In geotechnical engineering applications,including mining and tunnel construction,the stability of fractured rock masses is paramount to ensuring structural safety.The spatial distribution and temporal evolution of in...In geotechnical engineering applications,including mining and tunnel construction,the stability of fractured rock masses is paramount to ensuring structural safety.The spatial distribution and temporal evolution of internal fractures fundamentally govern the mechanical behavior and failure mechanisms of rock masses.Nevertheless,the inherent complexity and structural concealment of rock mass systems pose significant challenges for the direct measurement of critical internal mechanical parameters.This study explores the use of deep learning to invert mechanical responses of NPR(Negative Poisson's Ratio)anchored fractured rock masses.Discrete Element Method(DEM)simulations were conducted to generate datasets including stress-strain curves and crack numbers under various initial fracture distributions.Three models—GRU,CNN+GRU,and CNN+GRU+ATT—were developed to predict rock mechanical parameters from NPR cable force data.Results show that the CNN+GRU+ATT model achieves superior accuracy,with R^(2)>0.90 and RMSE<5 on stress prediction tasks.It also accurately estimates initial crack quantity(np),with mean prediction error under 10%for high-fracture scenarios.The proposed model effectively captures stress fluctuations,offering early-warning potential for failure.The approach demonstrates strong generalization and robustness across varying crack configurations,providing a feasible framework for real-time health monitoring and mechanical parameter estimation in fractured rock engineering.展开更多
Weak structural planes commonly exist in underground engineering.These planes make anchor structures more prone to failure,threatening rock stability,threatening the safety and stability of underground engineering.Opt...Weak structural planes commonly exist in underground engineering.These planes make anchor structures more prone to failure,threatening rock stability,threatening the safety and stability of underground engineering.Optical-Thermal-Acoustic(OTA)monitoring was applied during uniaxial compression tests on cross-layer anchored rock masses.The study revealed the mechanical properties,failure characteristics,and energy evolution of rock masses with different anchoring methods and bedding angles.Key findings:anchoring suppresses transverse deformation and tensile crack propagation,increasing elastic modulus and bearing capacity;anchored rock shows more intense acoustic emission but smaller infrared temperature changes;the structural plane angle controls the direction of crack extension and the evolution of the strain characteristics,and the rock is prone to instantaneous slip failure of the structural surface at 45°–75°,and the lower strength with significant IR change characteristics.Distinct OTA characteristics during rupture validate the method's reliability for rockburst early warning and intensity assessment.Moreover,based on the failure characteristics of cross-layer anchored rock masses,a shear failure criterion for anchored structural planes is established.This criterion enables prediction of rock mass failure modes,analysis of bolt support resistance,reference for support design/construction in underground engineering within complex strata.展开更多
The increasingly serious electromagnetic(EM)radiation and related pollution effects have gradually attracted people's attention in the information age.Hence,it's crucial to develop adaptive shielding materials...The increasingly serious electromagnetic(EM)radiation and related pollution effects have gradually attracted people's attention in the information age.Hence,it's crucial to develop adaptive shielding materials with minimum EM waves(EMW)reflection.In this paper,Ag nanoparticles loaded mesoporous carbon hollow spheres(MCHS@Ag)were synthesized by chemical reduction method,and cellulose nanofibers(CNF)/MXene/MCHS@Ag homogeneous composites were prepared.The total EM interference shielding efficiency(SET)of CNF/MXene/MCHS@Ag composite film was 32.83 dB(at 12.4 GHz),and the absorption effectiveness(SEA)was improved to 26.6 dB,which was 63.1%and 195.5%higher than that of CNF/MXene/MCHS composite film.The low dielectric property of MCHS effectively optimized the impedance matching between the composites and air.The hollow porous structure prolonged the transmission path of EMW and increased the absorption loss of the composites.At the same time,Ag nanoparticles located the MCHS were helpful to construct the internal conductive path overcoming the damage of the conductive property caused by the low dielectric of MCHS.This research adopts a straightforward method to construct a lightweight,pliable,and mesoporous composites for EMI shielding,which serves a crucial role in the current era of severe EM pollution.展开更多
With resource exploitation and engineering construction gradually going deeper,the surrounding rock dynamic disaster becomes frequent and violent.The anchorage support is a common control method of surrounding rock in...With resource exploitation and engineering construction gradually going deeper,the surrounding rock dynamic disaster becomes frequent and violent.The anchorage support is a common control method of surrounding rock in underground engineering.To study the dynamic damage characteristics of anchored rock and the energy absorption control mechanism of dynamic disasters,a new type of constant resistance and energy absorption(CREA)material with high strength,high elongation and high energy absorption characteristics is developed.A contrast test of rockbursts in anchored rock with different support materials is conducted.The test results show that the surface damage rates and energy release degree of anchored rock with common bolt(CB)and CREA are lower than those of unanchored rock,respectively.The total energy,average energy and maximum energy released by CREA anchored rock are 30.9%,94.3%and 84.4%lower than those of CB anchored rock.Compared with unanchored rock,the rockburst peak stress in the CREA anchored rock is increased by 39.9%,and the rockburst time is delayed by 53.2%.Based on the rockburst energy calculation model,the evolution law of rockburst peak stress and energy release is investigated.The control mechanism of CREA support units on rock dynamic failure is clarified.展开更多
In this paper is presented a concept solution and acceptance test application procedure of deep pit protection structure,intended for three underground levels of residential building:A,B,C,D,block 10C,Budva,Montenegro...In this paper is presented a concept solution and acceptance test application procedure of deep pit protection structure,intended for three underground levels of residential building:A,B,C,D,block 10C,Budva,Montenegro.The anchored wall used consist of nongravity cantilevered walls with three levels of ground anchors.Nongravity cantilevered walls employ continuous walls constructed in slurry trenches(i.e.,slurry(diaphragm)walls),e.g vertical elements that are drilled to depths below the finished excavation grade.For those nongravity cantilevered walls,support is provided through the shear and bending stiffness of the vertical wall elements and passive resistance from the soil below the finished excavation grade.Anchored wall support relies on these components as well as lateral resistance provided by the ground anchors to resist horizontal pressures(e.g.,earth,water,external loads)acting on the wall.Anchored wall analysed and applied is temporary supporting structure necessary for the excavation and erection of the underground structure part up to ground surface level.Temporary ground anchors lifetime is up to two years.Dynamic loads are not considered.展开更多
