Experimental Study on Creep of Sandstone under Hydrochemical Corrosion

Abstract Corrosion creep of sandstone has great influence on the safety and stability of geotechnical engineering, and it is of great significance to study the creep characteristics of sandstone under the action of hydrochemical corrosion for the long-term stability of geotechnical engineering. Through creep test of corroded rock, the characteristics of rock deformation and strength are analyzed. Combined with electrochemical impedance spectroscopy (EIS), the microcracks of corroded sandstone during creep process are detected, and the variation law of equivalent circuit parameters and the development trend of microcracks during creep process of corroded sandstone are analyzed. The test results show that the creep characteristics of rock samples are related to the hydrochemical environment; The medium-and long-term strength of the solution with high pH value is relatively small, and the difference with uniaxial compressive strength is large; Moreover, there is a certain correlation between creep of rock samples and equivalent circuit parameters. In this paper, the influence of creep deformation, mechanical properties and hydrochemical environment on sandstone creep is analyzed, and the research results can provide reference for stability analysis of related geotechnical engineering.

Download Full-text

SUCCESSIVE LARGE PERTURBATION METHOD FOR THE EXTRACTION OF MORE ACCURATE EQUIVALENT-CIRCUIT-PARAMETERS IN SOLAR CELLS

Journal of Nonlinear Optical Physics & Materials ◽

10.1142/s0218863510005558 ◽

2010 ◽

Vol 19 (04) ◽

pp. 637-643 ◽

Cited By ~ 1

Author(s):

J. H. CAI ◽

N. SATOH ◽

M. YANAGIDA ◽

L. Y. HAN

Keyword(s):

Solar Cells ◽

Perturbation Method ◽

Equivalent Circuit ◽

Electrochemical Impedance ◽

Dye Sensitized Solar Cells ◽

Least Square ◽

Initial Value ◽

Dependence Problem ◽

Large Perturbation ◽

Equivalent Circuit Parameters

The numerical least-square fitting is a general method for the extraction of model parameter from experimental data. However, the method suffers from an initial value dependence problem when the method is used in I - V curve fitting. Recently we have proposed a successive large perturbation method (SLPM) to eliminate the initial value dependence problem. In this paper, we test the SLPM by comparing our results with previous published fitting results for various solar cells, such as traditional silicon solar cells and new type of organic solar cells and dye-sensitized solar cells. The method is available not only to the fitting for I - V curve, but also to the fitting for electrochemical impedance spectrum. Our test demonstrates that Newton-like method plus our SLPM is an accurate and robust method for the numerical extraction of equivalent circuit parameters in solar cells.

Download Full-text

Automatic Identification Algorithm of Equivalent Electrochemical Circuit Based on Electroscopic Impedance Data for a Lead Acid Battery

Electronics ◽

10.3390/electronics10111353 ◽

2021 ◽

Vol 10 (11) ◽

pp. 1353

Author(s):

Javier Olarte ◽

Jaione Martínez de Ilarduya ◽

Ekaitz Zulueta ◽

Raquel Ferret ◽

Unai Fernández-Gámiz ◽

...

Keyword(s):

Equivalent Circuit ◽

Electrochemical Impedance ◽

Differential Evolution Algorithm ◽

Automatic Identification ◽

Identification Algorithm ◽

Evaluation Procedures ◽

Impedance Data ◽

Simplex Search ◽

Equivalent Circuit Parameters ◽

Electrochemical Model

Obtaining tools to analyze and predict the performance of batteries is a non-trivial challenge because it involves non-destructive evaluation procedures. At the research level, the development of sensors to allow cell-level monitoring is an innovative path, and electrochemical impedance spectrometry (EIS) has been identified as one of the most promising tools, as is the generation of advanced multivariable models that integrate environmental and internal-battery information. In this article, we describe an algorithm that automatically identifies a battery-equivalent electrochemical model based on electroscopic impedance data. This algorithm allows in operando monitoring of variations in the equivalent circuit parameters that will be used to further estimate variations in the state of health (SoH) and state of charge (SoC) of the battery based on a correlation with experimental aging data corresponding to states of failure or degradation. In the current work, the authors propose a two-step parameter identification algorithm. The first consists of a rough differential evolution algorithm-based identification. The second is based on the Nelder–Mead Simplex search method, which gives a fine parameter estimation. These algorithm results were compared with those of the commercially available Z-view, an equivalent circuit tool estimation that requires expert human input.

