Fineness Ratio Research Articles

Mechanical and durability properties of standard and high strength geopolymer concrete using particle packing theory

Aggregate packing significantly affects the characteristics of fresh and hardened concrete; aggregates having higher packing density (PD) improve these characteristics. There is a lack of research on how the PD affects the properties of geopolymer concrete (GPC). Hence, the present study includes the effect of the PD on the mechanical and durability properties of the standard and high-strength GPC. The study parameters are the binder content, the concentration of NaOH, and the fly ash to ground granulated blast furnace slag (GGBS) ratio. Six aggregate groups (like 12.5–10 mm, 10–4.75 mm, 4.75–2.36 mm, 2.36-1.18 mm, 1.18–0.6, and 0.6–0.15 mm) were investigated for the particle packing experiment, and the blended coarse:fine aggregate ratio of 55:45 which produced the highest packing density of 0.702, were used in the GPC mixes. A total of 120 cubes of size 100 mm, 30 cylinders of size 100 × 200 mm, and 30 prisms of size 100 × 100 × 500 mm were cast for 10 different mixes in the study. Sorptivity and water absorption are the tests performed for the durability studies. The result shows that GPC mixes with Particle packing theory significantly improved the compressive strength, and durability, and showed better workability. The workability of the GPC reduces by increasing the GGBS and concentration of the NaOH solution. As the GGBS proportion and the concentration of the NaOH solution increases, the concrete compressive, split, and flexural strength increases. As the binder content increases, the strength increases at first, then reduces. Increasing the GGBS content, binder content, and molarity of the NaOH accomplishes a reduction of the sorptivity coefficient and water absorption of the GPC.

Feasibility study on impact of replacement of river sand with crushed aggregate in concrete mix

The importance of utilizing stone waste, known as stone dust, in construction and infrastructure projects as a replacement for natural sand cannot be overstated. This practice holds paramount significance as it not only serves to substitute natural sand but also plays a pivotal role in reducing construction expenses. Because of the severe shortage in many locations, as well as expense and environmental concerns, an alternative is being considered. In this endeavor, the viability of incorporating stone dust as a potential substitute for fine aggregate is under meticulous investigation. In this study, M20, M30, and M40 concrete mixes were employed. The results of the tests show that stone dust may be utilized in concrete as a partial replacement for fine aggregate. The finding has been made that using stone dust increases the flexural and compressive strength of concrete. The percentage of fine aggregate replaced by stone dust (0, 20, 50, 80, and 100 percent) is explored. This paper also studied various proportions of cement concrete and stone dust (M20, M30, M40). The experimental findings revealed that adding stone dust as a fine aggregate ratio of 20%, 50%, 80%, and 100% improved the compressive properties.

Performance of self-compacting concrete cast in hot weather conditions

This work focused on how self-compacting concrete (SCC) performs in situ in hot weather conditions at an ambient temperature of about 35°C. Tests for the rheological properties and compressive and splitting tensile strength aspects were carried out. The results of SCC mix ingredients on the rheological and hardened features of SCC mix were studied. Variations in the amount of portland cement content (CC), water to cement ratio (w/c), coarse to fine aggregate ratio (C : F), chemical admixture ratio, and pozzolanic admixture ratio were considered. Optimum values were obtained for these ingredients, which satisfied the SCC rheological characteristics and gave a 28-day compressive strength of 42 MPa, and 52 MPa after 28 days and 56 days, respectively. These optimum constituent values were 450 kg·m–3 of cement, 0.45 water cementitious ratio, and a coarse to fine material ratio of 1 : 0.8, a high range superplasticizer of 2%, and a mineral admixture of either 5% silica fume or 25% fly ash as a substitute for a similar amount cement.

Evaluation of the sieve analysis effect on the efficiency of PVC waste as sand replacement in concrete mixtures

