The accumulation and release of deformation energy within the rock mass of a roadway are primary contributors to the occurrence of rock bursts.This study introduces a calculation model for the kinetic energy generated...The accumulation and release of deformation energy within the rock mass of a roadway are primary contributors to the occurrence of rock bursts.This study introduces a calculation model for the kinetic energy generated during roadway excavation,which is based on the fracture and energy states of the rock mass.The relationships among the mining depth,width of the plastic zone,rebound range of the roof and floor,stress concentration factor,and the induced kinetic energy are systematically explored.Furthermore,a rock burst risk evaluation method is proposed.The findings indicate that the energy evolution of the rock mass can be categorized into four stages:energy accumulation due to in-situ stress,energy accumulation resulting from coal compression,energy dissipation through coal plastic deformation,and energy consumption due to coal failure.The energy release from the rock mass is influenced by several factors,including mining depth,stress concentration factor,the width of the plastic zone,and the rebound range of the roof and floor.Within the plastic zone of coal,the energy released per unit volume of coal and the induced kinetic energy exhibit a nonlinear increase with mining depth and stress concentration factor,while they decrease linearly as the width of the plastic zone increases.Similarly,the driving energy per unit volume of the roof and floor shows a nonlinear increase with mining depth and stress concentration factor,a linear increase with the rebound range of the roof and floor,and a linear decrease with the width of the plastic zone.A rock burst risk evaluation method is developed based on the kinetic energy model.Field observations demonstrate that this method aligns with the drilling cuttings rock burst risk assessment method,thereby confirming its validity.展开更多
Purpose–For the commonly used concrete mix for railway tunnel linings,concrete model specimens were made,and springback and core drilling tests were conducted at different ages.The springback strength was measured to...Purpose–For the commonly used concrete mix for railway tunnel linings,concrete model specimens were made,and springback and core drilling tests were conducted at different ages.The springback strength was measured to the compressive strength of the core sample with a diameter of 100mm and a height-to-diameter ratio of 1:1.By comparing the measured strength values,the relationship between the measured values under different strength measurement methods was analyzed.Design/methodology/approach–A comparative test of the core drilling method and the rebound method was conducted on the side walls of tunnel linings in some under-construction railways to study the feasibility of the rebound method in engineering quality supervision and inspection.Findings–Tests showed that the rebound strength was positively correlated with the core drill strength.The core drill test strength was significantly higher than the rebound test strength,and the strength still increased after 56 days of age.The rebound method is suitable for the general survey of concrete strength during the construction process and is not suitable for direct supervision and inspection.Originality/value–By studying the correlation of test strength of tunnel lining concrete using two methods,the differences in test results of different methods are proposed to provide a reference for the test and evaluation of tunnel lining strength in railway engineering.展开更多
BACKGROUND Aneurysmal bone cysts(ABCs)are usually treated with curettage or various minimally invasive percutaneous procedures.Patient refractory to these treatments,as well as those with locally advanced or unresecta...BACKGROUND Aneurysmal bone cysts(ABCs)are usually treated with curettage or various minimally invasive percutaneous procedures.Patient refractory to these treatments,as well as those with locally advanced or unresectable tumors,present a challenge for orthopedic surgeons and require new treatment approaches.Antiresorptive drugs inhibit osteoclastic resorption and increase intralesional osteogenesis.Denosumab induces tumor ossification,but this effect may disappear after drug withdrawal due to limited impact on neoplastic cells.Bisphosphonates(BPs)may induce apoptosis of tumor cells and allow for long-term local control.We hypothesized that after denosumab treatment,BPs would better accumulate in the tumor and exert an irreversible antitumor effect.AIM To test the hypothesis that the sequential use of BPs after denosumab induction improves treatment outcomes in surgically unsalvageable ABCs.METHODS Using data from five electronic databases(Scopus,MEDLINE,EMBASE,PubMed,Web of Science),we aimed to identify all patients who received denosumab therapy(DT)for unresectable ABCs.Among published case reports and case series,we identified patients who discontinued denosumab for various reasons and divided them into two groups:Group 1 included 31 patients without further anti-resorptive therapy and Group 2 included 12 patients who received BPs in the context of rebound hypercalcemia.Local control rates in both groups were analyzed.RESULTS As of December 2024,43 patients have been reported in the literature who received DT for locally advanced/unresectable ABCs.There were 27 males and 16 females with a mean age of 15.8 years.At a median follow-up time of 15.5 months,there were 10 confirmed and two pathologically unconfirmed relapses after denosumab discontinuation.All 10 relapses occurred in patients in Group 1 at a median time of 13.5 months.Among patients in Group 2,with a median follow-up time of 12.5 months after completion of therapy,no local relapses were observed.The difference between local recurrence rates(32%vs 0%)is statistically significant(P value=0.02).Kaplan-Meier estimates show the same trend with marginal statistical significance(P value=0.085).Here we put forward a novel treatment algorithm.CONCLUSION BPs used in post-denosumab ossifying ABCs appear to improve treatment outcomes,presumably by targeting residual tumor cells.Prospective clinical studies are warranted to validate this promising two-stage conceptual strategy in difficult-to-treat ABC.展开更多
BACKGROUND Sustained viral load(VL)suppression is an important indicator of successful treatment among people living with human immunodeficiency virus(HIV).AIM To assess trends of different VL outcomes before and afte...BACKGROUND Sustained viral load(VL)suppression is an important indicator of successful treatment among people living with human immunodeficiency virus(HIV).AIM To assess trends of different VL outcomes before and after adoption of the Treat All policy among people living with HIV in Rwanda.METHODS Between 2014 and 2017,VL suppression[VL suppression(VLS)<200 copies/mL]was measured among people living with HIV from 28 healthcare facilities in Rwanda.Participant VL was measured at 6 months,18 months,and 30 months.The unit of analysis was visit-pair,with subjects across four visit-pair categories:(1)Sustained VL suppression(VL<200 copies/mL at two consecutive visits);(2)Persistent viremia(VL≥200 copies/mL at two consecutive visits);(3)Viral rebound(VL<200 copies/mL at prior visit only);and(4)Newly suppressed(VL<200 copies/mL at subsequent visit only).Poisson regression models with generalized estimating equations were used to estimate adjusted incidence risk ratio(aIRR)and 95%confidence intervals(CIs)for factors associated with sustained VLS.To handle missing data,multiple imputations was performed.RESULTS A total of 634 participants contributed 973 visit-pairs(295 single pairs and 339 double pairs).The median age was 37 years(interquartile range:32-43 years).The incidence rates of sustained VLS,persistent viremia,viral rebound,and new suppression were 85.2%,4.3%,4.6%,and 5.7%,respectively.Young individuals aged 18-24 years had higher incidence of viral rebound compared to those 25 years or older(14.8%vs 4.3%;P=0.011).Of the visit-pairs that had sustained VLS during the first two visits(49.8%;n=485),56.7%exhibited sustained VLS throughout follow-up.Compared to having no education,having at least primary education was associated with an increased likelihood of sustained VLS(aIRR=1.09;95%CI:1.01-1.17).Those who presented with advanced HIV disease at baseline had a 12%reduced likelihood of sustained VLS(aIRR=0.88;95%CI:0.79-0.99).Achieving sustained VLS did not differ before or after adoption of the Treat All policy.When the analysis was repeated on imputed datasets,similar results were found.CONCLUSION Although most people living with HIV have sustained VLS in Rwanda,individuals without formal education,those presenting with advanced HIV,and younger individuals were lagging on multiple outcomes.Interventions tailored to these individuals would improve treatment outcomes to achieve epidemic control.展开更多