Rockburst is a common disaster in deep underground engineering,which seriously impacts project construction safety.Understanding its causes and burst resistance mechanism is of significance for rockburst prevention an...Rockburst is a common disaster in deep underground engineering,which seriously impacts project construction safety.Understanding its causes and burst resistance mechanism is of significance for rockburst prevention and mitigation.We developed a new type of high strength,large elongation,and strong energy-absorbing material,and conducted comparative tests on both basic and anchored rock specimens with such material.We analyzed the rockburst process,energy release and peak stress of the rock,and force and deformation withstood by the energy-absorbing bolts.The experimental results show that the energy reduction rate of the rocks reinforced by energy-absorbing bolts is more than 80%,compared with that of the basic rock.The force exerted on the energy-absorbing bolts increases suddenly when the rockburst occurs,and the strength utilization rates of the energy-absorbing bolts under strain rockburst and impact rockburst conditions are 73.3%and 61.2%,respectively.Rockburst also causes non-uniform shear deformation of the anchor bolt.Based on the rockburst energy criterion,the peak stress of the anchored rock is 2.2 times and 2.5 times the uniaxial compressive strength of the rock,respectively,under strain rockburst and impact rockburst conditions.The energy required for rockburst is 396.0 and 478.4 kJ/m^(3),respectively.The energy-anchoring bolts can effectively reduce the likelihood of rockburst.The results can provide a reference for support design for burst-prone rock in underground engineering.展开更多
A new capillary gas chromatography stationary phase, monokis (2,6 di O benzyl 3 O propyl (3’)) hexakis(2,6 di O benzyl 3 O methyl) β CD bonded polysiloxane, was synthesized. It ex...A new capillary gas chromatography stationary phase, monokis (2,6 di O benzyl 3 O propyl (3’)) hexakis(2,6 di O benzyl 3 O methyl) β CD bonded polysiloxane, was synthesized. It exhibited separation abilities to disubstituted benzene isomers and some chiral solutes. It was also found that the polarity of CD derivatives can be lowered both by chemically bonding it to polysiloxane and by diluting it in polysiloxane. The separation abilities of the polysiloxane anchored CDs (SP CD) are higher than that of the unbonded CDs (S CD) and the diluted S CD at lower column temperature. Hydrosilylation reaction is one of the best methods to lower the operating temperature of CDs.展开更多
The development of high-performance metal nanocluster catalysts is hindered by a fundamental stabilization-activity trade-off.Oxide supports often induce over-stabilization via insulating overlayers that block active ...The development of high-performance metal nanocluster catalysts is hindered by a fundamental stabilization-activity trade-off.Oxide supports often induce over-stabilization via insulating overlayers that block active sites,while conventional functionalized carbon supports suffer from thermodynamic instability and weak metal-support electronic coupling,leading to aggregation.Herein,a novel defectmediated covalent anchoring strategy is presented to immobilize transition metal(Pd,Ru,and Ir)NCs within ordered mesoporous carbon.This approach leverages intrinsic micropore defects to capture precursors and facilitate in-situ formation of direct metal-carbon covalent bonds.Controlled pyrolysis confines metal atom sintering into clusters within the mesopores,achieving high metal loading.This enrooted architectu re uniquely balances stability and activity:it avoids the excessive metal-carbon bonding detrimental to single-atom catalysts while maintaining sufficient,controllable interactions.The resulting Pd NCs catalyst exhibits exceptional hydrogen oxidation reaction activity,surpassing mass activity benchmarks of conventional Pt/C.Critically,this methodology decouples atomic-scale stabilization from catalytic site accessibility,resolving the long-standing activity-stability dilemma and providing a generalizable platform for fabricating stable,high-loading cluster catalysts with optimized electronic structures.展开更多
AIM To design a miniature magnetically anchored and controlled camera system to reduce the number of trocars which are required for laparoscopy.METHODS The system consists of a miniature magnetically anchored camera w...AIM To design a miniature magnetically anchored and controlled camera system to reduce the number of trocars which are required for laparoscopy.METHODS The system consists of a miniature magnetically anchored camera with a 30° downward angle, an external magnetically anchored unit, and a vision output device. The camera weighs 12 g, measures Φ10.5 mm × 55 mm and has two magnets, a vision model, a light source, and a metal hexagonal nut. To test the prototype, the camera was inserted through a 12-mm conventional trocar in an ex vivo real liver laparoscopic training system. A trocar-less laparoscopic cholecystectomy was performed 6 times using a 12-mm and a 5-mm conventional trocar. In addition, the same procedure was performed in four canine models.RESULTS Both procedures were successfully performed using only two conventional laparoscopic trocars. The cholecystectomy was completed without any major complication in 42 min(38-45 min) in vitro and in 50 min(45-53 min) using an animal model. This camera was anchored and controlled by an external unit magnetically anchored on the abdominal wall. The camera could generate excellent image. with no instrument collisions.CONCLUSION The camera system we designed provides excellent optics and can be easily maneuvered. The number of conventional trocars is reduced without adding technical difficulties.展开更多
This study compares the strength characteristics of rocks anchored by NPR bolts and ordinary bolts with varied preloads,based on the mechanical properties of NPR bolts(with a negative Poisson’s ratio).The results sho...This study compares the strength characteristics of rocks anchored by NPR bolts and ordinary bolts with varied preloads,based on the mechanical properties of NPR bolts(with a negative Poisson’s ratio).The results show that the uniaxial compressive stress-strain curve of ordinary anchored rocks exhibits noticeable abrupt changes.After reaching peak strength,the bolt breaks,whereas the stress-strain curve of NPR-anchored rocks is smoother.The NPR bolt enters the stage of continuous resistance after reaching maximal strength and does not break.As the preload increases,the strength of the anchored rock grows linearly.A calculation equation for the strength of the anchored rock is proposed based on the preload.The theoretical equation fits the test results well,and the fitted parameters show that NPR bolts can better increase the strength of the rock.The concept of dynamic toughness UC of anchored rock is proposed to reflect the comprehensive mechanical properties of anchored rock,including strength and plasticity.As the preload increases,the UC of ordinary anchored rock first decreases and then increases,while the UC of the NPR anchored rock does not change significantly with the preload when the strain is small,and the UC increases with the increase of the preload when the strain is large.展开更多
