Mechanical properties and energy evolutions of burst-prone coal samples with holes and fillings

During the mining process of impact-prone coal seams,drilling pressure relief can reduce the impact propensity of the coal seam,but it also reduces the integrity and strength of the coal mass at the side of the roadway.Therefore,studying the mechanical properties and energy evolution rules of coal samples containing holes and filled structures has certain practical significance for achieving coordinated control of coal mine rockburst disasters and the stability of roadway surrounding rocks.To achieve this aim,seven types of burst-prone coal samples were prepared and subject to uniaxial compression experiments with the aid of a TAW-3000 electro-hydraulic servo testing machine.Besides,the stress–strain curves,acoustic emission signals,DIC strain fields and other data were collected during the experiments.Furthermore,the failure modes and energy evolutions of samples with varying drilled hole sizes and filling materials were analyzed.The results show that the indexes related to burst propensity of the drilled coal samples decline to some extent compared with those of the intact one,and the decline is positively corelated to the diameter of the drilled hole.After hole filling,the strain concentration degree around the drilled hole is lowered to a certain degree,and polyurethane filling has a more remarkable effect than cement filling.Meanwhile,hole filling can enhance the strength and deformation resistance of coal.Hole drilling can accelerate the release of accumulated elastic strain energy,turning the acoustic emission events from low-frequency and high-energy ones to high-frequency and low-energy ones,whereas hole filling can reduce the intensity of energy release.The experimental results and theoretical derivation demonstrate that hole filling promotes coal deformability and strength mainly by weakening stress concentration surrounding the drilled holes.Moreover,the fillings can achieve a better filling effect if their elastic modulus and Poisson’s ratio are closer to those of the coal body.

Frost heave control of fine round gravel fillings in deep seasonal frozen regions

Fine round gravel soil is widely employed in the subgrade of high and thawing. The lower the fines content in fine round gravel soil, but compaction difficulty increases. This study is to obtain the speed railways in cold regions to prevent frost heaving the smaller the quantities of frost heaving and thawing, optimum fines content and limited frost heaving and thawing. The fine round gravel soil filling （FRGSF） used in the Harbin-Qiqihaer Passenger Dedicated Line is taken as the study object. Influence of fines content on optimum water content, maximum dry density and frost heaving properties of FRGSF were studied by means of compaction and frost heaving tests. Results show that the maximum dry density of the FRGSF increases first and then decreases with an increase of fines content, namely there is an optimum fines content for easy compaction. The method of surface-vibratory instrument is fit for coarse-grained soils, and wet state of coarse-grained soil is in favor of compaction. Considering the relationship of fines content with maximum dry density and the frost heaving ratio of FRGSF, the fines content should be limited to within the range of 9%-10%, so that the frost heaving ratio is less than 1%, and the FRGSF is easily compacted. Water supply is proved to be an important factor influencing the amount of frost heaving of FRGSF. We also conclude that in the field, it is imperative to control waterproofing and drainage measures.

There is plenty of space in the MXene layers: The confinement and fillings

MXenes have emerged as a new kind of 2D transition metal carbides,nitrides and carbonitrides.Origined from the unique 2D structure with a luxuriant combination of elements,MXenes drive a series of the investigations related to energy storage and conversion,biometrics and sensing,lighting,purification and separation.For 2D layered MXene materials,the interspacing confined by the independent MXenes layers affords a distinct confinement space,which is similar to a nanoreactor that can be utilized for the storage of ions,nanoparticles,nanowires,and the materials with 2D or 3D structure.These fillings confined by MXene layers afford new opptunities for achieving improved properties and performance via complementary natural features,further the synergistic effect.Herein,we summarize the recent reports concerning with the confinded MXenes spacing and the fillings.The modification of interlayer distance lead by the intercalants were explored.We expect that our review may offer the route for a series of ongoing studies to address the MXenes.