A total of 393 potholes(368 fluvial and 25 marine potholes)were studied at seven different sites in both the fluvial and marine environments.Diverse bedrock properties and large-scale delivery of tools and grinders re...A total of 393 potholes(368 fluvial and 25 marine potholes)were studied at seven different sites in both the fluvial and marine environments.Diverse bedrock properties and large-scale delivery of tools and grinders regulate the dynamic growth,truncation,and amalgamation of potholes.Therefore,the principal objectives of the study are(i)to examine the relationship between the growth of potholes and substrate lithological with structural characteristics(applying geospatial and Schmidt hammer for rock strength analysis)and(ii)to measure the morphology,and size of tools and grinders,processes of truncation and amalgamation in hydro-geomorphic environment using various indices and field techniques.The result showed that large potholes are stretched in the direction of lineament axes and roughly parallel to the river flow direction.Here,the steady growth of pothole depth-diameter is controlled by active bedrock structures,tools,or grinders,and monsoonal high-velocity bank full discharge.Consequently,the deepening and widening of potholes are relatively slow at Bindu,Deuli,and marine beach Neil Island due to fewer structures and little supply of tools or grinders.In small stretches,(Damodar,Subarnarekha,and Rarhu)canyons and gorge-like features(bedrock incision)are formed at Rajrappa,Bhakuyadi,and Guridih sites due to cyclic truncation and amalgamation.Truncation and amalgamation processes restrict the vertical depth threshold value of potholes within 3m,particularly at Rajrappa,Bhakuyadi,and Guridih sites.Scientific study of the pothole's dynamic growth is greatly necessary for the different environmental engineering and river hydraulic projects like excavation,dredging,and dam or barrage construction.Successively,it is essential to compute the cost of rock excavation or dredging,primarily for the mechanical strength of the bedrock river channel and its stability.展开更多
Growing climate change concerns have intensified the focus on agribusiness sustainability,driving an urgent energy transition to improve production efficiency and mitigate environmental harm.The complex interplay betw...Growing climate change concerns have intensified the focus on agribusiness sustainability,driving an urgent energy transition to improve production efficiency and mitigate environmental harm.The complex interplay between energy efficiency and energy consumption highlights the essential role of strategic energy policies in ensuring sustainable development.This study used the Double-Log regression model with bootstrap resampling to examine the rebound effect in the energy transition of agribusiness focusing on five Latin American countries including Brazil,Argentina,Uruguay,Colombia,and Mexico based on the agricultural sector data during 2010–2022.The findings revealed that the rebound effect significantly influences energy transition,with varying degrees of impact across agricultural sectors.This study identified partial rebound effect across all five countries,with elasticity coefficient varying from 9.63%(Colombia’s coffee sector)to 89.12%(Brazil’s livestock sector).In Brazil’s sugarcane sector,nonrenewable energy,agricultural employment,and irrigation efficiency were identified as key factors influencing energy consumption,while in livestock sector,energy consumption was affected by CH_(4)emissions,income and well-being of farmers,water consumption,and water conservation practices.In Mexico’s livestock sector,CH_(4)emissions,nonrenewable energy,and water conservation practices were the key factors affecting energy consumption.In Argentina’s sugarcane sector,pesticides,NO_(2)emissions,renewable energy,and agricultural employment were the key factors affecting energy consumption,while renewable energy,income and well-being of farmers,and water consumption were the key factors affecting energy consumption in livestock sector.In Uruguay’s livestock sector,non-renewable energy,income and well-being of farmers,and irrigation efficiency were the key factors affecting energy consumption.In Colombia’coffee sector,NO_(2)emissions and irrigation efficiency were identified as key factors influencing energy consumption.Finally,this study reinforces the importance of aligning energy transition with Sustainable Development Goals(SDGs),ensuring that energy efficiency gains do not inadvertently increase energy consumption or environmental degradation.展开更多
The formation of abnormally low-pressure hydrocarbon reservoirs in petroliferous basins has a close relationship with tectonic uplift and the consequent erosion. In order to understand abnormally low-pressure reservoi...The formation of abnormally low-pressure hydrocarbon reservoirs in petroliferous basins has a close relationship with tectonic uplift and the consequent erosion. In order to understand abnormally low-pressure reservoirs and to provide a scientific basis for exploration and development, we established, through numerical simulation and theoretical analysis, a set of equations for the formation pressure in a closed system influenced by uplift-erosion, discussed the relationship between the genesis of abnormal pressure and uplift-erosion, and put forward the concept of balance pressure （P b ）. The results showed that abnormally high pressure coefficient may form when the current formation pressure was higher than P b , and abnormally low pressure may form when the current formation pressure was lower than P b . In the Santanghu Basin, the current formation pressure of abnormally low pressure reservoirs is lower than P b , so tectonic uplift-erosion leads to the decrease of the pressure coefficient. There is a positive correlation between the pressure drop caused by the decrease of fluid temperature and the rebound of rock porosity and strata erosion. Calculation results indicated that the reservoir pressure of Jurassic strata in the Santanghu Basin was decreased by 11.6-17.1 MPa due to tectonic uplift-erosion during the Late Yanshanian period.展开更多