Rock-embedded foundations with good uplift and bearing capacity are often used in mountains or hilly areas.However,there are soil layers with a certain thickness on the rocks in these mountainous areas,and the utiliza...Rock-embedded foundations with good uplift and bearing capacity are often used in mountains or hilly areas.However,there are soil layers with a certain thickness on the rocks in these mountainous areas,and the utilization of those soil layers is a problem worthy of attention in foundation construction.Considering construction-and cost-related factors,traditional single-form foundations built on such sites often cannot provide sufficient resistance against uplift.Therefore,an anchored pier foundation composed of anchors and belled piers,specifically constructed for such conditions,can be invaluable in practice.This paper introduces an experimental and analytical study to investigate the uplift capacity and the uplift mobilization coefficients(UMCs)of the anchored pier foundation.In this study,three in-situ monotonic pullout tests were carried out to analyze the load–displacement characteristics,axial force distribution,load transfer mechanism,and failure mechanism.A hyperbolic model is used to fit the load–displacement curves and to reveal the asynchrony of the ultimate limit states(ULSs)of the anchor group and the belled pier.Based on the results,the uplift capacity can be calculated by the UMCs and the anchor group and pier uplift capacities.Finally,combined with the estimation of the deformation modulus of the soil and rock,the verification calculation of the uplift capacity and UMC was carried out on the test results from different anchored pier foundations.展开更多
To improve the accuracy of illumination estimation while maintaining a relative fast execution speed, a novel learning-based color constancy using color edge moments and regularized regression in an anchored neighborh...To improve the accuracy of illumination estimation while maintaining a relative fast execution speed, a novel learning-based color constancy using color edge moments and regularized regression in an anchored neighborhood is proposed. First, scene images are represented by the color edge moments of various orders. Then, an iterative regression with a squared Frobenius norm（F-norm） regularizer is introduced to learn the mapping between the edge moments and illuminants in the neighborhood of the anchored sample.Illumination estimation for the test image finally becomes the nearest anchored point search followed by a matrix multiplication using the associated mapping matrix which can be precalculated and stored. Experiments on two standard image datasets show that the proposed approach significantly outperforms the state-of-the-art algorithms with a performance increase of at least 10. 35% and 7. 44% with regard to median angular error.展开更多
The thinking of co evolution is applied to the optimization of retaining and protecting structure for deep foundation excavation, and the system of optimization of anchored row piles for deep foundation pit has been a...The thinking of co evolution is applied to the optimization of retaining and protecting structure for deep foundation excavation, and the system of optimization of anchored row piles for deep foundation pit has been already developed successfully. For the co evolution algorithm providing an evolutionary mechanism to simulate ever changing problem space, it is an optimization algorithm that has high performance, especially applying to the optimization of complicated system of retaining and protecting for deep foundation pit. It is shown by many engineering practices that the co evolution algorithm has obvious optimization effect, so it can be an important method of optimization of retaining and protecting for deep foundation pit. Here the authors discuss the co evolution model, object function, all kinds of constraint conditions and their disposal methods, and several key techniques of system realization.展开更多
Both aliphatic and aromatic ketones are efficiently transfer-hydrogenated by propan-2-ol under mild conditions in the presence of a catalytic amount of poly(2,6-dimethyl-1,4-Phenylene oxide) (PPO) anchored ruthenium...Both aliphatic and aromatic ketones are efficiently transfer-hydrogenated by propan-2-ol under mild conditions in the presence of a catalytic amount of poly(2,6-dimethyl-1,4-Phenylene oxide) (PPO) anchored ruthenium complex and sodium hydroxide. An important feature of this polymer anchored catalyst is its stability in air.展开更多
Fishing boats are usually anchored side by side in the harbor because of the small structural size and poor resistance to wind and waves.A series of physical model experiments are conducted to investigate the motion c...Fishing boats are usually anchored side by side in the harbor because of the small structural size and poor resistance to wind and waves.A series of physical model experiments are conducted to investigate the motion characteristics of multiple fishing boats that are moored together.A decay test in calm water is conducted to study the natural period and damping coefficients.Regular wave experiments are performed to analyze the roll motion response of each boat for four modes(different numbers of boats side-by-side).The results indicate that the“natural period”of each boat for the mode of multi-boats especially three or four boats,is slightly smaller than that of a single boat,whereas the damping coefficient is visibly larger than that of a single boat.The maximum roll angle of each boat does not appear at the same time under a 90°incident wave.Small roll motion energy is generated at low frequencies and high frequencies when multiple boats are moored together.The energy decreases with the increasing wave period.The roll motion responses of each boat in four modes exhibit different trends with the increasing wave frequency.The number of boats and boat position have significant effects on roll motion.展开更多
Oxygen reduction reaction(ORR)is the key reaction at the cathode of proton exchange membrane fuel cells(PEMFCs)and metal-air batteries(1)To address the challenges associated with Pt-based electrocatalysts having promi...Oxygen reduction reaction(ORR)is the key reaction at the cathode of proton exchange membrane fuel cells(PEMFCs)and metal-air batteries(1)To address the challenges associated with Pt-based electrocatalysts having prominent activity for ORR,e.g.scarce abundance,prohibitive cost,poor stability,and vulnerability to reaction intermediates,it is necessary to explore other cost-effective ORR electrocatalysts with competitive or even superior performance to promote the commercialization of the energy conversion devices.展开更多