Recycling materials has become an immerging tendency as a way for preserving natural resources. The waste disposal of polymeric materials has a significant impact on the environment and public health through their practical application in civil engineering constructions. The current experimental study aims to investigate the possibility of using polyvinyl chloride (PVC) waste in concrete and also to evaluate the PVC concrete properties in comparison with ordinary concrete (OC). This investigation research involves reusing the left-over PVC tube wastes and their incorporation in concrete. Three different replacement ratios (5%, 10% and 15%) of natural sand by polyvinyl chloride were considered, taking into account two different sizes (fine and fiber) of polymeric wastes. The effects of each incorporated PVC waste on the compressive strength, and tensile strength were studied. The fresh properties of concrete were investigated by conducting a slump test. The results revealed a decrease in the workability of the fresh PVC concrete compared to ordinary concrete. It was observed that the concrete made with fiber PVC shows a lower workability (decrease of 54%) in comparison with the first one which contains fine PVC aggregates. The concrete made with fiber PVC aggregates improves the compressive strength up to 23.5%. This latter increased simultaneously with increasing the replacement ratio of PVC waste. However, the increase of fine PVC waste content caused a decrease in compressive strength till 21%. The test results also revealed that the concrete mixes with high fiber and moderate fine PVC ratios enhanced the concrete mechanical performance.

Ontology Framework for Sustainability Evaluation of Cement–Steel-Slag-Stabilized Soft Soil Based on Life Cycle Assessment Approach

Steel slag has become a promising supplementary cementitious material for soft soil stabilization. However, there is a lack of research on the integrated assessment of cement–steel-slag-stabilized soft soils (SCSs) from the performance, environmental, and economic perspectives. In this study, an ontology framework for the sustainable evaluation of SCSs was developed based on the life cycle assessment (LCA) approach, which combined a knowledge base with semantic web rules to achieve an automated decision design for soft soil stabilization, considering comprehensive benefits. The ontology framework was applied to a marine soft soil stabilization case to verify its scientificity and practicability and to evaluate the influence of the fineness, carbonation degree, and substitution ratio of steel slag on the sustainability of SCSs. The results show that, when compared to pure-cement-stabilized soil (S-C), using 10% and 20% of fine steel slag carbonated for 18 h (FSS-C-18h) as cement substitutes can significantly reduce carbon emissions and costs while achieving a similar strength performance as S-C, demonstrating the feasibility of steel slag as a sustainable supplementary cementitious material for soft soil stabilization.

Optimization of concrete mix designs toward the bond properties of steel reinforcement in self-healing concrete by Taguchi method

The bond of steel reinforcement in normal concrete has been extensively studied, while its bond properties in self-healing concrete has rarely been investigated because the main focus of developing self-healing concrete relies on the improved healing performance such water tightness and strength regain. In fact, the mix design of concrete will greatly affect the bonding. This study elaborates on the optimisation of mix designs for self-healing concrete toward the bond properties of steel reinforcement. The proposed healing agents were bacterial healing agent (BAC) and crystalline admixtures (CA). Mix design parameters include water-cement ratio (w/c) (0.40, 0.50 and 0.60), fine ratio (FR) (0.34, 0.44 and 0.54), and healing agent (HA) (BAC, CA and REF, without healing agent). The Taguchi method was used to formulate nine self-healing concrete mixes by considering three factors and three levels in the design. The compressive strengths of all different concrete mixtures were initially assessed and the pull-out tests on a single steel rebar embedded in concrete were performed in three different states of concrete (uncracked, cracked and healed). The sizes of the cracks were varied and three groups were identified: cracks with a width of 200-300, 300–400 and 400-500 μm. Water immersion was selected as the healing regime with two healing periods lasting 28 and 112 days. The Taguchi analysis and in-depth statistical evaluations were performed for optimisation purpose. Results showed that the compressive strength considerably increased as lowering the w/c, increasing the FR and incorporating the healing agents. The bond of steel reinforcement with the concrete matrix in the uncracked state improved after the BAC or CA was added into the concrete. The formation of cracks in the concrete significantly reduced the bond strength. After being subjected to healing, the bond strength slightly recovered. A longer healing time induced a better bond strength recovery. The phenomenon of crack closure was found at all healed specimens and the healing products were confirmed to be calcium carbonates.

Type 2 diabetes, hepatic decompensation, and hepatocellular carcinoma in patients with non-alcoholic fatty liver disease: an individual participant-level data meta-analysis