A level set method of non-uniform grids is used to simulate the whole evolution of a cavitation bubble, including its growth, collapse and rebound near a rigid wall. Single-phase Navier-Stokes equation in the liquid r...A level set method of non-uniform grids is used to simulate the whole evolution of a cavitation bubble, including its growth, collapse and rebound near a rigid wall. Single-phase Navier-Stokes equation in the liquid region is solved by MAC projection algorithm combined with second-order ENO scheme for the advection terms. The moving inter-face is captured by the level set function, and the interface velocity is resolved by ＂one-side＂ velocity extension from the liquid region to the bubble region, complementing the second-order weighted least squares method across the interface and projection inside bubble. The use of non-uniform grid overcomes the difficulty caused by the large computational domain and very small bubble size. The computation is very stable without suffering from large flow-field gradients, and the results are in good agreements with other studies. The bubble interface kinematics, dynamics and its effect on the wall are highlighted, which shows that the code can effectively capture the ＂shock wave＂-like pressure and velocity at jet impact, toroidal bubble, and complicated pressure structure with peak, plateau and valley in the later stage of bubble oscillating.展开更多
AIM: To evaluate the impact of central corneal thickness(CCT) and corneal curvature on intraocular pressure(IOP) measurements performed by three different tonometers. METHODS: IOP in 132 healthy eyes of 66 participant...AIM: To evaluate the impact of central corneal thickness(CCT) and corneal curvature on intraocular pressure(IOP) measurements performed by three different tonometers. METHODS: IOP in 132 healthy eyes of 66 participants was measured using three different tonometry techniques: Goldmann applanation tonometer(GAT), Pascal dynamic contour tonometer(DCT), and ICare rebound tonometer(RT). CCT and corneal curvature were assessed. RESULTS: In healthy eyes, DCT presents significantly higher values of IOP than GAT(17.34±3.69 and 15.27±4.06 mm Hg, P<0.0001). RT measurements are significantly lower than GAT(13.56±4.33 mm Hg, P<0.0001). Compared with GAT, DCT presented on average 2.51 mm Hg higher values in eyes with CCT<600 μm and 0.99 mm Hg higher results in eyes with CCT≥600 μm. The RT results were lower on average by 1.61 and 1.95 mm Hg than those obtained by GAT, respectively. Positive correlations between CCT in eyes with CCT<600 μm were detected for all IOP measurement techniques, whereas a similar relationship was not observed in eyes with thicker corneas. A correlation between IOP values and keratometry in the group with CCT<600 μm was not detected with any of the tonometry methods. In thicker corneas, a positive correlation was found for GAT and mean keratometry values(R=0.369, P=0.005). CONCLUSION: The same method should always be chosen for routine IOP control, and measurements obtained by different methods cannot be compared. All analysed tonometry methods are dependent on CCT;thus, CCT should be taken into consideration for both diagnostics and monitoring.展开更多
The relationship between compressive strength obtained by universal testing machine and rebound value obtained by the hammer of high performance concrete was systematically investigated at the macro level. And a model...The relationship between compressive strength obtained by universal testing machine and rebound value obtained by the hammer of high performance concrete was systematically investigated at the macro level. And a model of high performance concrete strength curve was established from them. At the micro level, the microstructure, hydration products and pore structure of concrete surface were analyzed by scanning electron microscopy（SEM）, comprehensive thermal analysis（TG-DSC） and mercury intrusion porosimetry（MIP）, respectively. The effect of carbonation on surface strength was also investigated. The results showed that the concrete surface hardness layer grew rapidly at early stage and then stabilized at last with ongoing curing age; the rebound value and compressive strength of concrete with slag were higher than those of concrete with the same content of fly ash. In addition, the strength curve obtained by the least square method can satisfy the local standard requirements with an average relative error of 8.9% and a relative standard deviation of 11.3%. When the carbonation depth was 6 mm, the compressive strength calculated by national uniform strength curve was 25 PMa higher than that by high performance concrete.展开更多
The strength curves of lightweight aggregate concrete （LWAC） were tested based on detecting LWAC with density of 1 400-1 900 kg/m3 and LWAC with strength grade of LC15-LC50 by rebound method and ultrasonic-rebound c...The strength curves of lightweight aggregate concrete （LWAC） were tested based on detecting LWAC with density of 1 400-1 900 kg/m3 and LWAC with strength grade of LC15-LC50 by rebound method and ultrasonic-rebound combined method.The results show that the common measured strength curves tested by above two methods can not satisfy the required accuracy of LWAC strength test.In addition,specified compressive strength curves of testing LWAC by rebound method and ultrasonic-rebound combined method are obtained,respectively.展开更多
Particles may rebound from a substrate surface during cold spraying, which affects the quality of the coating. In this paper, the rebound phenomenon and its consequences on deposition behavior have been analyzed using...Particles may rebound from a substrate surface during cold spraying, which affects the quality of the coating. In this paper, the rebound phenomenon and its consequences on deposition behavior have been analyzed using the finite element analysis software ANSYS/LS-DYNA version 970. In a range of particle velocities of 50-1000 m/s, increases of the impact velocity caused a rapid decline of the rebound coefficient R to a low point Rmin. After that, R began to rise slowly. Then the effect of the impact velocities and material properties on the rebound phenomenon were analyzed. Both the material strength and density influenced this rebound phenomenon. Four stages of the impact process and a model of strain distribution were proposed in detail to explain the rebound phenomenon.展开更多
The production process of direct reduced iron from titanomagnetite by coal reduction in air in rotary kiln is a key step in the extraction of titanium and iron.This process is conducive to alleviating the stocking pro...The production process of direct reduced iron from titanomagnetite by coal reduction in air in rotary kiln is a key step in the extraction of titanium and iron.This process is conducive to alleviating the stocking problem of a large amount of Tibearing blast furnace slag.The relationships between particle movement and pulverized coal injection combustion in rotary kiln were studied by the particle motion simulation and the pulverized coal injection combustion simulation.In particle motion simulation,the repose angle of ore particles was calculated to be 28.06°,and the reaction zone was roughly determined by the reaction temperature isothermal surface and the repose angle;the axial discrete distribution of ore particles would further cause the axial energy fluctuation due to the endothermic nature of the reduction.In pulverized coal injection combustion simulation,the rebound effect of coal injection under gravity would cause local overheating in the rebound region due to the benefits of heat and mass transfer processes,while this could strengthen the reduction reaction of ore particles and cause agglomerate by melting.Two suggestions on weakening the energy fluctuation and agglomerate were proposed based on the characteristics of particle motion and external carbon reaction.展开更多