Lithium (Li)-CO_(2) battery is rising as an attractive energy-storage system with the competence of CO_(2) conversion/fixation. However, its practical development is seriously hindered by the high overpotential. Herei...Lithium (Li)-CO_(2) battery is rising as an attractive energy-storage system with the competence of CO_(2) conversion/fixation. However, its practical development is seriously hindered by the high overpotential. Herein, a rational design on a highly catalytic Li-CO_(2) battery electrode built by graphdiyne powder as a multi-functional laminar scaffold with anchored highly dispersed Ru nanoparticles is explored. The strong interaction between the abundant acetylenic bond sites of graphdiyne scaffold and Ru nanoparticles can effectively promote the electrochemical progress and reduce the voltage polarization. The unique channels architecture of the cathodic catalyst with enough space not only accelerates CO_(2) diffusion and electrons/Li+ transport, but also allows a large amount of accommodation for discharged product (Li2CO3) to assure an advanced capacity. The corresponding Li-CO_(2) battery displays an advanced discharged capacity of 15,030 mAh/g at 500 mA/g, great capacity retention of 8873 mAh/g at 2 A/g, high coulombic efficiency of 97.6% at 500 mA/g and superior life span for 120 cycles with voltage gap of 1.67 V under a restricted capacity of 1000 mAh/g at 500 mA/g. Ex/in-situ studies prove that synergy between Ru nanoparticles and acetylene bonds of GDY can boost the round-trip CO_(2)RR and CO_(2)ER kinetics.展开更多
The deep mining of coal resources is accompanied by severe environmental challenges and various potential engineering hazards.The implementation of NPR(negative Poisson's ratio)bolts are capable of controlling lar...The deep mining of coal resources is accompanied by severe environmental challenges and various potential engineering hazards.The implementation of NPR(negative Poisson's ratio)bolts are capable of controlling large deformations in the surrounding rock effectively.This paper focuses on studying the mechanical properties of the NPR bolt under static disturbance load.The deep nonlinear mechanical experimental system was used to study the mechanical behavior of rock samples with different anchored types(unanchored/PR anchored/2G NPR anchored)under static disturbance load.The whole process of rock samples was taken by high-speed camera to obtain the real-time failure characteristics under static disturbance load.At the same time,the acoustic emission signal was collected to obtain the key characteristic parameters of acoustic emission such as acoustic emission count,energy,and frequency.The deformation at the failure of the samples was calculated and analyzed by digital speckle software.The findings indicate that the failure mode of rock is influenced by different types of anchoring.The peak failure strength of 2G NPR bolt anchored rock samples exhibits an increase of 6.5%when compared to the unanchored rock samples.The cumulative count and cumulative energy of acoustic emission exhibit a decrease of 62.16%and 62.90%,respectively.The maximum deformation of bearing capacity exhibits an increase of 59.27%,while the failure time demonstrates a delay of 42.86%.The peak failure strength of the 2G NPR bolt anchored ones under static disturbance load exhibits an increase of 5.94%when compared to the rock anchored by PR(Poisson's ratio)bolt.The cumulative count and cumulative energy of acoustic emission exhibit a decrease of 47.16%and 43.86%,respectively.The maximum deformation of the bearing capacity exhibits an increase of 50.43%,and the failure time demonstrates a delay of 32%.After anchoring by 2G NPR bolt,anchoring support effectively reduces the risk of damage caused by static disturbance load.These results demonstrate that the support effect of 2G NPR bolt materials surpasses that of PR bolt.展开更多
Although progress in face recognition is encouraging, the accuracy rate of face recognition remains to be increased. Since the face image quality has a positive influence on face recognition accuracy, the image enhanc...Although progress in face recognition is encouraging, the accuracy rate of face recognition remains to be increased. Since the face image quality has a positive influence on face recognition accuracy, the image enhancement methods are popular in face recognition. Most current image enhancement methods aim at improving visual appearance, but cannot improve recognition accuracy remarkably. In this paper, a feature evaluation operator is designed to overcome this problem. The operator selects patches with the best quality, and then face image is reconstructed with the selected patches. The proposed algorithm is tested on two different face recognition applications. Accuracy is raised after enhancement, and the result proves that the proposed algorithm is effective.展开更多
Carbonylation of allyl halides catalyzed by poly(N-vinyl-2-pyrro- lidone) anchored palladium catalyst affords β,r-butonic acid under atmo- spheric pressure and at room temperature.The activity and efficiency of the c...Carbonylation of allyl halides catalyzed by poly(N-vinyl-2-pyrro- lidone) anchored palladium catalyst affords β,r-butonic acid under atmo- spheric pressure and at room temperature.The activity and efficiency of the catalyst are much higher than those of the reported catalysts for this reaction.展开更多
基金supported by State Key Laboratory for Tunnel Engineering(TESKL202425)the National Natural Science Foundation of China(Grant Nos.U24A2085,52174096,52304110)+1 种基金the Henan Province Key Research and Development Program(Grant Nos.241111322000)the Henan Provincial Science and Technology Research Project(Grant Nos.252102320020)。
文摘In geotechnical engineering applications,including mining and tunnel construction,the stability of fractured rock masses is paramount to ensuring structural safety.The spatial distribution and temporal evolution of internal fractures fundamentally govern the mechanical behavior and failure mechanisms of rock masses.Nevertheless,the inherent complexity and structural concealment of rock mass systems pose significant challenges for the direct measurement of critical internal mechanical parameters.This study explores the use of deep learning to invert mechanical responses of NPR(Negative Poisson's Ratio)anchored fractured rock masses.Discrete Element Method(DEM)simulations were conducted to generate datasets including stress-strain curves and crack numbers under various initial fracture distributions.Three models—GRU,CNN+GRU,and CNN+GRU+ATT—were developed to predict rock mechanical parameters from NPR cable force data.Results show that the CNN+GRU+ATT model achieves superior accuracy,with R^(2)>0.90 and RMSE<5 on stress prediction tasks.It also accurately estimates initial crack quantity(np),with mean prediction error under 10%for high-fracture scenarios.The proposed model effectively captures stress fluctuations,offering early-warning potential for failure.The approach demonstrates strong generalization and robustness across varying crack configurations,providing a feasible framework for real-time health monitoring and mechanical parameter estimation in fractured rock engineering.
