With the arrival of the era of big data,the basic research of mathematics has attracted unprecedented attention all over the country.To meet the needs of the development of the times,the construction of mathematics di...With the arrival of the era of big data,the basic research of mathematics has attracted unprecedented attention all over the country.To meet the needs of the development of the times,the construction of mathematics discipline has become one of the important tasks of higher mathematics teaching.Starting from the demand orientation,this paper deeply analyzes the problems existing in mathematics education at the present stage,and constructs the construction path of mathematics discipline based on demand orientation.展开更多
Since modern ecology studies the relationships between living things and their environments,the philosophies correlating to it has become optimal preferences in evaluating disputes arising in economic,political,cultur...Since modern ecology studies the relationships between living things and their environments,the philosophies correlating to it has become optimal preferences in evaluating disputes arising in economic,political,cultural,and even pedagogical fields.The study of this paper proclaims that ecology oriented college English classroom construction in China is conducive to stimulating the classroom vitalities,and ensuring the sustainable development of teaching order.展开更多
This paper describes the influence of joint spacing and joint orientation on the penetration rate of a Tunnel Boring Machine (TBM) disc cutter as modeled by the Discrete Element Method (DEM). The input data for th...This paper describes the influence of joint spacing and joint orientation on the penetration rate of a Tunnel Boring Machine (TBM) disc cutter as modeled by the Discrete Element Method (DEM). The input data for the siLmulations were obtained from the sandstone along the AIborz tunnel that is currently being excavated in Iran using a 5.2 m diameter open TBM. Three joint spacings, 150, 200, and 300 mm, were modeled together with seven values of joint orientation; 0°, 15°, 30°, 45°, 60°, 75°, and 90°. The results show that the penetration increases when joint orientation increases from 0° to 75°, but it decreases as the joint orientation increases further from 75° to 90°. This is true for each joint spacing. In addition, for a given joint orientation increasing the joint spacing causes the TBM penetration to decrease. The optimum joint orientation, from the viewpoint of TBM penetration, is about 60-75°.展开更多
Modularized construction is a new type of prefabricated building system with green environmental protection and excellent performance. There are few studies on the seismic performance of its key connection joint. This...Modularized construction is a new type of prefabricated building system with green environmental protection and excellent performance. There are few studies on the seismic performance of its key connection joint. This paper presents a new type of assembled connection joint for the high-rise modularized construction. Cyclic shear tests of full-scale joints were carried out, and the key indexes of their seismic performances including the hysteretic performance, ductility, and energy dissipation capacity were analyzed and obtained. The results show that the hysteresis loops of longitudinal and lateral cyclic shear tests were both plump in shapes. The ductility coefficients were 4.54 and 4.98, and the energy dissipation coefficients were 1.83 and 1.43, respectively. The test joint had good ductility and energy dissipation capacity. The positions of yield failure of specimens were mainly concentrated in the connection areas between the column and short beam or end-plate. The research can provide the technical reference for the seismic design and engineering application of related modularized constructions.展开更多
On December 20,2016 the construction of the SinoKuwait Guangdong integrated refining/chemical join venture project,which is the largest Sinopec’s projec under construction and also the key construction project of Gua...On December 20,2016 the construction of the SinoKuwait Guangdong integrated refining/chemical join venture project,which is the largest Sinopec’s projec under construction and also the key construction project of Guangdong province,had been kicked off comprehensively.This project is located in the new district of the East Sea Island inside the Zhanjiang Economic Development展开更多