The Sequence Architecture of Volcanic Basin Fillings-An Example From Xujiaweizi Faulted Depression In Songliao Basin

The basin filling geometric pattern of volcanic eruptive rocks depends on both of the eruptive locations in a basin and structural styles of fault terraces. It is divided into three types by eruptive locations and occurrences of eruptive rocks, including the pattern of eruption along fault and occurrence (PEAFO), the pattern of eruption on footwall of a fault and occurrence (PEOFO) and the pattern of eruption on hangingwall of fault and occurrence (PEOHO) in Xujiaweizi fault depression of Songliao basin, Northeast of China. Those basin filling patterns of volcanic eruptive rocks are of specific geometric characteristics controlling or affecting sedimentation, geometry of sedimentary body and sequence architecture during a sequence evolution. The study shows that the volcanic rocks developed at different stages of lowstand, transgressive and highstand can give different controls or affects on the sequence architecture.

Effect of expansive fillings on fracture seepage

Based on an investigation of the damage process of fractures filled with expansion media,samples of filling media collected on the spot,were obtained. The physical water properties of fracture fillings were tested by a WZ-2 type Dilatometer. Given our test results of the hydrated properties of fracture fillings and the mechanical parameters of altered rock mass collected from the Daye Iron Mine and comparisons between the expansion stress of fracture fillings and mechanical parameters of altered rock mass,the effects of the mechanical response of fillings on fracture seepage are discussed. The results show that the ratio of filling swell pressure to tensile strength of altered rock specimen varied between 11.79 and 36.77 and the ratio of filling swell pressure to shear strength of these rock specimen ranged from 72.11 to 171.18. Therefore,fillings have an important effect on fracture seepage,and the effect of deformation of the fracture caused by swell pressure of the filling mechanics cannot be ignored either. The multiple hydraulic coupling effects of fillings on the impact of fracture permeability are discussed according to theoretical analyses. It is shown that the effect of expansion of fracture fillings greatly affects the deformation of altered rock masses. Both tensile effect and shear effect produced by fracture fillings greatly increase the permeability of fractures. The plastic and liquefaction effects of fracture fillings also improve the permeability of fractures. On the basis of this analysis,a mechanical seepage model of filled fracture is established.

Effect of granite gravel content on improved granular mixtures as railway subgrade fillings

The improved granular mixtures are widely used as the fillings of railway 8ubgrade, and in order to investigate the effect of coarse grain content on granular mixtures, a series of field tests were conducted. The experimental results indicate that the permeability coefficient increases significantly with the increment of granite gravel content, especially in the range of 60%-70%. Thcrc exists a coarse grain content limit defined as 53%-58.5% to reform the permeable granular skeleton. Beyond this limit, the permeable granular skeleton is efficiently formed, and the macro pores between the separate gravels are partially filled, which is the explanation lbr the permeability increase. The investigations indicate the subgrade resistance modulus （ks0, Ev2, and Evd） depends on the granite gravel content, and the resistance modulus increases significantly beyond granite gravel content of 50%. The skeletons of granitc gravel clayey sand mixture change in the long-term deformation objected to the train-induced dynamic load, which involves three main repeated and circular deformation stages. Generally, the long-time deformation is explained as the gravel crushing and filling the internal porous space with crushed gravel fragments. Through these investigations, the C40-G60 or C30-G70 is recommended as an optimum soil mixture for the good permeability and high resistance modulus.

Direct shear tests of coarse-grained fillings from high-speed railway subgrade in cold regions

In order to study the shear behavior of coarse-grained fillings taken from the subgrade bottom layer of a cold region high-speed railway,large scale direct shear tests were conducted with different normal pressures,water contents and temperatures.The results indicate that the relationship between shear displacement and shear stress changed from strain-softening at lower normal pressures to strain-hardening at higher normal pressures,in both unfrozen and frozen states.This phenomenon was mainly due to the shear dilatation deformation effect.The shear displacement-shear stress curves show similar stages.Besides,the shear stress rapidly increased and there was not an increment in the shear displacement during the initial stage of the shear process in the frozen state.In both the unfrozen or frozen states at the same water contents,the shear strength increased with increasing normal pressure.