Data are scarce regarding the development of hepatic decompensation in patients with non-alcoholic fatty liver disease (NAFLD) with and without type 2 diabetes. We aimed to assess the risk of hepatic decompensation in people with NAFLD with and without type 2 diabetes. We did a meta-analysis of individual participant-level data from six cohorts in the USA, Japan, and Turkey. Included participants had magnetic resonance elastography between Feb 27, 2007, and June 4, 2021. Eligible studies included those with liver fibrosis characterisation by magnetic resonance elastography, longitudinal assessment for hepatic decompensation and death, and included adult patients (aged ≥18 years) with NAFLD, for whom data were available regarding the presence of type 2 diabetes at baseline. The primary outcome was hepatic decompensation, defined as ascites, hepatic encephalopathy, or variceal bleeding. The secondary outcome was the development of hepatocellular carcinoma. We used competing risk regression using the Fine and Gray subdistribution hazard ratio (sHR) to compare the likelihood of hepatic decompensation in participants with and without type 2 diabetes. Death without hepatic decompensation was a competing event. Data for 2016 participants (736 with type 2 diabetes; 1280 without type 2 diabetes) from six cohorts were included in this analysis. 1074 (53%) of 2016 participants were female with a mean age of 57·8 years (SD 14·2) years and BMI of 31·3 kg/m2 (SD 7·4). Among 1737 participants (602 with type 2 diabetes and 1135 without type 2 diabetes) with available longitudinal data, 105 participants developed hepatic decompensation over a median follow-up time of 2·8 years (IQR 1·4-5·5). Participants with type 2 diabetes had a significantly higher risk of hepatic decompensation at 1 year (3·37% [95% CI 2·10-5·11] vs 1·07% [0·57-1·86]), 3 years (7·49% [5·36-10·08] vs 2·92% [1·92-4·25]), and 5 years (13·85% [10·43-17·75] vs 3·95% [2·67-5·60]) than participants without type 2 diabetes (p<0·0001). After adjustment for multiple confounders (age, BMI, and race), type 2 diabetes (sHR 2·15 [95% CI 1·39-3·34]; p=0·0006) and glycated haemoglobin (1·31 [95% CI 1·10-1·55]; p=0·0019) were independent predictors of hepatic decompensation. The association between type 2 diabetes and hepatic decompensation remained consistent after adjustment for baseline liver stiffness determined by magnetic resonance elastography. Over a median follow-up of 2·9 years (IQR 1·4-5·7), 22 of 1802 participants analysed (18 of 639 with type 2 diabetes and four of 1163 without type 2 diabetes) developed incident hepatocellular carcinoma. The risk of incident hepatocellular carcinoma was higher in those with type 2 diabetes at 1 year (1·34% [95% CI 0·64-2·54] vs 0·09% [0·01-0·50], 3 years (2·44% [1·36-4·05] vs 0·21% [0·04-0·73]), and 5 years (3·68% [2·18-5·77] vs 0·44% [0·11-1·33]) than in those without type 2 diabetes (p<0·0001). Type 2 diabetes was an independent predictor of hepatocellular carcinoma development (sHR 5·34 [1·67-17·09]; p=0·0048). Among people with NAFLD, the presence of type 2 diabetes is associated with a significantly higher risk of hepatic decompensation and hepatocellular carcinoma. National Institute of Diabetes and Digestive and Kidney Diseases.

Investigation of the effect of nose shape and geometry at supersonic speeds for missile performance optimisation

This paper investigated and analysed the influence of the missile nose shapes and geometry on the drag force coefficients at supersonic Mach numbers ranging from 2 to 5. The nose shape investigation includes a pointed cone, pointed ogive, and blunt cone with a constant length and diameter of cylindrical afterbody. Subsequently, the nose length was manipulated to investigate how the nose geometry with different fineness ratios affected each drag component. The drag force coefficient and its components were determined using a program called MATLAB_Aerody, in which a semi-empirical approach was implemented for the calculations. The program was validated against the semi-empirical results with existing theoretical and experimental results. The comparison showed a maximum error of 3.6%. The results of the nose shape analysis show that a sharper and more slender nose with a pointy tip produces a minimal drag. Nose bluntness, however, creates considerable additional drag force due to a higher wave drag coefficient by forming detached or bow shock waves. At supersonic speeds, increasing the fineness ratio significantly reduces the drag force by drastically decreasing the wave drag coefficient with a marginal increase in the skin friction coefficients. However, the results show an insignificant additional gain for the skin friction drag and a reduction in the wave drag coefficient when the nose has a fineness ratio beyond 4.5. Furthermore, the results from both analyses show that the base drag coefficient is invariant with the nose shape and the fineness ratio. Therefore, a better missile performance can be achieved with a sharper and more slender nose shape with a higher fineness ratio.