The paper proposes a new multiple-factor clustering method(NMFCM)with consideration of both box fractal dimension(BFD)and orientation of joints.This method assumes that the BFDs of different clusters were uneven,and c...The paper proposes a new multiple-factor clustering method(NMFCM)with consideration of both box fractal dimension(BFD)and orientation of joints.This method assumes that the BFDs of different clusters were uneven,and clustering was performed by redistributing the joints near the boundaries of clusters on a polar map to maximize an index for estimating the difference of the BFD(DBFD).Three main aspects were studied to develop the NMFCM.First,procedures of the NMFCM and reasonableness of assumptions were illustrated.Second,main factors affecting the NMFCM were investigated by numerical simulations with disk joint models.Finally,two different sections of a rock slope were studied to verify the practicability of the NMFCM.The results demonstrated that:(1)The NMFCM was practical and could effectively alleviate the problem of hard boundary during clustering;(2)The DBFD tended to increase after the improvement of clustering accuracy;(3)The improvement degree of the NMFCM clustering accuracy was mainly influenced by three parameters,namely,the number of clusters,number of redistributed joints,and total number of joints;and(4)The accuracy rate of clustering could be effectively improved by the NMFCM.展开更多
The new adhesive material for the construction joints of tunnel lining(named as SZC) was studied based on the structural characteristics of interfaces and the characteristic of bonding construction, and the performanc...The new adhesive material for the construction joints of tunnel lining(named as SZC) was studied based on the structural characteristics of interfaces and the characteristic of bonding construction, and the performance indexes were verified by tests. The experimental results show that the adhesive capability of interface is improved effectively by using SZC material, the properties, such as anti-freezing, erosion-resistance and anti-shrinkage are improved greatly as well as durability.展开更多
In the Republic of Kazakhstan, the regulatory framework in construction based on Eurocodes has been in force since 2015. However, Kazakhstani produced steel has not been studied for compliance with the requirements of...In the Republic of Kazakhstan, the regulatory framework in construction based on Eurocodes has been in force since 2015. However, Kazakhstani produced steel has not been studied for compliance with the requirements of Eurocode 1993. This has resulted in limited use of Kazakhstani structural steel in construction. The feasibility of using structural steel in welded joints has been experimentally investigated. To verify the application of such joints in construction, including earthquake engineering, experimental studies of welded joints made of structural steel produced by Arcelor-Mittal in Temirtau have been carried out. In total, 7 types of structural steel of various thicknesses were selected. Five specimens have been used in each series of tests. The Brinell hardness values of the weld joint, yield strength of steel and tensile strength, relative rupture strain were determined. It was found that for all types of structural steel, the quality of weld joints complied with the requirements of Eurocode 1993—a sample rupture appeared along the plates (main body of the metal), not along the weld joints. It has been established that structural steel produced in the Republic of Kazakhstan fully complies with the requirements of Eurocode 1993. The studies on the dependence of Brinell hardness values of weld joint steel on the yield strength, tensile strength and relative rupture strain have been carried out. The correlation dependences between the values of yield strength of steel and tensile strength, relative rupture strain and BH Brinell hardness were studied. The results of work will allow for significantly increasing the use of Kazakhstani structural steel in seismic and conventional areas of the Republic of Kazakhstan.展开更多
On the basis of analyzing cases of existing rural collectively owned profit-oriented construction land entering into trading market,this paper put forward several thoughts,introduced methods and paths for rural collec...On the basis of analyzing cases of existing rural collectively owned profit-oriented construction land entering into trading market,this paper put forward several thoughts,introduced methods and paths for rural collectively owned profit-oriented construction land entering into trading market,including reforming rural collective land property right system,cultivating new rural collective economy organizations,helping them to become market entities; improving various legal systems,making clear range of construction land entering into trading market; formulating scientific benefit allocation mechanism; establishing fair and transparent decision making mechanism.展开更多