Fluid filtration and dye leakage testing of Resilon/Epiphany and guttapercha/Pulp Canal Sealer root canal fillings

The aim of the present study was to compare sealing abilities of Resilon/Epiphany (R/E) with those of guttapercha and Kerr Pulp Canal Sealer EWT (GP/PCS). 50 single rooted teeth were randomly divided into 2 groups (n = 22) (R/E;GP/PCS), and 2 control groups (n = 3) (Positive, Negative). Fluid flow rate through the filled roots was measured using a fluid filtration device. The same specimens were immersed in a 2% Methylen Blue Solution. Roots were embedded in clear epoxy resin and cross sectionet at 1 mm intervals along the length of the root. Circumferential dye penetration was evaluated at 40× magnification. Fluid filtration of teeth obturated with the R/E system (0.085 [0.057, 0.113] μL·min-1), and dye penetration test showed no statistically significant difference compared to those obturated with GP/PCS (0.113 [0.057, 0.141] μL·min-1). Within the limits of the present study, there is no statistically significant difference between R/E and GP/PCS sealing abilities.

Development of Machine Vision-Based Algorithm for Counting and Discriminating Filled and Unfilled Paddy Rice in Overlapping Mode

In this study, a new method based on image processing was presented to count and discriminate paddy rice, even when they overlapped. This method was performed in three steps. In the first step, using a reference image that excludes any overlapping paddy rice, the average area, standard deviation, and a threshold value for paddy rice were determined.

Study of the spatial growth of stimulated Brillouin scattering in a gas-filled hohlraum via detecting the driven ion acoustic wave

In an experiment performed on the Shenguang-III prototype laser facility, collective Thomson scattering (TS) is used to study the spatialgrowth of stimulated Brillouin scattering (SBS) in a gas-filled hohlraum by detecting the SBS-driven ion acoustic wave. High-quality timeresolved SBS and TS spectra are obtained simultaneously in the experiment, and these are analyzed by a steady-state code based on theray-tracing model. The analysis indicates that ion–ion collisions may play an important role in suppressing SBS growth in the Au plasma;as aresult, the SBS excited in the filled gas region is dominant. In the early phase of the laser pulse, SBS originates primarily from the high-densityplasma at the edges of the interaction beam channel, which is piled up by the heating of the interaction beam. Throughout the duration of thelaser pulse, the presence of the TS probe beam might mitigate SBS by perturbing the density distribution around the region overlapping withthe interaction beam.

Treatment of Synovial Cysts in Relation to the Tibial Tunnel of Anterior Cruciate Ligament Grafts by Filling the Tunnel with Acrylic Cement

Introduction: Synovial cyst of the tibial tunnel in connection with anterior cruciate ligament (ACL) reconstruction is a rare but particularly troublesome complication. Medical treatment is often doomed to failure, and surgical treatment usually consists of excising the cyst and filling the tunnel with bone. The aim of this study was to evaluate the results of filling the tunnel with acrylic cement. Hypothesis: Filling the tibial bone tunnel with acrylic cement should eliminate communication between the joint cavity and the pre-tibial surface and prevent cyst recurrence. Patients and Methods: This retrospective series is composed of 13 patients, 9 men and 4 women, mean age 48.5 years (31 to 64) operated on between 2011 and 2019 for an intra- and extraosseous synovial cyst consecutive to the tibial tunnel of an ACL graft. Between 1983 and 2016, 12 of the patients had had a bone graft without bone block fixation (DI-DT or Mac Intosh) and one patient, a bone-bone transplant (KJ). The cyst was of variable size, located on the anteromedial aspect of the proximal end of the tibia, and often painful, warranting consultation. At the time of the initial operation, 9 patients had undergone meniscectomies (6 medial, 2 lateral, 1 double). In 7 knees, there were 7 cartilage lesions in the femorotibial and/or patellofemoral compartments (one stage 1 lesion, 2 stage 2 lesions, 4 stage 3 lesions, and no stage 4 lesions). Only 2 knees had neither cartilage nor meniscus lesions. After curettage of the bone tunnel /− removal of the non-resorbed or PEEK interference screw, the tunnel was filled with acrylic cement /− reinforced with a ligament staple to prevent expulsion. All patients underwent regular follow-up consultations until recovery. Results: At a maximum follow-up of 8 years, only 1 cyst recurred, representing a 7.69% failure rate. It was reoperated with another technique, which involved filling the tibial bone tunnel with bone graft taken from a half-bank head. After recovery, the cyst healed definitively. All patients were able to return to their previous activity within 15 days of surgery. Conclusion: Filling the tibial tunnel with acrylic cement reinforced /− with a ligament staple is a reliable and rapid solution for the treatment of intra- and extra-articular synovial cysts in relation to the tibial tunnel of ACL grafts.