Assessment of Air pollution in Benghazi City during February and March periods using Airvisual Outdoor Monitor

Particulate matter is a major indicator of the level of air pollution. The ratio of fine and coarse particles and particle type determine the ability of atmospheric processes and affect human health. The aim of this work is to assess the spatiotemporal variation of particulates (PM1, PM2.5, and PM10) during the monitoring period from February 2023 to March 2023 and to assess the correlations between pollutants and the impact of meteorological factors. The results showed the main average air quality index (AQI) in the February period was about 138 μg/m3, which reflected the air quality is unhealthy for sensitive groups, while the main average AQI in the March period was about 89 μg/m3, which reflected the air quality is moderate. Based on PM2.5/PM10 ratios in February the mixed particles and anthropogenic source are more common in the atmosphere and PM2.5/ PM10 ratios in March period the mixed particles and natural sources are more common in the atmosphere in Benghazi city. The February period has more pollutants than the March period due to more than type of pollution. The bivariate polar plots of temperature AQI, PM1/PM2.5, and PM2.5/PM10 were negatively correlated with temperature while positively correlated with wind speed. SE directions of wind have a major impact on increasing PM and natural pollution type concentrations in Benghazi city.

Deep neural network-based reduced-order modeling of ion–surface interactions combined with molecular dynamics simulation

With the advent of complex and sophisticated architectures in semiconductor device manufacturing, atomic-resolution accuracy and precision are commonly required for industrial plasma processing. This demands a comprehensive understanding of the plasma–material interactions—particularly for forming fine high-aspect ratio (HAR) feature patterns with sufficiently high yield in wafer-level processes. In particular, because the shape distortion in HAR pattern etching is attributed to the deviation of the energetic ion trajectory, the detailed ion–surface interactions need to be thoroughly investigated. In this study, molecular dynamics (MD) simulations were utilized to obtain a fundamental understanding of the collisional nature of accelerated Ar ions on the fluorinated Si surface that may appear on the sidewall of the HAR etched hole. High-fidelity data for ion–surface interaction features representing the energy and angle distributions (EADs) of sputtered atoms for varying degrees of surface F coverage and ion incident angles were obtained via extensive MD simulations. A deep learning-based reduced-order modeling (DL-ROM) framework was developed for efficiently predicting the characteristics of the ion–surface interactions. In the ROM framework, a conditional variational autoencoder (AE) was implemented to obtain regularized latent representations of the distributional data with the condition of the governing factors of the physical system. The proposed ROM framework accurately reproduced the MD simulation results and significantly outperformed various DL-ROMs, such as AE, sparse AE, contractive AE, denoising AE, and variational AE. From the inferred features of the sputtering yield and EADs of sputtered/scattered species, significant insights can be obtained regarding the ion interactions with the fluorinated surface. As the ion incident angle deviated from the glancing-angle range (incident angle >80°), diffuse reflection behavior was observed, which can substantially affect the ion transport in the HAR patterns. Moreover, it was hypothesized that a shift in sputtering characteristics occurs as the surface F coverage varies, based on the inferred EADs. This conjecture was confirmed through detailed MD simulations that demonstrated the fundamental relationship between surface atomic conformations and their sputtering behavior. Combined with additional atomistic-scale investigations, this framework can provide an efficient way to reveal various fundamental plasma–material interactions which are highly demanded for the future development of semiconductor device manufacturing.

Prediction of concrete strength using response surface function modified depth neural network.

In order to overcome the discreteness of input data and training data in deep neural network (DNN), the multivariable response surface function was used to revise input data and training data in this paper. The loss function based on the data on the response surface was derived, DNN based on multivariable response surface function (MRSF-DNN) was established. MRSF-DNN model of recycled brick aggregate concrete compressive strength was established, in which coarse aggregate volume content, fine aggregate volume content and water cement ratio are influencing factors. Furthermore, the predictive analysis and extended analysis of MRSF-DNN model were carried out. The results show that: MRSF-DNN model had high prediction accuracy, the correlation coefficient between the real values and the forecast values was 0.9882, the relative error was between -0.5% and 1%. Furthermore, MRSF-DNN had more stable prediction ability and stronger generalization ability than DNN.