Columnar jointed rock mass with unique geometric and geological properties is one spectacular example of geometrical order in nature.Columnar joints are generally accepted to be formed by spatially uniform volume cont...Columnar jointed rock mass with unique geometric and geological properties is one spectacular example of geometrical order in nature.Columnar joints are generally accepted to be formed by spatially uniform volume contraction during cooling.In this paper,substantial field work was performed to study the geological characteristics of irregular columnar jointed basalt on the left bank dam foundation in the Baihetan Hydropower Station,where the columnar jointed rock mass is extensively exposed due to excavation.The quantitative measurements of the sizing of polygonal crack pattern of columnar joints and assessment of their degree of irregularity were summarized.Considering the irregularity of polygonal crack pattern,a modified Voronoi polygon(MVP)method was developed to model the special polygonal crack pattern of columnar joints.The new polygonal pattern obtained by the MVP method consists of a large number of irregular polygons,of which the degree of irregularity is consistent with the field measurement results.This method can reproduce the rapid evolution from an initial ideal regular hexagonal pattern to a final actual irregular polygonal pattern as the degree of irregularity increases.The compression tests of columnar jointed rock mass with different irregularity show that the geometric irregularity has a great influence on its mechanical properties.This numerical construction method provides a reliable way to reconstruct columnar joint structure with specific polygonal crack pattern,which is consistent with onsite columnar jointed basalt.展开更多
Model tests and numerical calculations were adopted based on the New Yuanliangshan tunnel project to investigate the water pressure resistance of lining construction joints in high-pressure and water-rich karst tunnel...Model tests and numerical calculations were adopted based on the New Yuanliangshan tunnel project to investigate the water pressure resistance of lining construction joints in high-pressure and water-rich karst tunnels.A large-scale model test was designed and conducted,innovatively transforming the external water pressure of the lining construction joint into internal water pressure.The effects of the embedded position and waterstop type on the water pressure resistance of the construction joint were analyzed,and the reliability of the model test was verified via numerical calculations.The results show that using waterstops can significantly improve the water pressure resistance of lining construction joints.The water pressure resistance of the lining construction joint is positively correlated with the lining thickness and embedded depth of the waterstop.In addition,the type of waterstop significantly influences the water pressure resistance of lining construction joints.The test results show that the water pressure resistance of the embedded transverse reinforced waterstop is similar to that of the steel plate waterstop,and both have more advantages than the rubber waterstop.The water pressure resistance of the construction joint determined via numerical calculations is similar to the model test results,indicating that the model test results have high accuracy and reliability.This study provides a reference for similar projects and has wide applications.展开更多
Background Determination of the proper orientation of the knee articular surface is required both for correction of knee malalignment by osteotomy and for correct component alignment in knee arthroplasty. We sought to...Background Determination of the proper orientation of the knee articular surface is required both for correction of knee malalignment by osteotomy and for correct component alignment in knee arthroplasty. We sought to determine whether the patients' sex and lower extremity alignment (hip-knee-ankle angle) affects proper knee realignment in osteotomy or component alignment in total knee arthroplasty. Methods We examined 199 healthy adult knees with malalignment of 〈5°to determine the mechanical medial distal femoral angle, mechanical medial proximal tibial angle, surgical transepicondylar axis angle, and discrepancies between bone-cut orientations of osteotomy or total knee arthroplasty and the joint line of the distal femoral condyles, posterior femoral condyles and proximal tibial plateaus, using a three-dimensional computed tomography model. Results The mean mechanical medial distal femoral angle and mean mechanical medial proximal tibial angle were (94.4±1.9)° and (87.6±1.8)° respectively for women and (93.8±2.0)° and (87.1±1.4)° respectively for men. The surgical transepicondylar axis angle was (2.9±1.6)° for women and (3.2±1.7)° for men. Independent of sex, the hip-knee-ankle angle was closely related to the mechanical medial distal femoral angle and mechanical medial proximal tibial angle, but not to the surgical transepicondylar axis angle. A slightly more valgus alignment of the knee and a more valgus angulation of the distal femoral joint line were found in women, whereas a more varus angulation of the proximal tibial joint line was found in men. Sex had the greatest effect on knee joint line orientation when the lower extremity was valgus in alignment. Conclusions A more valgus femoral joint line can be expected in women and in persons with valgus lower extremity aliqnment; a more varus tibial joint line can be found in men and in persons with varus lower extremity alignment.展开更多