Grain-filling strategies of wheat of contrasting grain sizes under various planting patterns and irrigation levels

In a study comparing grain filling and yield in a large-and a small-grain-size wheat cultivar under two planting patterns and two irrigation regimes,plastic-covered ridge and furrow planting with sprinkler irrigation increased grain filling and yield in both cultivars.The largest contributors to grain yield were an extended active grain-filling period in Shuangda 1 and an increased mean grain-filling rate in XN538.

Enhancing the Robustness of Rib-Groove Filling and Strain Homogeneity in the Isothermal Forging of Titanium Alloy Multi-Rib Components

Isothermal forging stands as an effective technology for the production of large-scale titanium alloy multi-rib components.However,challenges have persisted,including die underfilling and strain concentration due to the complex material flow and heterogeneous deformation within the forging die cavity.While approaches centered on optimized billet designs have mitigated these challenges,uncertainties in process parameters continue to introduce unacceptable variations in forming accuracy and stability.To tackle this issue,this study introduced a multi-objective robust optimization approach for billet design,accounting for the multi-rib eigenstructure and potential uncertainties.The approach includes finite element(FE)modeling for analyzing the die-filling and strain inhomogeneity within the multi-rib eigenstructure.Furthermore,it integrated image acquisition perception and feed back technologies(IAPF)for real-time monitoring of material flow and filling sequences within die rib-grooves,validating the accuracy of the FE modeling.By incorporating dimensional parameters of the billet and uncertainty factors,including friction,draft angle,forming temperature,speed,and deviations in billet and die,quantitative analyses on the rib-groove filling and strain inhomogeneity with fluctuation were conducted.Subsequently,a dual-response surface model was developed for statistical analysis of the cavity filling and strain homogeneity.Finally,the robust optimization was processed using a non-dominated sorting genetic algorithm II(NSGA-II)and validated using the IAPF technologies.The proposed approach enables robust design enhancements for rib-groove filling and strain homogeneity in titanium alloy multi-rib components.

Effects of water and nitrogen rate on grain-filling characteristics under high-low seedbed cultivation in winter wheat