Download Full-text

Fitting procedure based on Differential Evolution to evaluate impedance parameters of metal–coating systems

Engineering Computations ◽

10.1108/ec-11-2018-0513 ◽

2019 ◽

Vol 36 (9) ◽

pp. 2960-2982

Author(s):

Francisco González ◽

David Greiner ◽

Vicente Mena ◽

Ricardo M. Souto ◽

Juan J. Santana ◽

...

Keyword(s):

Differential Evolution ◽

Equivalent Circuit ◽

Electrochemical Impedance ◽

Accurate Solution ◽

Metal Coating ◽

Electrical Equivalent Circuit ◽

Content Type ◽

Fitting Procedure ◽

Equivalent Circuit Parameters ◽

Impedance Parameters

Purpose Impedance data obtained by electrochemical impedance spectroscopy (EIS) are fitted to a relevant electrical equivalent circuit to evaluate parameters directly related to the resistance and the durability of metal–coating systems. The purpose of this study is to present a novel and more efficient computational strategy for the modelling of EIS measurements using the Differential Evolution paradigm. Design/methodology/approach An alternative method to non-linear regression algorithms for the analysis of measured data in terms of equivalent circuit parameters is provided by evolutionary algorithms, particularly the Differential Evolution (DE) algorithms (standard DE and a representative of the self-adaptive DE paradigm were used). Findings The results obtained with DE algorithms were compared with those yielding from commercial fitting software, achieving a more accurate solution, and a better parameter identification, in all the cases treated. Further, an enhanced fitting power for the modelling of metal–coating systems was obtained. Originality/value The great potential of the developed tool has been demonstrated in the analysis of the evolution of EIS spectra due to progressive degradation of metal–coating systems. Open codes of the different differential algorithms used are included, and also, examples tackled in the document are open. It allows the complete use, or improvement, of the developed tool by researchers.

Download Full-text

Comparative Labelling and Biokinetic Studies of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn)

Nuklearmedizin ◽

10.1055/s-0037-1620603 ◽

1977 ◽

Vol 16 (01) ◽

pp. 30-35 ◽

Cited By ~ 1

Author(s):

N. Agha ◽

R. B. R. Persson

Keyword(s):

Complex Formation ◽

Significant Influence ◽

Room Temperature ◽

Ph Value ◽

Maximum Activity ◽

Reduction Step ◽

Labelling Yield ◽

Different Temperatures ◽

Kinetics Of

SummaryGelchromatography column scanning has been used to study the fractions of 99mTc-pertechnetate, 99mTcchelate and reduced hydrolyzed 99mTc in preparations of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn). The labelling yield of 99mTc-EDTA(Sn) chelate was as high as 90—95% when 100 μmol EDTA · H4 and 0.5 (Amol SnCl2 was incubated with 10 ml 99mTceluate for 30—60 min at room temperature. The study of the influence of the pH-value on the fraction of 99mTc-EDTA shows that pH 2.8—2.9 gave the best labelling yield. In a comparative study of the labelling kinetics of 99mTc-EDTA(Sn) and 99mTc- DTPA(Sn) at different temperatures (7, 22 and 37°C), no significant influence on the reduction step was found. The rate constant for complex formation, however, increased more rapidly with increased temperature for 99mTc-DTPA(Sn). At room temperature only a few minutes was required to achieve a high labelling yield with 99mTc-DTPA(Sn) whereas about 60 min was required for 99mTc-EDTA(Sn). Comparative biokinetic studies in rabbits showed that the maximum activity in kidneys is achieved after 12 min with 99mTc-EDTA(Sn) but already after 6 min with 99mTc-DTPA(Sn). The long-term disappearance of 99mTc-DTPA(Sn) from the kidneys is about five times faster than that for 99mTc-EDTA(Sn).