In order to well protect Chinese ancient buildings, aseismic behaviors of Chinese ancient tenon-mortise joints strengthened by carbon fibre reinforced plastic (CFRP) are studied by experiments. Based on the actual s...In order to well protect Chinese ancient buildings, aseismic behaviors of Chinese ancient tenon-mortise joints strengthened by carbon fibre reinforced plastic (CFRP) are studied by experiments. Based on the actual size of an ancient building, a wooden frame model with a scale of 1 : 8 of the prototype structure is built considering the swallow-tail type of tenon-mortise connections. Low cyclic reversed loading tests are carried out including three groups of unstrengthened structures and two groups of structures strengthened with CFRP. Based on experimental data, moment-rotation angle hysteretic curves and skeleton curves for each joint are obtained. The energy dissipation capability, stiffness degradation and deformation performance of the joints before and after being strengthened are also analyzed. Results show that after being strengthened with CFRP, the tenon value pulled out of the mortise is reduced; the bending strength and the energy dissipation capabilities of the joint are enhanced; stiffness degradation of the joint is not obvious; and the deformation performance of the joint remains good. Thus, the CFRP has good effects on strengthening the tenon-mortise joints of Chinese ancient buildings.展开更多
In this study,a fully precast steel—ultrahigh performance concrete(UHPC)lightweight composite bridge(LWCB)was proposed based on Mapu Bridge,aiming at accelerating construction in bridge engineering.Cast-in-place join...In this study,a fully precast steel—ultrahigh performance concrete(UHPC)lightweight composite bridge(LWCB)was proposed based on Mapu Bridge,aiming at accelerating construction in bridge engineering.Cast-in-place joints are generally the controlling factor of segmental structures.Therefore,an innovative girder-to-girder joint that is suitable for LWCB was developed.A specimen consisting of two prefabricated steel—UHPC composite girder parts and one post-cast joint part was fabricated to determine if the joint can effectively transfer load between girders.The flexural behavior of the specimen under a negative bending moment was explored.Finite element analyses of Mapu Bridge showed that the nominal stress of critical sections could meet the required stress,indicating that the design is reasonable.The fatigue performance of the UHPC deck was assessed based on past research,and results revealed that the fatigue performance could meet the design requirements.Based on the test results,a crack width prediction method for the joint interface,a simplified calculation method for the design moment,and a deflection calculation method for the steel—UHPC composite girder in consideration of the UHPC tensile stiffness effect were presented.Good agreements were achieved between the predicted values and test results.展开更多
This study was undertaken to determine the bending strength properties of off-cut Yellow Meranti wood by applying the finger jointed techniques. The finger orientations that were used in this study are vertical and ho...This study was undertaken to determine the bending strength properties of off-cut Yellow Meranti wood by applying the finger jointed techniques. The finger orientations that were used in this study are vertical and horizontal finger orientation. Specimens were bonded with PVAc (polyvinyl acetate). The bending strength properties were determined by the three point and four point bending test method. The results show that vertical finger orientation has the higher mean of modulus of rupture and the modulus of elasticity value of 24.49 MPa (28.91 MPa) and 8,814 MPa (11,668 MPa) respectively. However, the tested specimen properties did not meet the minimum strength of the solid (control) specimens.展开更多
Automatic return oriented programming (ROP) technology can effectively improve the efficiency of ROP constructed, but the existing research results still have some shortcomings including needing more address space, ...Automatic return oriented programming (ROP) technology can effectively improve the efficiency of ROP constructed, but the existing research results still have some shortcomings including needing more address space, poor generality. In order to solve these problems, this paper presents an improved ROP auto-constructor QExtd. Firstly, we design a Turing-complete language QExtdL and provide the basis of gadgets analysis. Secondly, we represent the MI instruction and realize precise process of side-effect instructions for improving the efficiency of automatic construction. At last, we establish a three-layer language conversion mechanism, making it convenient for users to construct ROP. Theoretical and experimental data show that the QExtd automatic construction method is much better than the ROPgadget based on syntax. In addition, the proposed method succeeds in constructing gadgets of ROP with the probability of 84% for programs whose sizes are more than 20 KB and whose directory is "/usr/bin" in Ubuntu, which proves that the construction capability improves significantly.展开更多
