摘要：The pozzolanic activity of coal gangue, which is calcining at 500 to 1 000 ℃, differs distinctly. The simplex-centroid design with upper and lower bounds of component proportion is adopted to study the compressive strength of mortars made with ternary blends of cement, activated coal gangue and fly ash. Based on the results of a minimum of seven design points, three special cubic polynomial models are used to establish the strength predicating equations at different ages for mortars. Five experimental checkpoints were also designed to verify the precision of the equations. The most frequent errors of the predicted values are within 3%. A simple and practical way is provided for determining the optimal proportion of two admixtures when they are used in concrete.

摘要：Porous concrete plays a crucial role in addressing various environmental challenges and mitigating the impacts of climate *** proves effective in reducing issues such as flooding,heat phenomena in the earth,and groundwater *** devoid of sand content,porous concrete’s key attributes lie in its permeability and compressive *** prediction of these properties is essential for cost and time savings,ensuring precise proportions of materials in the concrete *** article explores different models,including the linear model(LR),nonlinear model(NLR),and Artificial Neural Network(ANN),to predict and estimate permeability and compressive strength in porous *** analysis incorporates 139 samples from various papers and experimental studies,utilizing significant parameters and variables like water-to-cement ratio,coarse aggregate content,cement content,porosity,and curing time as input *** assessments,such as Root Mean Square Error(RMSE),Mean Absolute Error(MAE),Scatter Index(SI),OBJ value,and coefficient of determination(R^(2)),are employed to assess model *** results reveal that the ANN model outperforms other models in forecasting permeability and compressive strength of porous *** SI and OBJ value of the ANN model are lower than those of all other models,indicating superior *** robust performance of the ANN model has significant implications for construction applications,ensuring precise material proportions and contributing to the durability of porous concrete *** success of the ANN model suggests avenues for refinement,including architecture adjustments and dataset *** findings offer valuable insights into the ongoing efforts to optimize simulation techniques for predicting key properties of construction *** the other hand,the use of these models to optimize concrete mix design not only enhances efficiency but also significantly conserves raw

摘要：Lumbar degeneration leads to changes in geometry and density distribution of vertebrae,which could further influence the mechanical property and *** study aimed to quantitatively describe the variations in shape and density distribution for degenerated vertebrae by statistical models,and utilized the specific statistical shape model(SSM)/statistical appearance model(SAM)modes to assess compressive strength and fracture *** detailed SSM and SAM were developed based on the 75 L1 vertebrae of elderly men,and their variations in shape and density distribution were quantified with principal component(PC)*** vertebrae were classified into mild(n=22),moderate(n=29),and severe(n=24)groups according to the overall degree of *** computed tomography-based finite element analysis was used to calculate compressive strength for each L1 vertebra,and the associations between compressive strength and PC modes were evaluated by multivariable linear regression(MLR).Moreover,the distributions of equivalent plastic strain(PEEQ)for the vertebrae assigned with the first modes of SSM and SAM at mean±3SD were *** Leave-One-Out analysis showed that our SSM and SAM had good performance,with mean absolute errors of 0.335±0.084 mm and 64.610±26.620 mg/cm3,respectively.A reasonable accuracy of bone strength prediction was achieved by using four PC modes(SSM 1,SAM 1,SAM 4,and SAM 5)to construct the MLR ***,the PEEQ values were more sensitive to degeneration-related variations of density distribution than those of *** density variations may change the deformity type(compression deformity or wedge deformity),which further affects the fracture *** models can identify the morphology and density variations in degenerative vertebrae,and the SSM/SAM modes could be used to assess compressive strength and fracture *** above findings have implications for assisting clinicians in pathological dia

摘要：Aiming to investigate the mix design of eco-friendly UHPC with supplementary cementitious materials and coarser aggregates, we comprehensively studied the workability, microstructure, porosity, compressive strength, flexural strength, and Young’s modulus of UHPC. Relationship between compressive strength and Young’s modulus was obtained eventually. It is found that the compressive strength, flexural strength, and Young’s modulus of UHPC increase by 19.01%, 10.81%, and 5.99%, respectively, when 40 wt% cement is replaced with supplementary cementitious materials. The relationship between compressive strength and Young’s modulus of UHPC is an exponential form.