The tether deployment of a tethered satellite system involves the consideration of complex dynamic properties of the tether,such as large deformation,slack,and even rebound,and therefore,the dynamic modelling of the t...The tether deployment of a tethered satellite system involves the consideration of complex dynamic properties of the tether,such as large deformation,slack,and even rebound,and therefore,the dynamic modelling of the tether is necessary for performing a dynamic analysis of the system.For a variablelength tether element,the absolute nodal coordinate formulation(ANCF)in the framework of the arbitrary Lagrange-Euler(ALE)description was used to develop a precise dynamic model of a tethered satellite.The model considered the gravitational gradient force and Coriolis force in the orbital coordinate frame,and it was validated through numerical simulation.In the presence of dynamic constraints,a deployment velocity of the tether was obtained by an optimal procedure.In the simulation,rebound behavior of the tethered satellite system was observed when the ANCF-ALE model was employed.Notably,the rebound behavior cannot be predicted by the traditional dumbbell model.Furthermore,an improved optimal deployment velocity was developed.Simulation results indicated that the rebound phenomenon was eliminated,and smooth deployment as well as a stable state of the station-keeping process were achieved.Additionally,the swing amplitude in the station-keeping phase decreased when a deployment strategy based on the improved optimal deployment velocity was used.展开更多
In the process of 2-D compressional wave propagation in a rock mass with multiple parallel joints along the radian direction normal to the joints, the maximum possible wave amplitude corresponding to the points betwee...In the process of 2-D compressional wave propagation in a rock mass with multiple parallel joints along the radian direction normal to the joints, the maximum possible wave amplitude corresponding to the points between the two adjacent joints in the joint set is controlled by superposition of the multiple transmitted and the reflected waves, measured by the maximum rebound ratio. Parametric studies on the maximum rebound ratio along the radian direction normal to the joints were performed in universal distinct element code. The results show that the maximum rebound ratio is influenced by three factors, i.e., the normalized normal stiffness of joints, the ratio of joint spacing to wavelength and the joint from which the wave rebounds. The relationship between the maximum rebound ratio and the influence factors is generalized into five charts. Those charts can be used as the prediction model for estimating the maximum rebound ratio.展开更多
This paper aims to study the effect of anisotropy on strengths of several metamorphic rocks of southern(Cine) submassif of Menderes metamorphic massif in southwest Turkey. Four different metamorphic rocks including fo...This paper aims to study the effect of anisotropy on strengths of several metamorphic rocks of southern(Cine) submassif of Menderes metamorphic massif in southwest Turkey. Four different metamorphic rocks including foliated phyllite, schist, gneiss and marble(calcschist) were selected and examined.Discontinuity surveys were made along lines for each rock and evaluated with DIPS program. L-type Schmidt hammer was applied in the directions parallel and perpendicular to foliation during the field study. Several hand samples and rock blocks were collected during the field study for measurements of dry and saturated densities, dry and saturated unit weights and porosity, and for petrographic analysis and strength determination in laboratory. L-and N-type Schmidt hammers were applied in the directions perpendicular(anisotropy angle of 0°) and parallel(anisotropy angle of 90) to the foliation on selected blocks of phyllite, schist, gneiss and marble(calcschist). The phyllite and schist have higher porosity and lower density values than the other rocks. However, coarse crystalline gneiss and marble(calcschist) have higher rebound values and strengths, and they are classified as strong-very strong rocks. Generally, the rebound values in the direction perpendicular to the foliation are slightly higher than that in the direction parallel to foliation. Rebound values of N-type Schmidt hammer are higher than the L-type values except for phyllite. Sometimes, the rebound values of laboratory and field applications gave different results. This may result from variable local conditions such as minerals differentiation,discontinuities, water content, weathering degree and thickness of foliated structure.展开更多
Objective To investigate the effects of desensitization and rebound to adenosine(Ado) on action potential duration(APD) and contractility in guinea-pig atrial cells. Methods Electrical activity was recorded using stan...Objective To investigate the effects of desensitization and rebound to adenosine(Ado) on action potential duration(APD) and contractility in guinea-pig atrial cells. Methods Electrical activity was recorded using standard intracellular microelectrode technique and contractility was recorded using. We studied the effects of adenosine on the action potential and desensitization of contractility and rebound of contractility. Results The results showed that action potential duration were shortened by 1,10, 100μ mol·L -1Ado, the ratio of shortened APD was ( 9.58± 1.40)%,(13.80±2.26)%,(24.80±3.19)%, respectively. 1 μ mol·L -1Ado had no desensitization ( P >0.05), but the time of desensitization of 10μ mol·L -1 Ado and 100μ mol·L -1 Ado was 1 minute( P <0.05) and 5 minutes( P < 0.05), respectively. The desensitization of contractility of 10?μ mol·L -1 Ado was obvious in atrial cells, the decrease of contractility of 10?μ mol·L -1 Ado was obvious in atrial cells, the decrease of contractility was changed from (31.4± 16.04)%(2 minutes) to (50.60±15.87)% (4 minutes), compared with control. After washing out Ado, contractility was shown to rebound, the ratio of increase of contractility by 1,10,100 μ mol·L -1 Ado was (12.38±7.50)%,(19.00± 8.14)% and (27.60±13.44)%, respectively. Conclusion Ado can abbreviate APD in atrial cells. The desensitization of Ado on APD is characterized by concentration-dependent and time-dependent in atrial cells, and the desensitization of contractility of Ado is obvious and contractility was shown to rebound after washing out Ado.展开更多
The construction of blast furnace charge structure based on pellet and the development of short process from non-blast furnace to electric furnace will be an efficient way to accomplish"carbon peak,carbon neutral...The construction of blast furnace charge structure based on pellet and the development of short process from non-blast furnace to electric furnace will be an efficient way to accomplish"carbon peak,carbon neutral".Since drop strength is one of the most crucial quality indexes for green pellet,the crack detection in the collision process is an indispensable segment;however,the present crack determination is basically completed manually.Due to a series of problems including high labor intensity and poor detection conditions,it is urgent to develop an accurate,convenient and fast standardized method for drop strength detection.In view of the above issues,combined with plenty of experimental studies,it is found that whether rebound occurs after the collision of green ball can be used as the basis for judging if there are cracks on the surface,and the mechanism of this segment is explained by the energy conversion of collision process that the plastic deformation of the collision is a cumulative process.Each collision will cause a slight displacement of the iron ore particles;until the cumulative displacement exceeds the binding force between the particles,they will slip in a large range,that is,cracks will occur.The drop strength can be detected based on the drop-rebound mechanism determining crack generation during collision process by high-speed cameras,and the method is fully applicable to oxidized pellets with particle size of 8-16 mm though various pellet plasticities and masses increase the difficulty of bounce height monitoring.Based on the drop-rebound mechanism of green pellet,three methods for automatically detecting the drop strength are proposed,which are high-speed camera,photoelectric sensor and pressure sensor methods.展开更多