1 Project positioning Baihetan Hydropower Station is classified as the second of the four hydropower cascades in the lower reaches of the Jinsha River:Wudongde,Baihetan,Xiluodu and Xiangjiaba.As an important backbone ...1 Project positioning Baihetan Hydropower Station is classified as the second of the four hydropower cascades in the lower reaches of the Jinsha River:Wudongde,Baihetan,Xiluodu and Xiangjiaba.As an important backbone project for China to implement the strategy of West-to-East Power Transmission and optimize the energy structure,it constitutes an important part of the Yangtze River flood control system.Located at the junction of Ningnan County,Sichuan Province and Qiaojia County,Yunnan Province,the hydropower station is the largest hydropower project under construction in the world,with a unit capacity of million-kilowatts ranking the highest in the world and a total installed capacity of 16 million kW,second only to the Three Gorges Project,ranking the second in the world.展开更多
The article deals with musical heritage of some Orient cultures, joint singing as one of the main part of music art from ancient time to nowadays. The measure reflecting live process of national musical art is a perfo...The article deals with musical heritage of some Orient cultures, joint singing as one of the main part of music art from ancient time to nowadays. The measure reflecting live process of national musical art is a performing practice. Makom is the most example of Uzbek classical musical heritage. The art of singing plays considerable role in culture of Uzbek national music. On the basis of classical singing the following singing directions as "Folk singing" (yallachilik), "Classical singing" (mumtoz yallachilik), "Grand Song" (katta ashulachilik) and "Art of Makom" singing forms were formulated and developed. Greatest representatives of Margilan School of singing.展开更多
Based on the construction property of rolled compacted concrete, three-dimensional finite element relocating mesh method was developed in simulating construction process and computing temperature and stress field. Usi...Based on the construction property of rolled compacted concrete, three-dimensional finite element relocating mesh method was developed in simulating construction process and computing temperature and stress field. Using this method, the temperature and the thermal stress fields developed in the RCC gravity dam of the Longtan project with or without a longitudinal joint during construction and operation are calculated so as to simulate the construction process. The computation results show that the value of the thermal stresses developed in the dam even, without any longitudinal joint, could meet the design criteria provided the placement temperature is adequately controlled.展开更多
基金the 13th Five-Year Plan Project of Tianjin Education and Science(HE3078).
文摘With the arrival of the era of big data,the basic research of mathematics has attracted unprecedented attention all over the country.To meet the needs of the development of the times,the construction of mathematics discipline has become one of the important tasks of higher mathematics teaching.Starting from the demand orientation,this paper deeply analyzes the problems existing in mathematics education at the present stage,and constructs the construction path of mathematics discipline based on demand orientation.
文摘Since modern ecology studies the relationships between living things and their environments,the philosophies correlating to it has become optimal preferences in evaluating disputes arising in economic,political,cultural,and even pedagogical fields.The study of this paper proclaims that ecology oriented college English classroom construction in China is conducive to stimulating the classroom vitalities,and ensuring the sustainable development of teaching order.
文摘This paper describes the influence of joint spacing and joint orientation on the penetration rate of a Tunnel Boring Machine (TBM) disc cutter as modeled by the Discrete Element Method (DEM). The input data for the siLmulations were obtained from the sandstone along the AIborz tunnel that is currently being excavated in Iran using a 5.2 m diameter open TBM. Three joint spacings, 150, 200, and 300 mm, were modeled together with seven values of joint orientation; 0°, 15°, 30°, 45°, 60°, 75°, and 90°. The results show that the penetration increases when joint orientation increases from 0° to 75°, but it decreases as the joint orientation increases further from 75° to 90°. This is true for each joint spacing. In addition, for a given joint orientation increasing the joint spacing causes the TBM penetration to decrease. The optimum joint orientation, from the viewpoint of TBM penetration, is about 60-75°.