Impact of Compression Casting Technique on the Mechanical Properties of 100% Recycled Aggregate Concrete

The research work presented in this manuscript focused on the comparative examination of the influence of the Compression Casting Technique (CCT) and the conventional casting method (i.e., compaction through vibration) on the performance of 100% Recycled Aggregate Concrete (RAC). The minimum target compressive strength of 100% RAC was 15 MPa keeping in view its application in the manufacturing of load-bearing concrete masonry units. A total of 28 concrete compositions were prepared by varying the coarse to fine aggregates ratio (i.e., 70:30 and 60:40), cement content (10% and 15%) by weight of total aggregates, casting technique, and applied pressure for compression casting (i.e., 25, 35, and 45 MPa). The concrete compositions were tested to determine their density, compressive strength, Elastic Modulus (EM), and Ultrasonic Pulse Velocity (UPV). For comparison, samples of Natural Aggregate Concrete (NAC) were also tested for the same properties. The results highlighted the positive impact of CCT on the properties of 100% RAC. The compressive strength and EM of fully RAC was increased by 20–80% and 15–50%, respectively, by changing casting method from vibration to CCT. At casting pressure of 35 MPa and 15% cement, compressed 100% RAC exhibited compressive strength higher than vibrated NAC. The UPV value exhibited by 100% RAC was increased by changing the casting technique. The analytical models were proposed using regression analysis of experimental results to predict compressive strength and EM of compressed 100% RAC and NAC. These proposed models were evaluated using statistical parameters, i.e., average absolute error (AAE) and mean (M) and found to be able to predict the compressive strength and EM of RAC with reasonable accuracy as compared to the analytical models already existing in the literature. This study finally concluded that through CCT, 100% RAC with low cement content could achieve minimum target compressive strength of 15 MPa. The development and use of compressed load-bearing 100% RAC construction units would help to achieve sustainability in construction.

Fineness Ratio Effects on the Flow Past an Axisymmetric Body at High Incidence

The flow past an axisymmetric body at a sufficiently high angle of attack becomes asymmetric and unsteady. Several authors identified three different flow regions for bodies of large fineness ratio at low subsonic flow and high incidence: a steady region in the forebody and two unsteady regions in the rear body. Unsteady Reynolds Averaged Navier–Stokes (URANS) codes with eddy viscosity turbulence models or Reynolds stress turbulence models fail to capture the unsteady flow region. These methods are overly dissipative and resolve only frequencies far lower than turbulent fluctuations. Scale-Adaptive-Simulation (SAS) provides an alternative method to afford the problem of these massively separated flows at high Reynolds numbers without addressing the problem to Large Eddy Simulation (LES). This paper applies SAS to study the effect of slenderness on the flow. The numerical solutions show that the flow becomes more unstable as the fineness ratio increases, and the three flow regions are clearly recognizable. For low fineness ratios, only one of the two unsteady regions is visible. The good agreement between the sectional forces and pressure coefficients with their corresponding experimental data for an ogive-cylinder configuration allows an analysis of the flow structure with a fair degree of confidence.

Energy-Based Aerodynamic Loss and Recovery Characteristics of Adiabatic and Heated Fuselages

An energy-based aerodynamic analysis of the mechanical loss generation and potential energy/exergy recovery mechanisms is carried out for adiabatic and heated 2D axisymmetric flows over fuselage-shaped axisymmetric bodies. A generality of these mechanisms is obtained from dimensional analysis by appropriately scaling the freestream Reynolds and Mach numbers, while varying a reference fuselage’s fineness ratio. Thermo-aerodynamic implications and synergies of boundary-layer heating on the loss distribution, energy, and heat exergy recovery potentials are further considered for varying wall temperature ratios. The result is a clear identification of partial dynamic similarity and heat transfer effects on flow mechanisms such as shear layers, separation bubbles, and shockwaves of axisymmetric flows, and subsequent implications on loss distribution and energy recovery characteristics relating to boundary-layer ingestion. The analysis indicates that dissipating heat from aircraft surfaces aids, circumstantially, to drag reduction of unpowered fuselage bodies and increases, relative to the adiabatic, the recoverable energy fraction available for the boundary-layer ingestion propulsor, by strategically manipulating the loss distribution, while removing excess heat from the aircraft’s subsystem (batteries, fuel cells). Finally, an approach to assess the feasibility of exergetic heat recuperation as a possible means of useful work extraction and improved aerodynamic performance is explicitly introduced and discussed in the paper.