基金supported by the National Natural Science Foundation of China(No.52174081)the National Key Scientific Instruments and Equipment Development Projects of China(No.52227901)。
文摘Weak structural planes commonly exist in underground engineering.These planes make anchor structures more prone to failure,threatening rock stability,threatening the safety and stability of underground engineering.Optical-Thermal-Acoustic(OTA)monitoring was applied during uniaxial compression tests on cross-layer anchored rock masses.The study revealed the mechanical properties,failure characteristics,and energy evolution of rock masses with different anchoring methods and bedding angles.Key findings:anchoring suppresses transverse deformation and tensile crack propagation,increasing elastic modulus and bearing capacity;anchored rock shows more intense acoustic emission but smaller infrared temperature changes;the structural plane angle controls the direction of crack extension and the evolution of the strain characteristics,and the rock is prone to instantaneous slip failure of the structural surface at 45°–75°,and the lower strength with significant IR change characteristics.Distinct OTA characteristics during rupture validate the method's reliability for rockburst early warning and intensity assessment.Moreover,based on the failure characteristics of cross-layer anchored rock masses,a shear failure criterion for anchored structural planes is established.This criterion enables prediction of rock mass failure modes,analysis of bolt support resistance,reference for support design/construction in underground engineering within complex strata.
基金supported by the National Natural Science Foundation of China(grant no.52273044,52373092)the Opening Project of State Key Laboratory of Polymer Materials Engineering(Sichuan University)(grant no.sklpme2023-3-4)+1 种基金the Key Research Program of Zhejiang Province(grant no.2023C01101,2023C01210,2022C01049,2022C01205)the Natural Science Foundation of Zhejiang Province(grant no.LY20E030008).
文摘The increasingly serious electromagnetic(EM)radiation and related pollution effects have gradually attracted people's attention in the information age.Hence,it's crucial to develop adaptive shielding materials with minimum EM waves(EMW)reflection.In this paper,Ag nanoparticles loaded mesoporous carbon hollow spheres(MCHS@Ag)were synthesized by chemical reduction method,and cellulose nanofibers(CNF)/MXene/MCHS@Ag homogeneous composites were prepared.The total EM interference shielding efficiency(SET)of CNF/MXene/MCHS@Ag composite film was 32.83 dB(at 12.4 GHz),and the absorption effectiveness(SEA)was improved to 26.6 dB,which was 63.1%and 195.5%higher than that of CNF/MXene/MCHS composite film.The low dielectric property of MCHS effectively optimized the impedance matching between the composites and air.The hollow porous structure prolonged the transmission path of EMW and increased the absorption loss of the composites.At the same time,Ag nanoparticles located the MCHS were helpful to construct the internal conductive path overcoming the damage of the conductive property caused by the low dielectric of MCHS.This research adopts a straightforward method to construct a lightweight,pliable,and mesoporous composites for EMI shielding,which serves a crucial role in the current era of severe EM pollution.
基金supported by the National Key Research and Development Program of China(No.2023YFC2907600)the National Natural Science Foundation of China(Nos.42477166 and 42277174)+2 种基金the Fundamental Research Funds for the Central Universities,China(No.2024JCCXSB01)the Opening Project of State Key Laboratory of Explosion Science and Safety Protection,Beijing Institute of Technology(No.KFJJ24-01M)the Open Foundation of Collaborative Innovation Center of Green Development and Ecological Restoration of Mineral Resources(No.HLCX2024-04)。
文摘With resource exploitation and engineering construction gradually going deeper,the surrounding rock dynamic disaster becomes frequent and violent.The anchorage support is a common control method of surrounding rock in underground engineering.To study the dynamic damage characteristics of anchored rock and the energy absorption control mechanism of dynamic disasters,a new type of constant resistance and energy absorption(CREA)material with high strength,high elongation and high energy absorption characteristics is developed.A contrast test of rockbursts in anchored rock with different support materials is conducted.The test results show that the surface damage rates and energy release degree of anchored rock with common bolt(CB)and CREA are lower than those of unanchored rock,respectively.The total energy,average energy and maximum energy released by CREA anchored rock are 30.9%,94.3%and 84.4%lower than those of CB anchored rock.Compared with unanchored rock,the rockburst peak stress in the CREA anchored rock is increased by 39.9%,and the rockburst time is delayed by 53.2%.Based on the rockburst energy calculation model,the evolution law of rockburst peak stress and energy release is investigated.The control mechanism of CREA support units on rock dynamic failure is clarified.