基金Sponsored by the Natural Science Foundation of Shandong Province of China (Grant No. ZR2019MEE047)the National Key Research and Development Project of China (Grant No. 2020YFB1901403)CSCEC Technical and Development Plan (Grant No. CSCEC-2020-Z-35)。
文摘Modularized construction is a new type of prefabricated building system with green environmental protection and excellent performance. There are few studies on the seismic performance of its key connection joint. This paper presents a new type of assembled connection joint for the high-rise modularized construction. Cyclic shear tests of full-scale joints were carried out, and the key indexes of their seismic performances including the hysteretic performance, ductility, and energy dissipation capacity were analyzed and obtained. The results show that the hysteresis loops of longitudinal and lateral cyclic shear tests were both plump in shapes. The ductility coefficients were 4.54 and 4.98, and the energy dissipation coefficients were 1.83 and 1.43, respectively. The test joint had good ductility and energy dissipation capacity. The positions of yield failure of specimens were mainly concentrated in the connection areas between the column and short beam or end-plate. The research can provide the technical reference for the seismic design and engineering application of related modularized constructions.
文摘On December 20,2016 the construction of the SinoKuwait Guangdong integrated refining/chemical join venture project,which is the largest Sinopec’s projec under construction and also the key construction project of Guangdong province,had been kicked off comprehensively.This project is located in the new district of the East Sea Island inside the Zhanjiang Economic Development
基金funded by the National Natural Science Foundation of China(Grant Nos.41972264 and 52078093)Liaoning Revitalization Talents Program,China(Grant No.XLYC1905015)。
文摘The paper proposes a new multiple-factor clustering method(NMFCM)with consideration of both box fractal dimension(BFD)and orientation of joints.This method assumes that the BFDs of different clusters were uneven,and clustering was performed by redistributing the joints near the boundaries of clusters on a polar map to maximize an index for estimating the difference of the BFD(DBFD).Three main aspects were studied to develop the NMFCM.First,procedures of the NMFCM and reasonableness of assumptions were illustrated.Second,main factors affecting the NMFCM were investigated by numerical simulations with disk joint models.Finally,two different sections of a rock slope were studied to verify the practicability of the NMFCM.The results demonstrated that:(1)The NMFCM was practical and could effectively alleviate the problem of hard boundary during clustering;(2)The DBFD tended to increase after the improvement of clustering accuracy;(3)The improvement degree of the NMFCM clustering accuracy was mainly influenced by three parameters,namely,the number of clusters,number of redistributed joints,and total number of joints;and(4)The accuracy rate of clustering could be effectively improved by the NMFCM.
文摘The new adhesive material for the construction joints of tunnel lining(named as SZC) was studied based on the structural characteristics of interfaces and the characteristic of bonding construction, and the performance indexes were verified by tests. The experimental results show that the adhesive capability of interface is improved effectively by using SZC material, the properties, such as anti-freezing, erosion-resistance and anti-shrinkage are improved greatly as well as durability.
文摘In the Republic of Kazakhstan, the regulatory framework in construction based on Eurocodes has been in force since 2015. However, Kazakhstani produced steel has not been studied for compliance with the requirements of Eurocode 1993. This has resulted in limited use of Kazakhstani structural steel in construction. The feasibility of using structural steel in welded joints has been experimentally investigated. To verify the application of such joints in construction, including earthquake engineering, experimental studies of welded joints made of structural steel produced by Arcelor-Mittal in Temirtau have been carried out. In total, 7 types of structural steel of various thicknesses were selected. Five specimens have been used in each series of tests. The Brinell hardness values of the weld joint, yield strength of steel and tensile strength, relative rupture strain were determined. It was found that for all types of structural steel, the quality of weld joints complied with the requirements of Eurocode 1993—a sample rupture appeared along the plates (main body of the metal), not along the weld joints. It has been established that structural steel produced in the Republic of Kazakhstan fully complies with the requirements of Eurocode 1993. The studies on the dependence of Brinell hardness values of weld joint steel on the yield strength, tensile strength and relative rupture strain have been carried out. The correlation dependences between the values of yield strength of steel and tensile strength, relative rupture strain and BH Brinell hardness were studied. The results of work will allow for significantly increasing the use of Kazakhstani structural steel in seismic and conventional areas of the Republic of Kazakhstan.
文摘On the basis of analyzing cases of existing rural collectively owned profit-oriented construction land entering into trading market,this paper put forward several thoughts,introduced methods and paths for rural collectively owned profit-oriented construction land entering into trading market,including reforming rural collective land property right system,cultivating new rural collective economy organizations,helping them to become market entities; improving various legal systems,making clear range of construction land entering into trading market; formulating scientific benefit allocation mechanism; establishing fair and transparent decision making mechanism.
