates with the dominant reaction products of Mg-rich gel around GBFS particles, i.e., Ca-Mg-Na-Al-Si, and with Ca-Na-Al-Si gel, in the bulk paste. The microstructure evolution was significantly affected in the unsealed curing conditions due to the Na+ loss. The effect of the curing conditions was more pronounced in the binary system.

Numerical Studies of the Effects of Water Capsules on Self-Healing Efficiency and Mechanical Properties in Cementitious Materials

In this research, self-healing due to further hydration of unhydrated cement particles is taken as an example for investigating the effects of capsules on the self-healing efficiency and mechanical properties of cementitious materials. The efficiency of supply of water by using capsules as a function of capsule dosages and sizes was determined numerically. By knowing the amount of water supplied via capsules, the efficiency of self-healing due to further hydration of unhydrated cement was quantified. In addition, the impact of capsules on mechanical properties was investigated numerically. The amount of released water increases with the dosage of capsules at different slops as the size of capsules varies. Concerning the best efficiency of self-healing, the optimizing size of capsules is 6.5 mm for capsule dosages of 3%, 5%, and 7%, respectively. Both elastic modulus and tensile strength of cementitious materials decrease with the increase of capsule. The decreasing tendency of tensile strength is larger than that of elastic modulus. However, it was found that the increase of positive effect (the capacity of inducing self-healing) of capsules is larger than that of negative effects (decreasing mechanical properties) when the dosage of capsules increases.

Porosity characterization of ITZ in cementitious composites: Concentric expansion and overflow criterion

Effect of the Sodium Silicate Modulus and Slag Content on Fresh and Hardened Properties of Alkali-Activated Fly Ash/Slag

This paper presents the results of an experimental study performed to investigate the effect of activator modulus (SiO2/Na2O) and slag addition on the fresh and hardened properties of alkali-activated fly ash/slag (AAFS) pastes. Four activator moduli (SiO2/Na2O), i.e., 0.0, 1.0, 1.5, and 2.0, and five slag-to-binder ratios, i.e., 0, 0.3, 0.5, 0.7, 1.0, were used to prepare AAFS mixtures. The setting time, flowability, heat evolution, compressive strength, microstructure, and reaction products of AAFS pastes were studied. The results showed that the activator modulus and slag content had a combined effect on the setting behavior and workability of AAFS mixtures. Both the activator modulus and slag content affected the types of reaction products formed in AAFS. The coexistence of N–A–S–H gel and C–A–S–H gel was identified in AAFS activated with high pH but low SiO2 content (low modulus). C–A–S–H gel had a higher space-filling ability than N–A–S–H gel. Thus, AAFS with higher slag content had a finer pore structure and higher heat release (degree of reaction), corresponding to a higher compressive strength. The dissolution of slag was more pronounced when NaOH (modulus of 0.0) was applied as the activator. The use of Na2SiO3 as activator significantly refined the pores in AAFS by incorporating soluble Si in the activator, while further increasing the modulus from 1.5 to 2.0 prohibited the reaction process of AAFS, resulting in a lower heat release, coarser pore structure, and reduced compressive strength. Therefore, in view of the strength and microstructure, the optimum modulus is 1.5.