文摘In this paper is presented a concept solution and acceptance test application procedure of deep pit protection structure,intended for three underground levels of residential building:A,B,C,D,block 10C,Budva,Montenegro.The anchored wall used consist of nongravity cantilevered walls with three levels of ground anchors.Nongravity cantilevered walls employ continuous walls constructed in slurry trenches(i.e.,slurry(diaphragm)walls),e.g vertical elements that are drilled to depths below the finished excavation grade.For those nongravity cantilevered walls,support is provided through the shear and bending stiffness of the vertical wall elements and passive resistance from the soil below the finished excavation grade.Anchored wall support relies on these components as well as lateral resistance provided by the ground anchors to resist horizontal pressures(e.g.,earth,water,external loads)acting on the wall.Anchored wall analysed and applied is temporary supporting structure necessary for the excavation and erection of the underground structure part up to ground surface level.Temporary ground anchors lifetime is up to two years.Dynamic loads are not considered.
基金Projects(51927807,52074164,42477166,42077267,42277174)supported by the National Natural Science Foundation of ChinaProject(2024JCCXSB01)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(KFJJ24-01M)supported by the State Key Laboratory of Explosion Science and Safety Protection,Beijing Institute of Technology,China。
文摘Rockburst is a common disaster in deep underground engineering,which seriously impacts project construction safety.Understanding its causes and burst resistance mechanism is of significance for rockburst prevention and mitigation.We developed a new type of high strength,large elongation,and strong energy-absorbing material,and conducted comparative tests on both basic and anchored rock specimens with such material.We analyzed the rockburst process,energy release and peak stress of the rock,and force and deformation withstood by the energy-absorbing bolts.The experimental results show that the energy reduction rate of the rocks reinforced by energy-absorbing bolts is more than 80%,compared with that of the basic rock.The force exerted on the energy-absorbing bolts increases suddenly when the rockburst occurs,and the strength utilization rates of the energy-absorbing bolts under strain rockburst and impact rockburst conditions are 73.3%and 61.2%,respectively.Rockburst also causes non-uniform shear deformation of the anchor bolt.Based on the rockburst energy criterion,the peak stress of the anchored rock is 2.2 times and 2.5 times the uniaxial compressive strength of the rock,respectively,under strain rockburst and impact rockburst conditions.The energy required for rockburst is 396.0 and 478.4 kJ/m^(3),respectively.The energy-anchoring bolts can effectively reduce the likelihood of rockburst.The results can provide a reference for support design for burst-prone rock in underground engineering.
文摘A new capillary gas chromatography stationary phase, monokis (2,6 di O benzyl 3 O propyl (3’)) hexakis(2,6 di O benzyl 3 O methyl) β CD bonded polysiloxane, was synthesized. It exhibited separation abilities to disubstituted benzene isomers and some chiral solutes. It was also found that the polarity of CD derivatives can be lowered both by chemically bonding it to polysiloxane and by diluting it in polysiloxane. The separation abilities of the polysiloxane anchored CDs (SP CD) are higher than that of the unbonded CDs (S CD) and the diluted S CD at lower column temperature. Hydrosilylation reaction is one of the best methods to lower the operating temperature of CDs.
基金financially supported by the National Natural Science Foundation of China(No.U2030208&22279082)Sichuan Science and Technology Program(2025YFHZ0056)。
文摘The development of high-performance metal nanocluster catalysts is hindered by a fundamental stabilization-activity trade-off.Oxide supports often induce over-stabilization via insulating overlayers that block active sites,while conventional functionalized carbon supports suffer from thermodynamic instability and weak metal-support electronic coupling,leading to aggregation.Herein,a novel defectmediated covalent anchoring strategy is presented to immobilize transition metal(Pd,Ru,and Ir)NCs within ordered mesoporous carbon.This approach leverages intrinsic micropore defects to capture precursors and facilitate in-situ formation of direct metal-carbon covalent bonds.Controlled pyrolysis confines metal atom sintering into clusters within the mesopores,achieving high metal loading.This enrooted architectu re uniquely balances stability and activity:it avoids the excessive metal-carbon bonding detrimental to single-atom catalysts while maintaining sufficient,controllable interactions.The resulting Pd NCs catalyst exhibits exceptional hydrogen oxidation reaction activity,surpassing mass activity benchmarks of conventional Pt/C.Critically,this methodology decouples atomic-scale stabilization from catalytic site accessibility,resolving the long-standing activity-stability dilemma and providing a generalizable platform for fabricating stable,high-loading cluster catalysts with optimized electronic structures.
基金Supported by National Natural Science Foundation of China(Major Instrumental Program)No.81127005the Science and Technology Innovation Project of Shaanxi Province,China,No.S2016TNGY0119
文摘AIM To design a miniature magnetically anchored and controlled camera system to reduce the number of trocars which are required for laparoscopy.METHODS The system consists of a miniature magnetically anchored camera with a 30° downward angle, an external magnetically anchored unit, and a vision output device. The camera weighs 12 g, measures Φ10.5 mm × 55 mm and has two magnets, a vision model, a light source, and a metal hexagonal nut. To test the prototype, the camera was inserted through a 12-mm conventional trocar in an ex vivo real liver laparoscopic training system. A trocar-less laparoscopic cholecystectomy was performed 6 times using a 12-mm and a 5-mm conventional trocar. In addition, the same procedure was performed in four canine models.RESULTS Both procedures were successfully performed using only two conventional laparoscopic trocars. The cholecystectomy was completed without any major complication in 42 min(38-45 min) in vitro and in 50 min(45-53 min) using an animal model. This camera was anchored and controlled by an external unit magnetically anchored on the abdominal wall. The camera could generate excellent image. with no instrument collisions.CONCLUSION The camera system we designed provides excellent optics and can be easily maneuvered. The number of conventional trocars is reduced without adding technical difficulties.