A GPU-accelerated adaptive particle refinement for multi-phase flow and fluid-structure coupling SPH

In this paper, a graphical processing unit (GPU) implementation of adaptive particle refinement (APR) in the Smoothed Particle Hydrodynamics (SPH) framework is used to simulate the multi-phase flow and fluid-structure coupling problems. The multi-phase flow and fluid-structure coupling SPH models based on the Riemann solver are presented and the local particle refinement technique based on the axis-aligned square refinement pattern is adopted to split particles. A particle shifting technique constructing virtual fine particles (VFP-PST) is proposed to regularize the particle distribution for numrical accuracy and stability. To facilitate the device memory throughput efficiently, a dynamic resource management algorithm is used to implement GPU-accelerated adaptive particle refinement. Precision analysis shows the effect of the smooth length ratio of fine and coarse particles on numerical accuracy. Different tests have demonstrated that the proposed GPU-accelerated IAPR is accurate and stable and provides a promising approach to simulate the multi-phase flow and fluid-structure problems with low computational cost and comparable precision when compared with uniform particles.

Influence of α-Si3N4 coarse powder on densification, microstructure, mechanical properties, and thermal behavior of silicon nitride ceramics

Silicon nitride (Si3N4) ceramics, with different ratios of fine and coarse α-Si3N4 powders, were prepared by spark plasma sintering (SPS) and heat treatment. Further, the influence of coarse α-Si3N4 powder on densification, microstructure, mechanical properties, and thermal behavior of Si3N4 ceramics was systematically investigated. Compared with fine particles, coarse particles exhibit a slower phase transition rate and remain intact until the end of SPS. The remaining large-sized grains of coarse α-Si3N4 induce extensive growth of neighboring β-Si3N4 grains and promote the development of large elongated grains. Noteworthy, an appropriate number of large elongated grains distributed among fine-grained matrix forms bimodal microstructural distribution, which is conducive to superior flexural strength. Herein, Si3N4 ceramics with flexural strength of 861.34 MPa and thermal conductivity of 65.76 W m−1 K−1 were obtained after the addition of 40 wt% coarse α-Si3N4 powder.

Ultrafast response self-powered UV photodetectors based on GaS/GaN heterojunctions

Self-powered ultraviolet (UV) photodetectors (PDs) based on GaN have been of great importance in the application of UV communication, thanks to its wide direct bandgap and strong resistance to irradiation. However, current self-powered GaN-based heterojunction UV photodetectors could not meet the requirement of fast photoresponse. Herein, type-II pn heterojunction GaS/GaN-based self-powered PDs have been proposed with a naturally p-type doping GaS thin film grown on n-type GaN via chemical vapor deposition. The electronic and optical properties of GaS/GaN heterojunction were investigated via experiments and the density functional theory. Afterward, as-prepared GaS/GaN-based PDs reveal an excellent self-powered photosensitivity/detectivity of 6.26 mA W−1/8.29 × 109 Jones at 0 V at 365 nm, ultrafast response speed with a rise/fall time of 48/80 μs as well as an amazing rejection ratio (R365 nm/R500 nm) of 3.42 × 104, and a fine rectification ratio of 105.9. This work provides a feasible method to synthesize high-performance GaS/GaN heterojunctions and demonstrates their enormous potential in ultrafast response self-powered UV photodetection.

Effect of Cement Type and Water-to-Cement Ratio on Fresh Properties of Superabsorbent Polymer-Modified Cement Paste

Superabsorbent polymer (SAP) is a material with the ability to absorb liquid and desorb liquid from and to the environment, and it can ensure the internal curing of cementitious composites. Although the fresh state properties of SAP-modified mixtures (SAPCP) are affected and have been investigated nowadays, the rheological properties of SAPCP are still a virgin field and they are worth studying. Hence, the current study was aimed and conducted to observe what occurred if cements with different chemical compositions, various ratios of water/cement (w/c) and SAP were used together. Accordingly, CEM I 42.5R, CEM II/A-LL 42.5R and CEM IV/B (P) 32.5R were selected as binders in the mixtures, and w/c ratios were 0.40 and 0.50 for SAPCPs. In total, 24 mixtures were designed, produced and tested in the laboratory and spreading table tests, Vicate tests, viscosity tests and shear tests were conducted on the fresh state of the mixtures to observe the fresh behavior of SAPCPs. As a result, it was determined that the SAP, cement and w/c combinations considered in the article were effective on SAPCP fresh properties and rheology. However, it was determined that the use of high amounts of SAP in the mixture, high cement fineness and high oxide ratios in the cement (ratios of silicon dioxide/calcium oxide and aluminum oxide/calcium oxide) negatively affected not only the fresh state properties, but also the rheology. Moreover, the coexistence of the aforementioned negative conditions was the most unfavorable situation: high SAP ratio + high cement fineness + high oxide ratio in SAPCP. For these reasons, it was concluded that cement fineness and chemical composition should be taken into account in the rheology/workability-based design of SAPCPs. Then, the SAP content can be regulated for design purposes.