A high-efficiency mode of high-low seedbed cultivation(HLSC)has been listed as the main agricultural technology to increase land utilization ratio and grain yield in Shandong Province,China.However,limited information is available on the optimized water and nitrogen management for yield formation,especially the grain-filling process,under HLSC mode.A three-year field experiment with four nitrogen rates and three irrigation rates of HLSC was conducted to reveal the response of grain-filling parameters,grain weight percentage of spike weight(GPS),spike moisture content(SMC),and winter wheat yield to water and nitrogen rates.The four nitrogen rates were N1(360 kg ha^(-1) pure N),N2(300 kg ha^(-1) pure N),N3(240 kg ha^(-1) pure N),and N4(180 kg ha^(-1) pure N),respectively,and the three irrigation quotas were W1(120 mm),W2(90 mm),and W3(60 mm),respectively.Results showed that the determinate growth function generally performed well in simulating the temporal dynamics of grain weight(0.989<R^(2)<0.999,where R2 is the determination coefficient).The occurrence time of maximum filling rate(T_(max))and active grain-filling period(AGP)increased with the increase in the water or nitrogen rate,whereas the average grain-filling rate(G_(mean))had a decreasing trend.The final 1,000-grain weight(FTGW)increased and then decreased with the increase in the nitrogen rates and increased with the increase in the irrigation rates.The GPS and SMC had a highly significant quadratic polynomial relationship with grain weight and days after anthesis.Nitrogen,irrigation,and year significantly affected the T_(max),AGP,G_(mean),and FTGW.Particularly,the AGP and FTGW were insignificantly different between high seedbed(HLSC-H)and low seedbed(HLSC-L)across the water and nitrogen levels.Moreover,the moderate water and nitrogen supply was more beneficial for grain yield,as well as for spike number and grain number per hectare.The principal component analysis indicated that combining 240-300 kg N ha^(-1) and 90^(-1)20 mm irrigation quota could improve grain-filling efficiency and yield for the HLSC-cultivated winter wheat.

ISO 16521:2024 on concrete-filled steel tubular hybrid structures released

Recently, the international standard ISO 16521:2024, Design of concrete-filled steel tubular(CFST) hybrid structures, was issued, which is the first ISO standard in this field.Based on the fruitful research results in the field of CFST hybrid structures and the rich experience of multiscenario application in engineering, China has contributed to the development of ISO 16521:2024 with leading efforts.The standard provides guidelines for the design, construction, and inspection of CFST hybrid structures.

A review of mechanical deformation and seepage mechanism of rock with filled joints

Various defects exist in natural rock masses,withfilled joints being a vital factor complicating both the mechanical characteristics and seepage mechanisms of the rock mass.Filled jointed rocks usually show mechanical properties that are weaker than those of intact rocks but stronger than those of rocks with fractures.The shape of the rock,filling material,prefabricatedfissure geometry,fissure roughness,fissure inclination angle,and other factors mainly influence the mechanical and seepage properties.This paper systematically reviews the research progress andfindings onfilled rock joints,focusing on three key aspects:mechanical properties,seepage properties,andflow properties under mechanical response.First,the study emphasizes the effects of prefabricated defects(shape,size,filling material,inclination angle,and other factors)on the mechanical properties of the rock.The fracture extension behavior of rock masses is revealed by the stress state of rocks withfilled joints under uniaxial compression,using advanced auxiliary test techniques.Second,the seepage properties of rocks withfilled joints are discussed and summarized through theoretical analysis,experi-mental research,and numerical simulations,focusing on organizing the seepage equations of these rocks.The study also considers the form of failure under stress-seepage coupling for both fullyfilled and partiallyfilledfissured rocks.Finally,the limitations in the current research on the rock withfilled joints are pointed out.It is emphasized that the specimens should more closely resemble real conditions,the analysis of mechanical indexes should be multi-parameterized,the construction of the seepage model should be refined,and the engineering coupling application should be multi-field-multiphase.

Heterogeneous information phase space reconstruction and stability prediction of filling body–surrounding rock combination

Traditional research believes that the filling body can effectively control stress concentration while ignoring the problems of unknown stability and the complex and changeable stress distribution of the filling body–surrounding rock combination under high-stress conditions.Current monitoring data processing methods cannot fully consider the complexity of monitoring objects,the diversity of monitoring methods,and the dynamics of monitoring data.To solve this problem,this paper proposes a phase space reconstruction and stability prediction method to process heterogeneous information of backfill–surrounding rock combinations.The three-dimensional monitoring system of a large-area filling body–surrounding rock combination in Longshou Mine was constructed by using drilling stress,multipoint displacement meter,and inclinometer.Varied information,such as the stress and displacement of the filling body–surrounding rock combination,was continuously obtained.Combined with the average mutual information method and the false nearest neighbor point method,the phase space of the heterogeneous information of the filling body–surrounding rock combination was then constructed.In this paper,the distance between the phase point and its nearest point was used as the index evaluation distance to evaluate the stability of the filling body–surrounding rock combination.The evaluated distances(ED)revealed a high sensitivity to the stability of the filling body–surrounding rock combination.The new method was then applied to calculate the time series of historically ED for 12 measuring points located at Longshou Mine.The moments of mutation in these time series were at least 3 months ahead of the roadway return dates.In the ED prediction experiments,the autoregressive integrated moving average model showed a higher prediction accuracy than the deep learning models(long short-term memory and Transformer).Furthermore,the root-mean-square error distribution of the prediction results peaked at 0.26,thus outperforming the no-prediction method in 70%of the cases.