基金supported by the National Natural Science Foundation of China(Grant Nos.52174096 and 51874311)。
文摘This study compares the strength characteristics of rocks anchored by NPR bolts and ordinary bolts with varied preloads,based on the mechanical properties of NPR bolts(with a negative Poisson’s ratio).The results show that the uniaxial compressive stress-strain curve of ordinary anchored rocks exhibits noticeable abrupt changes.After reaching peak strength,the bolt breaks,whereas the stress-strain curve of NPR-anchored rocks is smoother.The NPR bolt enters the stage of continuous resistance after reaching maximal strength and does not break.As the preload increases,the strength of the anchored rock grows linearly.A calculation equation for the strength of the anchored rock is proposed based on the preload.The theoretical equation fits the test results well,and the fitted parameters show that NPR bolts can better increase the strength of the rock.The concept of dynamic toughness UC of anchored rock is proposed to reflect the comprehensive mechanical properties of anchored rock,including strength and plasticity.As the preload increases,the UC of ordinary anchored rock first decreases and then increases,while the UC of the NPR anchored rock does not change significantly with the preload when the strain is small,and the UC increases with the increase of the preload when the strain is large.
基金supported by the National Natural Science Foundation of China(No.U2006225)the European Union’s Horizon 2020 Marie Sklodowska-Curie Research and Innovation Staff Exchange Programme(No.778360)。
文摘Rock-embedded foundations with good uplift and bearing capacity are often used in mountains or hilly areas.However,there are soil layers with a certain thickness on the rocks in these mountainous areas,and the utilization of those soil layers is a problem worthy of attention in foundation construction.Considering construction-and cost-related factors,traditional single-form foundations built on such sites often cannot provide sufficient resistance against uplift.Therefore,an anchored pier foundation composed of anchors and belled piers,specifically constructed for such conditions,can be invaluable in practice.This paper introduces an experimental and analytical study to investigate the uplift capacity and the uplift mobilization coefficients(UMCs)of the anchored pier foundation.In this study,three in-situ monotonic pullout tests were carried out to analyze the load–displacement characteristics,axial force distribution,load transfer mechanism,and failure mechanism.A hyperbolic model is used to fit the load–displacement curves and to reveal the asynchrony of the ultimate limit states(ULSs)of the anchor group and the belled pier.Based on the results,the uplift capacity can be calculated by the UMCs and the anchor group and pier uplift capacities.Finally,combined with the estimation of the deformation modulus of the soil and rock,the verification calculation of the uplift capacity and UMC was carried out on the test results from different anchored pier foundations.
基金The National Natural Science Foundation of China(No.61503303,51409215)the Fundamental Research Funds for the Central Universities(No.G2015KY0102)
文摘To improve the accuracy of illumination estimation while maintaining a relative fast execution speed, a novel learning-based color constancy using color edge moments and regularized regression in an anchored neighborhood is proposed. First, scene images are represented by the color edge moments of various orders. Then, an iterative regression with a squared Frobenius norm（F-norm） regularizer is introduced to learn the mapping between the edge moments and illuminants in the neighborhood of the anchored sample.Illumination estimation for the test image finally becomes the nearest anchored point search followed by a matrix multiplication using the associated mapping matrix which can be precalculated and stored. Experiments on two standard image datasets show that the proposed approach significantly outperforms the state-of-the-art algorithms with a performance increase of at least 10. 35% and 7. 44% with regard to median angular error.
基金National Natural Science Foundation of China( 5 986 80 0 1)
文摘The thinking of co evolution is applied to the optimization of retaining and protecting structure for deep foundation excavation, and the system of optimization of anchored row piles for deep foundation pit has been already developed successfully. For the co evolution algorithm providing an evolutionary mechanism to simulate ever changing problem space, it is an optimization algorithm that has high performance, especially applying to the optimization of complicated system of retaining and protecting for deep foundation pit. It is shown by many engineering practices that the co evolution algorithm has obvious optimization effect, so it can be an important method of optimization of retaining and protecting for deep foundation pit. Here the authors discuss the co evolution model, object function, all kinds of constraint conditions and their disposal methods, and several key techniques of system realization.
文摘Both aliphatic and aromatic ketones are efficiently transfer-hydrogenated by propan-2-ol under mild conditions in the presence of a catalytic amount of poly(2,6-dimethyl-1,4-Phenylene oxide) (PPO) anchored ruthenium complex and sodium hydroxide. An important feature of this polymer anchored catalyst is its stability in air.
基金financially supported by Central Public-interest Scientific Institution Basal Research Fund,CAFS(Grant Nos.2023TD88,2024HY-ZC005,and 2024XT0801).
文摘Fishing boats are usually anchored side by side in the harbor because of the small structural size and poor resistance to wind and waves.A series of physical model experiments are conducted to investigate the motion characteristics of multiple fishing boats that are moored together.A decay test in calm water is conducted to study the natural period and damping coefficients.Regular wave experiments are performed to analyze the roll motion response of each boat for four modes(different numbers of boats side-by-side).The results indicate that the“natural period”of each boat for the mode of multi-boats especially three or four boats,is slightly smaller than that of a single boat,whereas the damping coefficient is visibly larger than that of a single boat.The maximum roll angle of each boat does not appear at the same time under a 90°incident wave.Small roll motion energy is generated at low frequencies and high frequencies when multiple boats are moored together.The energy decreases with the increasing wave period.The roll motion responses of each boat in four modes exhibit different trends with the increasing wave frequency.The number of boats and boat position have significant effects on roll motion.
文摘Oxygen reduction reaction(ORR)is the key reaction at the cathode of proton exchange membrane fuel cells(PEMFCs)and metal-air batteries(1)To address the challenges associated with Pt-based electrocatalysts having prominent activity for ORR,e.g.scarce abundance,prohibitive cost,poor stability,and vulnerability to reaction intermediates,it is necessary to explore other cost-effective ORR electrocatalysts with competitive or even superior performance to promote the commercialization of the energy conversion devices.