Download Full-text

Experimental and Analytical Study on Creep Characteristics of Box Section Bamboo-Steel Composite Columns under Long-Term Loading

Materials ◽

10.3390/ma14040983 ◽

2021 ◽

Vol 14 (4) ◽

pp. 983

Author(s):

Shixu Wu ◽

Keting Tong ◽

Jianmin Wang ◽

Yushun Li

Keyword(s):

Load Level ◽

Experimental Results ◽

Creep Model ◽

Composite Column ◽

Composite Columns ◽

Creep Coefficient ◽

Creep Characteristics ◽

Section Size ◽

Steel Composite

To expand the application of bamboo as a building material, a new type of box section composite column that combined bamboo and steel was considered in this paper. The creep characteristics of eight bamboo-steel composite columns with different parameters were tested to evaluate the effects of load level, section size and interface type under long-term loading. Then, the deformation development of the composite column under long-term loading was observed and analyzed. In addition, the creep-time relationship curve and the creep coefficient were created. Furthermore, the creep model of the composite column was proposed based on the relationship between the creep of the composite column and the creep of bamboo, and the calculated value of creep was compared with the experimental value. The experimental results showed that the creep development of the composite column was fast at first, and then became stable after about 90 days. The creep characteristics were mainly affected by long-term load level and section size. The creep coefficient was between 0.160 and 0.190. Moreover, the creep model proposed in this paper was applicable to predict the creep development of bamboo-steel composite columns. The calculation results were in good agreement with the experimental results.

Download Full-text

Mechanical Properties of Cement-Treated Soil Mixed with Cellulose Nanofibre

Applied Sciences ◽

10.3390/app11146425 ◽

2021 ◽

Vol 11 (14) ◽

pp. 6425

Author(s):

Hidenori Takahashi ◽

Shinya Omori ◽

Hideyuki Asada ◽

Hirofumi Fukawa ◽

Yusuke Gotoh ◽

...

Keyword(s):

Mechanical Properties ◽

Flexural Strength ◽

Geotechnical Engineering ◽

Strength Development ◽

Soft Ground ◽

Wood Cellulose ◽

Treated Soil ◽

Made In ◽

Cement Treatment

Cellulose nanofibre (CNF), a material composed of ultrafine fibres of wood cellulose fibrillated to nano-order level, is expected to be widely used because of its excellent properties. However, in the field of geotechnical engineering, almost no progress has been made in the development of techniques for using CNFs. The authors have focused on the use of CNF as an additive in cement treatment for soft ground, where cement is added to solidify the ground, because CNF can reduce the problems associated with cement-treated soil. This paper presents the results of a study on the method of mixing CNF, the strength and its variation obtained by adding CNF, and the change in permeability. CNF had the effect of mixing the cement evenly and reducing the variation in the strength of the treated soil. The CNF mixture increased the strength at the initial age but reduced the strength development in the long term. The addition of CNF also increased the flexural strength, although it hardly changed the permeability.

Download Full-text

Effects of Sugar Cane Molasses Addition on the Fermentation Quality, Microbial Community, and Tastes of Alfalfa Silage

Animals ◽

10.3390/ani11020355 ◽

2021 ◽

Vol 11 (2) ◽

pp. 355

Author(s):

Runbo Luo ◽

Yangdong Zhang ◽

Fengen Wang ◽

Kaizhen Liu ◽

Guoxin Huang ◽

...

Keyword(s):

Sugar Cane ◽

Ph Value ◽

Electronic Tongue ◽

Water Soluble ◽

Soluble Carbohydrates ◽

Cane Molasses ◽

Fermentation Quality ◽

Alfalfa Silage ◽

Additive Control

The objective was to study the effects of sugar cane molasses addition on the fermentation quality and tastes of alfalfa silage. Fresh alfalfa was ensiled with no additive (Control), 1% molasses (M1), 2% molasses (M2), and 3% molasses (M3) for 206 days. The chemical composition and fermentation characteristics of the alfalfa silages were determined, the microbial communities were described by 16S rRNA sequencing, and the tastes were evaluated using an electronic tongue sensing system. With the amount of added molasses (M), most nutrition (dry matter and crude protein) was preserved and water-soluble carbohydrates (WSC) were sufficiently used to promote the fermentation, resulting in a pH reduction from 5.16 to 4.48. The lactic acid (LA) content and LA/acetic acid (AA) significantly increased, indicating that the fermentation had turned to homofermentation. After ensiling, Enterococcus and Lactobacillus were the dominant genus in all treatments and the undesirable microbes were inhibited, resulting in lower propionic acid (PA), butyric acid (BA), and NH3-N production. In addition, bitterness, astringency, and sourness reflected tastes of alfalfa silage, while umami and sourness changed with the amount of added molasses. Therefore, molasses additive had improved the fermentation quality and tastes of alfalfa silage, and the M3 group obtained the ideal pH value (below 4.5) and the best condition for long-term preservation.

Download Full-text