基金Projects(51621006,51779251)supported by the National Natural Science Foundation of China。
文摘Columnar jointed rock mass with unique geometric and geological properties is one spectacular example of geometrical order in nature.Columnar joints are generally accepted to be formed by spatially uniform volume contraction during cooling.In this paper,substantial field work was performed to study the geological characteristics of irregular columnar jointed basalt on the left bank dam foundation in the Baihetan Hydropower Station,where the columnar jointed rock mass is extensively exposed due to excavation.The quantitative measurements of the sizing of polygonal crack pattern of columnar joints and assessment of their degree of irregularity were summarized.Considering the irregularity of polygonal crack pattern,a modified Voronoi polygon(MVP)method was developed to model the special polygonal crack pattern of columnar joints.The new polygonal pattern obtained by the MVP method consists of a large number of irregular polygons,of which the degree of irregularity is consistent with the field measurement results.This method can reproduce the rapid evolution from an initial ideal regular hexagonal pattern to a final actual irregular polygonal pattern as the degree of irregularity increases.The compression tests of columnar jointed rock mass with different irregularity show that the geometric irregularity has a great influence on its mechanical properties.This numerical construction method provides a reliable way to reconstruct columnar joint structure with specific polygonal crack pattern,which is consistent with onsite columnar jointed basalt.
基金the General Program of the National Natural Science Foundation of China(Grant No.51878037).
文摘Model tests and numerical calculations were adopted based on the New Yuanliangshan tunnel project to investigate the water pressure resistance of lining construction joints in high-pressure and water-rich karst tunnels.A large-scale model test was designed and conducted,innovatively transforming the external water pressure of the lining construction joint into internal water pressure.The effects of the embedded position and waterstop type on the water pressure resistance of the construction joint were analyzed,and the reliability of the model test was verified via numerical calculations.The results show that using waterstops can significantly improve the water pressure resistance of lining construction joints.The water pressure resistance of the lining construction joint is positively correlated with the lining thickness and embedded depth of the waterstop.In addition,the type of waterstop significantly influences the water pressure resistance of lining construction joints.The test results show that the water pressure resistance of the embedded transverse reinforced waterstop is similar to that of the steel plate waterstop,and both have more advantages than the rubber waterstop.The water pressure resistance of the construction joint determined via numerical calculations is similar to the model test results,indicating that the model test results have high accuracy and reliability.This study provides a reference for similar projects and has wide applications.
文摘Background Determination of the proper orientation of the knee articular surface is required both for correction of knee malalignment by osteotomy and for correct component alignment in knee arthroplasty. We sought to determine whether the patients' sex and lower extremity alignment (hip-knee-ankle angle) affects proper knee realignment in osteotomy or component alignment in total knee arthroplasty. Methods We examined 199 healthy adult knees with malalignment of 〈5°to determine the mechanical medial distal femoral angle, mechanical medial proximal tibial angle, surgical transepicondylar axis angle, and discrepancies between bone-cut orientations of osteotomy or total knee arthroplasty and the joint line of the distal femoral condyles, posterior femoral condyles and proximal tibial plateaus, using a three-dimensional computed tomography model. Results The mean mechanical medial distal femoral angle and mean mechanical medial proximal tibial angle were (94.4±1.9)° and (87.6±1.8)° respectively for women and (93.8±2.0)° and (87.1±1.4)° respectively for men. The surgical transepicondylar axis angle was (2.9±1.6)° for women and (3.2±1.7)° for men. Independent of sex, the hip-knee-ankle angle was closely related to the mechanical medial distal femoral angle and mechanical medial proximal tibial angle, but not to the surgical transepicondylar axis angle. A slightly more valgus alignment of the knee and a more valgus angulation of the distal femoral joint line were found in women, whereas a more varus angulation of the proximal tibial joint line was found in men. Sex had the greatest effect on knee joint line orientation when the lower extremity was valgus in alignment. Conclusions A more valgus femoral joint line can be expected in women and in persons with valgus lower extremity aliqnment; a more varus tibial joint line can be found in men and in persons with varus lower extremity alignment.