基金the National Natural Science Foundation of China(Nos.21971132 and 52072197)Outstanding Youth Foundation of Shandong Province,China(No.ZR2019JQ14)+7 种基金Youth Innovation and Technology Foundation of Shandong Higher Education Institutions,China(No.2019KJC004)Major Scientific and Technological Innovation Project(No.2019JZZY020405)Major Basic Research Program of Natural Science Foundation of Shandong Province(No.ZR2020ZD09)Taishan Scholar Young Talent Program(No.tsqn201909114)the Key Laboratory of Resource Chemistry,Ministry of Education(No.KLRC_ME2101)Scientific and Technological Innovation Promotion Project for Small-medium Enterprises of Shandong Province(No.2022TSGC1257)Major Research Program of Jining City(No.2020ZDZP024)The 111 Project of China(No.D20017).
文摘Lithium (Li)-CO_(2) battery is rising as an attractive energy-storage system with the competence of CO_(2) conversion/fixation. However, its practical development is seriously hindered by the high overpotential. Herein, a rational design on a highly catalytic Li-CO_(2) battery electrode built by graphdiyne powder as a multi-functional laminar scaffold with anchored highly dispersed Ru nanoparticles is explored. The strong interaction between the abundant acetylenic bond sites of graphdiyne scaffold and Ru nanoparticles can effectively promote the electrochemical progress and reduce the voltage polarization. The unique channels architecture of the cathodic catalyst with enough space not only accelerates CO_(2) diffusion and electrons/Li+ transport, but also allows a large amount of accommodation for discharged product (Li2CO3) to assure an advanced capacity. The corresponding Li-CO_(2) battery displays an advanced discharged capacity of 15,030 mAh/g at 500 mA/g, great capacity retention of 8873 mAh/g at 2 A/g, high coulombic efficiency of 97.6% at 500 mA/g and superior life span for 120 cycles with voltage gap of 1.67 V under a restricted capacity of 1000 mAh/g at 500 mA/g. Ex/in-situ studies prove that synergy between Ru nanoparticles and acetylene bonds of GDY can boost the round-trip CO_(2)RR and CO_(2)ER kinetics.
基金provided by the National Natural Science Foundation of China(52074300)the Program of China Scholarship Council(202206430024)+2 种基金the National Natural Science Foundation of China Youth Science(52104139)Yueqi Young Scholars Project of China University of Mining and Technology Beijing(2602021RC84)Guizhou province science and technology planning project([2020]3007,[2020]3008)。
文摘The deep mining of coal resources is accompanied by severe environmental challenges and various potential engineering hazards.The implementation of NPR(negative Poisson's ratio)bolts are capable of controlling large deformations in the surrounding rock effectively.This paper focuses on studying the mechanical properties of the NPR bolt under static disturbance load.The deep nonlinear mechanical experimental system was used to study the mechanical behavior of rock samples with different anchored types(unanchored/PR anchored/2G NPR anchored)under static disturbance load.The whole process of rock samples was taken by high-speed camera to obtain the real-time failure characteristics under static disturbance load.At the same time,the acoustic emission signal was collected to obtain the key characteristic parameters of acoustic emission such as acoustic emission count,energy,and frequency.The deformation at the failure of the samples was calculated and analyzed by digital speckle software.The findings indicate that the failure mode of rock is influenced by different types of anchoring.The peak failure strength of 2G NPR bolt anchored rock samples exhibits an increase of 6.5%when compared to the unanchored rock samples.The cumulative count and cumulative energy of acoustic emission exhibit a decrease of 62.16%and 62.90%,respectively.The maximum deformation of bearing capacity exhibits an increase of 59.27%,while the failure time demonstrates a delay of 42.86%.The peak failure strength of the 2G NPR bolt anchored ones under static disturbance load exhibits an increase of 5.94%when compared to the rock anchored by PR(Poisson's ratio)bolt.The cumulative count and cumulative energy of acoustic emission exhibit a decrease of 47.16%and 43.86%,respectively.The maximum deformation of the bearing capacity exhibits an increase of 50.43%,and the failure time demonstrates a delay of 32%.After anchoring by 2G NPR bolt,anchoring support effectively reduces the risk of damage caused by static disturbance load.These results demonstrate that the support effect of 2G NPR bolt materials surpasses that of PR bolt.
基金the National Natural Science Foundation of China(Nos.61876112,61303104,61601311,61603022,61373090 and 61203238)the Natural Science Foundation of Beijing(Nos.4162017 and 4132014)+4 种基金the Support Project of High-Level Teachers in Beijing Municipal Universities in the Period of 13th Five-Year Plan(No.CIT&TCD20170322)the Project of Beijing Excellent Talents(No.2016000020124G088)the Beijing Municipal Education Research Plan Project(No.SQKM201810028018)the Capacity Building for Sci-Tech Innovation-Fundamental Scientific Research Funds(No.025185305000/134/187/188/189)the Youth Innovative Research Team of Capital Normal University
文摘Although progress in face recognition is encouraging, the accuracy rate of face recognition remains to be increased. Since the face image quality has a positive influence on face recognition accuracy, the image enhancement methods are popular in face recognition. Most current image enhancement methods aim at improving visual appearance, but cannot improve recognition accuracy remarkably. In this paper, a feature evaluation operator is designed to overcome this problem. The operator selects patches with the best quality, and then face image is reconstructed with the selected patches. The proposed algorithm is tested on two different face recognition applications. Accuracy is raised after enhancement, and the result proves that the proposed algorithm is effective.
文摘Carbonylation of allyl halides catalyzed by poly(N-vinyl-2-pyrro- lidone) anchored palladium catalyst affords β,r-butonic acid under atmo- spheric pressure and at room temperature.The activity and efficiency of the catalyst are much higher than those of the reported catalysts for this reaction.