Design and parameter optimization of a biomimetic jellyfish origami mechanism (BJOM) based on waterbomb tessellations

In this paper, a biomimetic jellyfish origami mechanism (BJOM) based on waterbomb tessellations is designed. Its geometric model is established, and its kinematic equation is derived. Its volume ratio and fineness ratio that characterize the morphological characteristics are analyzed. The maximum volume ratio and the maximum fineness ratio range were taken as the two optimization objectives, respectively. And two independent single-objective optimization models were established to optimize the structural parameters of the BJOM. Compared with the example before optimization, the results of the two optimization models have greatly improved the range of fineness ratio and the volume ratio. Finally, three factors about fineness ratio, volume ratio and material consumption were comprehensively considered to establish a three-objective optimization model. The results of these three optimization models compared is shown: the BJOM after three-objective comprehensive optimization has better comprehensive performance than the former two optimization schemes. It shows the feasibility of the optimization method and the superiority of the optimization design.

Sequence-paleogeography and coal accumulation of the Late Carboniferous – Early Permian paralic successions in western Shandong Province, northern China

The coal-bearing strata of the Late Carboniferous to the Early Permian in western Shandong Province, northern China, were deposited within a range of paralic facies associations spanning from marine offshore carbonate shelf to fluvial and delta, which constituted a general paralic cratonic setting. In this paper, the sedimentary characteristics, sequence stratigraphy, paleogeography, and coal accumulation of the Benxi, Taiyuan and Shanxi formations of the Moscovian to Sakmarian age are studied by using data of outcrops, borehole cores, and geophysical loggings. A total of 14 different lithofacies are identified, with lithologies including sandstones, siltstones, mudstones, and bioclastic limestones, and grouped into fluvial, delta, tidal bar-lagoon, and offshore shelf facies associations. Furthermore, the key sequence boundaries represented by regional unconformity, incised valley erosional surface, switching surface of transgressive direction, stratigraphic color change surface marking the abrupt change of environment, and paleosol horizon have been recognized. Based on these sequence boundaries, three third-order sequences (S1, S2, S3 in ascending order) and corresponding lowstand, transgressive, and highstand systems tracts are subdivided. S1 corresponds to the Benxi Formation and the lower part of Taiyuan Formation, S2 corresponds to the middle and upper parts of Taiyuan Formation, and S3 corresponds to the Shanxi Formation. The lithofacies paleogeography maps of three sequences are reconstructed based on the contours of a variety of lithological parameters including strata thickness, limestone thickness, limestone percentage content, coarse (sandstone)/fine (siltstone and mudstone) ratio, and total coal thickness. S1 and S2 were developed with the offshore carbonate shelf paleogeographic units and the tidal bar – lagoon paleogeographic units, and S3 was developed with delta and fluvial units. In general, the western Shandong experienced transgression in the S1, transgression direction switching between S1 and S2, transgression again in S2, and then regression in the S3 during the Late Carboniferous to the Early Permian. Most significant coal accumulation occurred in the S3, followed by S1 and then S2. The coal accumulation centers of S1 were mainly distributed in Liaocheng, Feicheng, Jining regions in the west of the western Shandong where the tidal bar and lagoon were developed, those of S2 were mainly distributed in Tai'an, Jining and Tengzhou regions in the central part of the western Shandong, where the lagoon and tidal flat were developed, and those of S3 were mainly distributed in Heze, Jining, Tengzhou and Zaozhuang regions of the southern part of the western Shandong where the delta environment was developed. Overall, the high accommodation setting of S1 and S2, represented by the Benxi and Taiyuan formations, favors thick coal accumulation in the early TST, while the low accommodation setting S3, represented by the Shanxi Formation, favors thick coal accumulation in the middle and late TST. The research results of this study can be used in the evaluation of the favorable areas for the exploration and development of the deep-buried coal and CBM resources in western Shandong Province.