Block faults, as the -dominant tectonic framwork of western Shandong, were formed by the linked extensional fault system through two extensional movements during the Meso-Cenozoic. Both of the extensional movements ex...Block faults, as the -dominant tectonic framwork of western Shandong, were formed by the linked extensional fault system through two extensional movements during the Meso-Cenozoic. Both of the extensional movements experienced the same evloutional process: first, the upper crust was pulled apart to form faults; then the Tai-Lu-Yi (Taishan-Lushan-Yishan) fault block occurring in the footwall of the extensional fault was uplifted, which induced the shallow-level detachment movement along the early Precambrian and Palaeozoic unconformity; the ' branching' fault in the upper part of the deep-level detachment layer propagated. As the shallow detachment moved towards the north and the deep one towards the south, the Tai-Lu-Yi fault block acted as the common footwall of both the southern and northern detachment systems. The Tai-Lu-Yi fault block rebounded and uplifted as the overlying material was pulled apart to cause an unloading. Sialic material of the mid-crust below the deep detachment flowed to and accumulated in the free space below the rebounding uplifted body and thickened the body; whereas the mid-crust thinned under the graben systems. The rebounding uplifted body cooled, and then the graben system was occluded, which resulted in the crust-mantle isostatic adjustment and asthenospheric convection. As a result of the two extensional movements, the uplifted central Shandong block with the Tai-Lu-Yi area as the core stands highly above the surrounding plain characterized by graben systems. The present Mount Taishan forms the climax of the uplift.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.52374094 and 52274086)the Climbling Project of Taishan Scholar in Shandong Province(No.tspd20210313)the Shandong Provincial Youth Innovation and Technology Support Program(No.2024KJH069)。
文摘The accumulation and release of deformation energy within the rock mass of a roadway are primary contributors to the occurrence of rock bursts.This study introduces a calculation model for the kinetic energy generated during roadway excavation,which is based on the fracture and energy states of the rock mass.The relationships among the mining depth,width of the plastic zone,rebound range of the roof and floor,stress concentration factor,and the induced kinetic energy are systematically explored.Furthermore,a rock burst risk evaluation method is proposed.The findings indicate that the energy evolution of the rock mass can be categorized into four stages:energy accumulation due to in-situ stress,energy accumulation resulting from coal compression,energy dissipation through coal plastic deformation,and energy consumption due to coal failure.The energy release from the rock mass is influenced by several factors,including mining depth,stress concentration factor,the width of the plastic zone,and the rebound range of the roof and floor.Within the plastic zone of coal,the energy released per unit volume of coal and the induced kinetic energy exhibit a nonlinear increase with mining depth and stress concentration factor,while they decrease linearly as the width of the plastic zone increases.Similarly,the driving energy per unit volume of the roof and floor shows a nonlinear increase with mining depth and stress concentration factor,a linear increase with the rebound range of the roof and floor,and a linear decrease with the width of the plastic zone.A rock burst risk evaluation method is developed based on the kinetic energy model.Field observations demonstrate that this method aligns with the drilling cuttings rock burst risk assessment method,thereby confirming its validity.
文摘Purpose–For the commonly used concrete mix for railway tunnel linings,concrete model specimens were made,and springback and core drilling tests were conducted at different ages.The springback strength was measured to the compressive strength of the core sample with a diameter of 100mm and a height-to-diameter ratio of 1:1.By comparing the measured strength values,the relationship between the measured values under different strength measurement methods was analyzed.Design/methodology/approach–A comparative test of the core drilling method and the rebound method was conducted on the side walls of tunnel linings in some under-construction railways to study the feasibility of the rebound method in engineering quality supervision and inspection.Findings–Tests showed that the rebound strength was positively correlated with the core drill strength.The core drill test strength was significantly higher than the rebound test strength,and the strength still increased after 56 days of age.The rebound method is suitable for the general survey of concrete strength during the construction process and is not suitable for direct supervision and inspection.Originality/value–By studying the correlation of test strength of tunnel lining concrete using two methods,the differences in test results of different methods are proposed to provide a reference for the test and evaluation of tunnel lining strength in railway engineering.
文摘BACKGROUND Aneurysmal bone cysts(ABCs)are usually treated with curettage or various minimally invasive percutaneous procedures.Patient refractory to these treatments,as well as those with locally advanced or unresectable tumors,present a challenge for orthopedic surgeons and require new treatment approaches.Antiresorptive drugs inhibit osteoclastic resorption and increase intralesional osteogenesis.Denosumab induces tumor ossification,but this effect may disappear after drug withdrawal due to limited impact on neoplastic cells.Bisphosphonates(BPs)may induce apoptosis of tumor cells and allow for long-term local control.We hypothesized that after denosumab treatment,BPs would better accumulate in the tumor and exert an irreversible antitumor effect.AIM To test the hypothesis that the sequential use of BPs after denosumab induction improves treatment outcomes in surgically unsalvageable ABCs.METHODS Using data from five electronic databases(Scopus,MEDLINE,EMBASE,PubMed,Web of Science),we aimed to identify all patients who received denosumab therapy(DT)for unresectable ABCs.Among published case reports and case series,we identified patients who discontinued denosumab for various reasons and divided them into two groups:Group 1 included 31 patients without further anti-resorptive therapy and Group 2 included 12 patients who received BPs in the context of rebound hypercalcemia.Local control rates in both groups were analyzed.RESULTS As of December 2024,43 patients have been reported in the literature who received DT for locally advanced/unresectable ABCs.There were 27 males and 16 females with a mean age of 15.8 years.At a median follow-up time of 15.5 months,there were 10 confirmed and two pathologically unconfirmed relapses after denosumab discontinuation.All 10 relapses occurred in patients in Group 1 at a median time of 13.5 months.Among patients in Group 2,with a median follow-up time of 12.5 months after completion of therapy,no local relapses were observed.The difference between local recurrence rates(32%vs 0%)is statistically significant(P value=0.02).Kaplan-Meier estimates show the same trend with marginal statistical significance(P value=0.085).Here we put forward a novel treatment algorithm.CONCLUSION BPs used in post-denosumab ossifying ABCs appear to improve treatment outcomes,presumably by targeting residual tumor cells.Prospective clinical studies are warranted to validate this promising two-stage conceptual strategy in difficult-to-treat ABC.