摘要：The effects of water/binder ratio （w/b） on the toughness behavior, compressive strength and flexural strength of engineered cementitious composites （ECC） were investigated. The w/b ratios of 0.25, 0.31, 0.33 and 0.37 were selected and the specimens were tested at the ages of 7 d and 28 d. The experimental results showed that there was a corresponding increase in first cracking strength, modulus of rupture, compressive strength and flexural strength with the decrease of w/b. Within the w/b range of 0.25-0.37, higher w/b was found to have improved effects on deflection, strain hardening index and toughness index of ECC. In the permission of meeting the requirement of compressive strength grade, selecting higher w/b in mix design will help to obtain robust ECC.

摘要：A technique for compensation of temperature effects in fiber grating sensors is reported. For strain sensors and other sensors related to strain such as electromagnetic sensors, a novel structure is designed, which uses two fiber Bragg gratings (FBGs) as strain differential sensor and has temperature effects cancelled. Using this technique, the stress sensitivity has been amplified and gets up to 0.226 nm/N, the total variation in wavelength difference within the range of 3-45 °C is 0.03 nm, 1/14 of the uncompensated FBG. The structure can be used in the temperature-insensitive static strain measurement and minor-vibration measurement.

摘要：Cement-based composite grouting materials were used to construct grouting cutoff wall for heavy metal contaminated soil in non-ferrous metal mining areas. Cement, fly ash, and slag as principal ingredients were mixed with water glass in different ways to produce three composite grouting materials. In order to investigate the effect of water glass mixing ratio, Baume degree, fly ash and slag contents on the mechanical properties of the composite grouting materials, particularly their gel time and compressive strength, the beaker-to-beaker method of gel time test and unconfined compressive strength test were conducted. In addition, the phase composition and microstructure of the composite grouting materials were analyzed by the X-ray diffraction（XRD） and scanning electron microscope（SEM） techniques. The test results show that their gel time increases when water glass mixing ratio and Baume degree increase. The gel time increases dramatically when fly ash is added, but decreases slightly if fly ash is partly replaced by slag. When the mixing ratio of water glass is below 20%, their compressive strength increases with the increases of the ratio; when the ratio is above 20%, it significantly decreases. The compressive strength also tends to increase as Baume degree increases, and improves if fly ash and slag are added.

摘要：The influence of source concrete (SC) with different compression strengths on the workability and mechanical properties of recycled mortar made with river sand substituted by 100% fine recycled concrete aggregates (FRCA) is experimentally investigated. The basic physical performance test shows that with the increase in SC strength, FRCA exhibit lower water absorption and crushing index, meanwhile keeping higher densities. Mechanical property tests, including compressive strength, flexural strength and uniaxial compressive stress-strain tests, show that compressive strength,flexural strength and elasticity modulus of recycled sand mortars increase roughly with the increase in SC strength. The proposed mixture design method demonstrates that all of the components can be kept as the same as those in natural mortar mixture design and FRCA must be pre-wetted before making mortar mixture. Meanwhile, the reuse of higher strength SC can ensure that recycled mortar mixtures are able to achieve similar mechanical performance when compared to natural mortar designs.

摘要：In recent years,extensive research has focused on applying machine learning(ML)techniques to predict the properties of engineered cementitious composites(ECCs).ECCs exhibit crucial characteristics such as compressive strength(CS),tensile strength(TS),and tensile strain(TSt).Accurate forecasting of these critical properties can reduce material waste,lower construction expenses,and expedite project timelines for engineers and *** study investigates mixture design components and corresponding strengths of ECCs based on only polyethylene fiber drawing from existing *** neural network(ANN)models are developed to predict CS,TS,and TSt using a dataset of 339 experimental results with twelve input *** ANN models,implemented in MATLAB,consider various hidden layers and neurons to optimize accuracy and validation metrics demonstrate the model’s high *** analysis explores individual parameter *** inspiration from this study,it would be advantageous to enhance the predictive modeling toolkit by leveraging the progress made in existing technologies,thereby driving the green and low-carbon development of civil *** approach not only improves the efficiency and sustainability of construction practices but also aligns with global environmental goals by reducing the carbon footprint associated with civil engineering projects.

摘要：Mud losses are one of the most severe problems encountered in drilling. This is commonly known as lost circulation. It can occur in naturally fractured formations and also can be induced in formations through drilling. Mud losses while drilling leading to cost overruns and HSE concerns, primary cement job failure due to not getting the cement up to the desired height resulting in subsequent sustained casing pressure and corrosion, not able to perform work over activity on certain wells due to losses. The objective of this paper is to explain extreme lost circulation problem and introduce cement plug formulation to cure or mitigate this problem. In addition, the cement plug has certain compressive strength that this is proper for use to control lost circulation in field. And finally, the application of a cement plug is described in one well of the Gas Field (National Iranian Oil Company).