Analysis of the Effectiveness of Modified Non- Traumatic Filling Technology in the Treatment of Pediatric Dental Caries

Objective:To analyze the effectiveness of modified non-traumatic filling technology in the treatment of pediatric dental caries.Methods:Ninety-seven children with dental caries who were treated in our hospital(Panyu Maternal and Child Care Service Center of Guangzhou)from January 2022 to December 2023 were selected and randomly divided into two groups,with 48 cases in the experimental group and 49 in the control group.The experimental group was treated with modified non-traumatic filling techniques,while the control group was treated with conventional filling techniques.Observation indicators such as the total effectiveness of the treatment,incidence of adverse events,treatment compliance,and pain scores were analyzed after the intervention.Result:After intervention,the total effectiveness of the treatment in the experimental group was higher than that in the control group(P<0.05).The incidence of adverse events in the experimental group was lower than that of the control group(P<0.05).The treatment compliance of patients in the experimental group was higher than that in the control group(P<0.05).The pain score of the experimental group was lower than that of the control group(P<0.05).Conclusion:The application of modified non-traumatic filling technology in the treatment of pediatric dental caries showed good therapeutic outcomes.After the intervention,the child’s symptoms were significantly alleviated,the incidence of adverse events such as filling material falling off was reduced,their compliance was improved,and the pain was relieved.This procedure is worth to be promoted for clinical application.

L形冷弯薄壁型钢组合钢管混凝土柱轴压性能

为解决异形钢管混凝土柱阴角对其承载力的影响,提出了用1个冷弯薄壁方钢管和2个U形钢管焊接成L形钢管,内填充混凝土形成L形冷弯薄壁型钢组合钢管混凝土柱形式。设计了5组共10根试件的轴压试验,并开展了有限元参数分析,研究了钢管厚度、U形管外伸长度和钢材强度等参数对构件承载力和延性等力学性能的影响。结果表明:该类试件的主要破坏形态为中上部局部鼓曲破坏,适量增大U形管外伸长度可以提高承载力,但增大到一定程度之后易发生弯扭破坏;承载力和延性随着钢管厚度和钢材强度增大而增加;混凝土强度对构件的初始刚度和峰值荷载的影响都很小,但对曲线下降段的影响较大;试件端部和中部截面阴角处的混凝土应力值比各边中部更大,说明采用U形钢管与方钢管组合的方式改善了阴角处钢管对混凝土约束普遍较弱的问题。基于“统一理论”,给出了两种承载力建议计算公式,与试验结果吻合较好,两种计算方法在0.44~1.94的约束效应系数范围内具有良好的适用性。

Simulation of mould filling process using smoothed particle hydrodynamics

The implementation of high pressure die casting （HPDC） filling process modeling based on smoothed particle hydrodynamics （SPH） was discussed. A new treatment of inlet boundary was established by discriminating fluid particles from inlet particles. The roles of artificial viscosity and moving least squares method in the present model were compared in the handling pressure oscillation. The final model was substantiated by simulating filling process in HPDC in both two and three dimensions. The simulated results from SPH and finite difference method （FDM） were compared with the experiments. The results show the former is in a better agreement with experiments. It demonstrates the efficiency and precision of this SPH model in describing flow pattern in filling process.