文摘BACKGROUND Sustained viral load(VL)suppression is an important indicator of successful treatment among people living with human immunodeficiency virus(HIV).AIM To assess trends of different VL outcomes before and after adoption of the Treat All policy among people living with HIV in Rwanda.METHODS Between 2014 and 2017,VL suppression[VL suppression(VLS)<200 copies/mL]was measured among people living with HIV from 28 healthcare facilities in Rwanda.Participant VL was measured at 6 months,18 months,and 30 months.The unit of analysis was visit-pair,with subjects across four visit-pair categories:(1)Sustained VL suppression(VL<200 copies/mL at two consecutive visits);(2)Persistent viremia(VL≥200 copies/mL at two consecutive visits);(3)Viral rebound(VL<200 copies/mL at prior visit only);and(4)Newly suppressed(VL<200 copies/mL at subsequent visit only).Poisson regression models with generalized estimating equations were used to estimate adjusted incidence risk ratio(aIRR)and 95%confidence intervals(CIs)for factors associated with sustained VLS.To handle missing data,multiple imputations was performed.RESULTS A total of 634 participants contributed 973 visit-pairs(295 single pairs and 339 double pairs).The median age was 37 years(interquartile range:32-43 years).The incidence rates of sustained VLS,persistent viremia,viral rebound,and new suppression were 85.2%,4.3%,4.6%,and 5.7%,respectively.Young individuals aged 18-24 years had higher incidence of viral rebound compared to those 25 years or older(14.8%vs 4.3%;P=0.011).Of the visit-pairs that had sustained VLS during the first two visits(49.8%;n=485),56.7%exhibited sustained VLS throughout follow-up.Compared to having no education,having at least primary education was associated with an increased likelihood of sustained VLS(aIRR=1.09;95%CI:1.01-1.17).Those who presented with advanced HIV disease at baseline had a 12%reduced likelihood of sustained VLS(aIRR=0.88;95%CI:0.79-0.99).Achieving sustained VLS did not differ before or after adoption of the Treat All policy.When the analysis was repeated on imputed datasets,similar results were found.CONCLUSION Although most people living with HIV have sustained VLS in Rwanda,individuals without formal education,those presenting with advanced HIV,and younger individuals were lagging on multiple outcomes.Interventions tailored to these individuals would improve treatment outcomes to achieve epidemic control.
文摘A total of 393 potholes(368 fluvial and 25 marine potholes)were studied at seven different sites in both the fluvial and marine environments.Diverse bedrock properties and large-scale delivery of tools and grinders regulate the dynamic growth,truncation,and amalgamation of potholes.Therefore,the principal objectives of the study are(i)to examine the relationship between the growth of potholes and substrate lithological with structural characteristics(applying geospatial and Schmidt hammer for rock strength analysis)and(ii)to measure the morphology,and size of tools and grinders,processes of truncation and amalgamation in hydro-geomorphic environment using various indices and field techniques.The result showed that large potholes are stretched in the direction of lineament axes and roughly parallel to the river flow direction.Here,the steady growth of pothole depth-diameter is controlled by active bedrock structures,tools,or grinders,and monsoonal high-velocity bank full discharge.Consequently,the deepening and widening of potholes are relatively slow at Bindu,Deuli,and marine beach Neil Island due to fewer structures and little supply of tools or grinders.In small stretches,(Damodar,Subarnarekha,and Rarhu)canyons and gorge-like features(bedrock incision)are formed at Rajrappa,Bhakuyadi,and Guridih sites due to cyclic truncation and amalgamation.Truncation and amalgamation processes restrict the vertical depth threshold value of potholes within 3m,particularly at Rajrappa,Bhakuyadi,and Guridih sites.Scientific study of the pothole's dynamic growth is greatly necessary for the different environmental engineering and river hydraulic projects like excavation,dredging,and dam or barrage construction.Successively,it is essential to compute the cost of rock excavation or dredging,primarily for the mechanical strength of the bedrock river channel and its stability.
文摘Growing climate change concerns have intensified the focus on agribusiness sustainability,driving an urgent energy transition to improve production efficiency and mitigate environmental harm.The complex interplay between energy efficiency and energy consumption highlights the essential role of strategic energy policies in ensuring sustainable development.This study used the Double-Log regression model with bootstrap resampling to examine the rebound effect in the energy transition of agribusiness focusing on five Latin American countries including Brazil,Argentina,Uruguay,Colombia,and Mexico based on the agricultural sector data during 2010–2022.The findings revealed that the rebound effect significantly influences energy transition,with varying degrees of impact across agricultural sectors.This study identified partial rebound effect across all five countries,with elasticity coefficient varying from 9.63%(Colombia’s coffee sector)to 89.12%(Brazil’s livestock sector).In Brazil’s sugarcane sector,nonrenewable energy,agricultural employment,and irrigation efficiency were identified as key factors influencing energy consumption,while in livestock sector,energy consumption was affected by CH_(4)emissions,income and well-being of farmers,water consumption,and water conservation practices.In Mexico’s livestock sector,CH_(4)emissions,nonrenewable energy,and water conservation practices were the key factors affecting energy consumption.In Argentina’s sugarcane sector,pesticides,NO_(2)emissions,renewable energy,and agricultural employment were the key factors affecting energy consumption,while renewable energy,income and well-being of farmers,and water consumption were the key factors affecting energy consumption in livestock sector.In Uruguay’s livestock sector,non-renewable energy,income and well-being of farmers,and irrigation efficiency were the key factors affecting energy consumption.In Colombia’coffee sector,NO_(2)emissions and irrigation efficiency were identified as key factors influencing energy consumption.Finally,this study reinforces the importance of aligning energy transition with Sustainable Development Goals(SDGs),ensuring that energy efficiency gains do not inadvertently increase energy consumption or environmental degradation.
基金supported by the National Natural Science Foundation of China (No. 40802027)China "973" Project (No. 2009CB219604)the Risk Innovation Foundation of PetroChina Co. Ltd. (No. 0706d01040102)
文摘The formation of abnormally low-pressure hydrocarbon reservoirs in petroliferous basins has a close relationship with tectonic uplift and the consequent erosion. In order to understand abnormally low-pressure reservoirs and to provide a scientific basis for exploration and development, we established, through numerical simulation and theoretical analysis, a set of equations for the formation pressure in a closed system influenced by uplift-erosion, discussed the relationship between the genesis of abnormal pressure and uplift-erosion, and put forward the concept of balance pressure （P b ）. The results showed that abnormally high pressure coefficient may form when the current formation pressure was higher than P b , and abnormally low pressure may form when the current formation pressure was lower than P b . In the Santanghu Basin, the current formation pressure of abnormally low pressure reservoirs is lower than P b , so tectonic uplift-erosion leads to the decrease of the pressure coefficient. There is a positive correlation between the pressure drop caused by the decrease of fluid temperature and the rebound of rock porosity and strata erosion. Calculation results indicated that the reservoir pressure of Jurassic strata in the Santanghu Basin was decreased by 11.6-17.1 MPa due to tectonic uplift-erosion during the Late Yanshanian period.
基金the National Natural Science Foundation of China(10272032 and 10672043).
文摘A level set method of non-uniform grids is used to simulate the whole evolution of a cavitation bubble, including its growth, collapse and rebound near a rigid wall. Single-phase Navier-Stokes equation in the liquid region is solved by MAC projection algorithm combined with second-order ENO scheme for the advection terms. The moving inter-face is captured by the level set function, and the interface velocity is resolved by ＂one-side＂ velocity extension from the liquid region to the bubble region, complementing the second-order weighted least squares method across the interface and projection inside bubble. The use of non-uniform grid overcomes the difficulty caused by the large computational domain and very small bubble size. The computation is very stable without suffering from large flow-field gradients, and the results are in good agreements with other studies. The bubble interface kinematics, dynamics and its effect on the wall are highlighted, which shows that the code can effectively capture the ＂shock wave＂-like pressure and velocity at jet impact, toroidal bubble, and complicated pressure structure with peak, plateau and valley in the later stage of bubble oscillating.
文摘AIM: To evaluate the impact of central corneal thickness(CCT) and corneal curvature on intraocular pressure(IOP) measurements performed by three different tonometers. METHODS: IOP in 132 healthy eyes of 66 participants was measured using three different tonometry techniques: Goldmann applanation tonometer(GAT), Pascal dynamic contour tonometer(DCT), and ICare rebound tonometer(RT). CCT and corneal curvature were assessed. RESULTS: In healthy eyes, DCT presents significantly higher values of IOP than GAT(17.34±3.69 and 15.27±4.06 mm Hg, P<0.0001). RT measurements are significantly lower than GAT(13.56±4.33 mm Hg, P<0.0001). Compared with GAT, DCT presented on average 2.51 mm Hg higher values in eyes with CCT<600 μm and 0.99 mm Hg higher results in eyes with CCT≥600 μm. The RT results were lower on average by 1.61 and 1.95 mm Hg than those obtained by GAT, respectively. Positive correlations between CCT in eyes with CCT<600 μm were detected for all IOP measurement techniques, whereas a similar relationship was not observed in eyes with thicker corneas. A correlation between IOP values and keratometry in the group with CCT<600 μm was not detected with any of the tonometry methods. In thicker corneas, a positive correlation was found for GAT and mean keratometry values(R=0.369, P=0.005). CONCLUSION: The same method should always be chosen for routine IOP control, and measurements obtained by different methods cannot be compared. All analysed tonometry methods are dependent on CCT;thus, CCT should be taken into consideration for both diagnostics and monitoring.
基金Funded by the National Natural Science Foundation of China(No.2015CB655102)National Science&Technology Pillar Program(No.2014BAB15B01-02)
文摘The relationship between compressive strength obtained by universal testing machine and rebound value obtained by the hammer of high performance concrete was systematically investigated at the macro level. And a model of high performance concrete strength curve was established from them. At the micro level, the microstructure, hydration products and pore structure of concrete surface were analyzed by scanning electron microscopy（SEM）, comprehensive thermal analysis（TG-DSC） and mercury intrusion porosimetry（MIP）, respectively. The effect of carbonation on surface strength was also investigated. The results showed that the concrete surface hardness layer grew rapidly at early stage and then stabilized at last with ongoing curing age; the rebound value and compressive strength of concrete with slag were higher than those of concrete with the same content of fly ash. In addition, the strength curve obtained by the least square method can satisfy the local standard requirements with an average relative error of 8.9% and a relative standard deviation of 11.3%. When the carbonation depth was 6 mm, the compressive strength calculated by national uniform strength curve was 25 PMa higher than that by high performance concrete.
文摘The strength curves of lightweight aggregate concrete （LWAC） were tested based on detecting LWAC with density of 1 400-1 900 kg/m3 and LWAC with strength grade of LC15-LC50 by rebound method and ultrasonic-rebound combined method.The results show that the common measured strength curves tested by above two methods can not satisfy the required accuracy of LWAC strength test.In addition,specified compressive strength curves of testing LWAC by rebound method and ultrasonic-rebound combined method are obtained,respectively.
基金supported by the National Natural Science Foundation of China (Nos.50871019 and 50874009)
文摘Particles may rebound from a substrate surface during cold spraying, which affects the quality of the coating. In this paper, the rebound phenomenon and its consequences on deposition behavior have been analyzed using the finite element analysis software ANSYS/LS-DYNA version 970. In a range of particle velocities of 50-1000 m/s, increases of the impact velocity caused a rapid decline of the rebound coefficient R to a low point Rmin. After that, R began to rise slowly. Then the effect of the impact velocities and material properties on the rebound phenomenon were analyzed. Both the material strength and density influenced this rebound phenomenon. Four stages of the impact process and a model of strain distribution were proposed in detail to explain the rebound phenomenon.
基金This work was supported by the National Key R&D Program of China(2018YFC1900500)National Natural Science Foundation of China(No.51961020).
文摘The production process of direct reduced iron from titanomagnetite by coal reduction in air in rotary kiln is a key step in the extraction of titanium and iron.This process is conducive to alleviating the stocking problem of a large amount of Tibearing blast furnace slag.The relationships between particle movement and pulverized coal injection combustion in rotary kiln were studied by the particle motion simulation and the pulverized coal injection combustion simulation.In particle motion simulation,the repose angle of ore particles was calculated to be 28.06°,and the reaction zone was roughly determined by the reaction temperature isothermal surface and the repose angle;the axial discrete distribution of ore particles would further cause the axial energy fluctuation due to the endothermic nature of the reduction.In pulverized coal injection combustion simulation,the rebound effect of coal injection under gravity would cause local overheating in the rebound region due to the benefits of heat and mass transfer processes,while this could strengthen the reduction reaction of ore particles and cause agglomerate by melting.Two suggestions on weakening the energy fluctuation and agglomerate were proposed based on the characteristics of particle motion and external carbon reaction.
基金supported by the Natural Science Foundation of Shaanxi Province,China(2020JQ-288)Science and Technology on Space Intelligent Control Laboratory,China(HTKJ2019KL502016)+1 种基金China Scholarship Council(201806120093)National Natural Science Foundation of China(61903289).
文摘The tether deployment of a tethered satellite system involves the consideration of complex dynamic properties of the tether,such as large deformation,slack,and even rebound,and therefore,the dynamic modelling of the tether is necessary for performing a dynamic analysis of the system.For a variablelength tether element,the absolute nodal coordinate formulation(ANCF)in the framework of the arbitrary Lagrange-Euler(ALE)description was used to develop a precise dynamic model of a tethered satellite.The model considered the gravitational gradient force and Coriolis force in the orbital coordinate frame,and it was validated through numerical simulation.In the presence of dynamic constraints,a deployment velocity of the tether was obtained by an optimal procedure.In the simulation,rebound behavior of the tethered satellite system was observed when the ANCF-ALE model was employed.Notably,the rebound behavior cannot be predicted by the traditional dumbbell model.Furthermore,an improved optimal deployment velocity was developed.Simulation results indicated that the rebound phenomenon was eliminated,and smooth deployment as well as a stable state of the station-keeping process were achieved.Additionally,the swing amplitude in the station-keeping phase decreased when a deployment strategy based on the improved optimal deployment velocity was used.
基金Projects(50278057) supported by the National Natural Science Foundation of China project(2002CB412703) supported by Major State Basic Research Development Program of China
文摘In the process of 2-D compressional wave propagation in a rock mass with multiple parallel joints along the radian direction normal to the joints, the maximum possible wave amplitude corresponding to the points between the two adjacent joints in the joint set is controlled by superposition of the multiple transmitted and the reflected waves, measured by the maximum rebound ratio. Parametric studies on the maximum rebound ratio along the radian direction normal to the joints were performed in universal distinct element code. The results show that the maximum rebound ratio is influenced by three factors, i.e., the normalized normal stiffness of joints, the ratio of joint spacing to wavelength and the joint from which the wave rebounds. The relationship between the maximum rebound ratio and the influence factors is generalized into five charts. Those charts can be used as the prediction model for estimating the maximum rebound ratio.
文摘This paper aims to study the effect of anisotropy on strengths of several metamorphic rocks of southern(Cine) submassif of Menderes metamorphic massif in southwest Turkey. Four different metamorphic rocks including foliated phyllite, schist, gneiss and marble(calcschist) were selected and examined.Discontinuity surveys were made along lines for each rock and evaluated with DIPS program. L-type Schmidt hammer was applied in the directions parallel and perpendicular to foliation during the field study. Several hand samples and rock blocks were collected during the field study for measurements of dry and saturated densities, dry and saturated unit weights and porosity, and for petrographic analysis and strength determination in laboratory. L-and N-type Schmidt hammers were applied in the directions perpendicular(anisotropy angle of 0°) and parallel(anisotropy angle of 90) to the foliation on selected blocks of phyllite, schist, gneiss and marble(calcschist). The phyllite and schist have higher porosity and lower density values than the other rocks. However, coarse crystalline gneiss and marble(calcschist) have higher rebound values and strengths, and they are classified as strong-very strong rocks. Generally, the rebound values in the direction perpendicular to the foliation are slightly higher than that in the direction parallel to foliation. Rebound values of N-type Schmidt hammer are higher than the L-type values except for phyllite. Sometimes, the rebound values of laboratory and field applications gave different results. This may result from variable local conditions such as minerals differentiation,discontinuities, water content, weathering degree and thickness of foliated structure.
基金ThisresearchwassupportedbytheNationalNaturalScienceFoundationofChina (No .30 2 70 5 5 4No .39970 2 73) +1 种基金Doctonialsubject (No .2 0 0 10 6 980 34)keyItemofScientificTechnologyforministryofEducation (No .0 116 1) .
文摘Objective To investigate the effects of desensitization and rebound to adenosine(Ado) on action potential duration(APD) and contractility in guinea-pig atrial cells. Methods Electrical activity was recorded using standard intracellular microelectrode technique and contractility was recorded using. We studied the effects of adenosine on the action potential and desensitization of contractility and rebound of contractility. Results The results showed that action potential duration were shortened by 1,10, 100μ mol·L -1Ado, the ratio of shortened APD was ( 9.58± 1.40)%,(13.80±2.26)%,(24.80±3.19)%, respectively. 1 μ mol·L -1Ado had no desensitization ( P >0.05), but the time of desensitization of 10μ mol·L -1 Ado and 100μ mol·L -1 Ado was 1 minute( P <0.05) and 5 minutes( P < 0.05), respectively. The desensitization of contractility of 10?μ mol·L -1 Ado was obvious in atrial cells, the decrease of contractility of 10?μ mol·L -1 Ado was obvious in atrial cells, the decrease of contractility was changed from (31.4± 16.04)%(2 minutes) to (50.60±15.87)% (4 minutes), compared with control. After washing out Ado, contractility was shown to rebound, the ratio of increase of contractility by 1,10,100 μ mol·L -1 Ado was (12.38±7.50)%,(19.00± 8.14)% and (27.60±13.44)%, respectively. Conclusion Ado can abbreviate APD in atrial cells. The desensitization of Ado on APD is characterized by concentration-dependent and time-dependent in atrial cells, and the desensitization of contractility of Ado is obvious and contractility was shown to rebound after washing out Ado.
基金support from the Excellent Youth Foundation of Anhui Scientific Committee(2208085J19).
文摘The construction of blast furnace charge structure based on pellet and the development of short process from non-blast furnace to electric furnace will be an efficient way to accomplish"carbon peak,carbon neutral".Since drop strength is one of the most crucial quality indexes for green pellet,the crack detection in the collision process is an indispensable segment;however,the present crack determination is basically completed manually.Due to a series of problems including high labor intensity and poor detection conditions,it is urgent to develop an accurate,convenient and fast standardized method for drop strength detection.In view of the above issues,combined with plenty of experimental studies,it is found that whether rebound occurs after the collision of green ball can be used as the basis for judging if there are cracks on the surface,and the mechanism of this segment is explained by the energy conversion of collision process that the plastic deformation of the collision is a cumulative process.Each collision will cause a slight displacement of the iron ore particles;until the cumulative displacement exceeds the binding force between the particles,they will slip in a large range,that is,cracks will occur.The drop strength can be detected based on the drop-rebound mechanism determining crack generation during collision process by high-speed cameras,and the method is fully applicable to oxidized pellets with particle size of 8-16 mm though various pellet plasticities and masses increase the difficulty of bounce height monitoring.Based on the drop-rebound mechanism of green pellet,three methods for automatically detecting the drop strength are proposed,which are high-speed camera,photoelectric sensor and pressure sensor methods.
文摘Block faults, as the -dominant tectonic framwork of western Shandong, were formed by the linked extensional fault system through two extensional movements during the Meso-Cenozoic. Both of the extensional movements experienced the same evloutional process: first, the upper crust was pulled apart to form faults; then the Tai-Lu-Yi (Taishan-Lushan-Yishan) fault block occurring in the footwall of the extensional fault was uplifted, which induced the shallow-level detachment movement along the early Precambrian and Palaeozoic unconformity; the ' branching' fault in the upper part of the deep-level detachment layer propagated. As the shallow detachment moved towards the north and the deep one towards the south, the Tai-Lu-Yi fault block acted as the common footwall of both the southern and northern detachment systems. The Tai-Lu-Yi fault block rebounded and uplifted as the overlying material was pulled apart to cause an unloading. Sialic material of the mid-crust below the deep detachment flowed to and accumulated in the free space below the rebounding uplifted body and thickened the body; whereas the mid-crust thinned under the graben systems. The rebounding uplifted body cooled, and then the graben system was occluded, which resulted in the crust-mantle isostatic adjustment and asthenospheric convection. As a result of the two extensional movements, the uplifted central Shandong block with the Tai-Lu-Yi area as the core stands highly above the surrounding plain characterized by graben systems. The present Mount Taishan forms the climax of the uplift.