基金The Cultural Ministry Foundation of China(No.17-2009)the Research Foundation of Palace Museum(No.2007-4)
文摘In order to well protect Chinese ancient buildings, aseismic behaviors of Chinese ancient tenon-mortise joints strengthened by carbon fibre reinforced plastic (CFRP) are studied by experiments. Based on the actual size of an ancient building, a wooden frame model with a scale of 1 : 8 of the prototype structure is built considering the swallow-tail type of tenon-mortise connections. Low cyclic reversed loading tests are carried out including three groups of unstrengthened structures and two groups of structures strengthened with CFRP. Based on experimental data, moment-rotation angle hysteretic curves and skeleton curves for each joint are obtained. The energy dissipation capability, stiffness degradation and deformation performance of the joints before and after being strengthened are also analyzed. Results show that after being strengthened with CFRP, the tenon value pulled out of the mortise is reduced; the bending strength and the energy dissipation capabilities of the joint are enhanced; stiffness degradation of the joint is not obvious; and the deformation performance of the joint remains good. Thus, the CFRP has good effects on strengthening the tenon-mortise joints of Chinese ancient buildings.
基金The authors gratefully acknowledge the following support:National Key R&D Program(No.2018YFC0705400)National Natural Science Foundation of China(Grant No.51778223)+1 种基金Major Program of Science and Technology of Hunan Province(No.2017SK1010)The authors also express their sincere appreciation to the reviewers of this paper for their constructive comments and suggestions.
文摘In this study,a fully precast steel—ultrahigh performance concrete(UHPC)lightweight composite bridge(LWCB)was proposed based on Mapu Bridge,aiming at accelerating construction in bridge engineering.Cast-in-place joints are generally the controlling factor of segmental structures.Therefore,an innovative girder-to-girder joint that is suitable for LWCB was developed.A specimen consisting of two prefabricated steel—UHPC composite girder parts and one post-cast joint part was fabricated to determine if the joint can effectively transfer load between girders.The flexural behavior of the specimen under a negative bending moment was explored.Finite element analyses of Mapu Bridge showed that the nominal stress of critical sections could meet the required stress,indicating that the design is reasonable.The fatigue performance of the UHPC deck was assessed based on past research,and results revealed that the fatigue performance could meet the design requirements.Based on the test results,a crack width prediction method for the joint interface,a simplified calculation method for the design moment,and a deflection calculation method for the steel—UHPC composite girder in consideration of the UHPC tensile stiffness effect were presented.Good agreements were achieved between the predicted values and test results.
文摘This study was undertaken to determine the bending strength properties of off-cut Yellow Meranti wood by applying the finger jointed techniques. The finger orientations that were used in this study are vertical and horizontal finger orientation. Specimens were bonded with PVAc (polyvinyl acetate). The bending strength properties were determined by the three point and four point bending test method. The results show that vertical finger orientation has the higher mean of modulus of rupture and the modulus of elasticity value of 24.49 MPa (28.91 MPa) and 8,814 MPa (11,668 MPa) respectively. However, the tested specimen properties did not meet the minimum strength of the solid (control) specimens.
基金Supported by the National High Technology Research and Development Program of China(863 Program)(2012AA012902)
文摘Automatic return oriented programming (ROP) technology can effectively improve the efficiency of ROP constructed, but the existing research results still have some shortcomings including needing more address space, poor generality. In order to solve these problems, this paper presents an improved ROP auto-constructor QExtd. Firstly, we design a Turing-complete language QExtdL and provide the basis of gadgets analysis. Secondly, we represent the MI instruction and realize precise process of side-effect instructions for improving the efficiency of automatic construction. At last, we establish a three-layer language conversion mechanism, making it convenient for users to construct ROP. Theoretical and experimental data show that the QExtd automatic construction method is much better than the ROPgadget based on syntax. In addition, the proposed method succeeds in constructing gadgets of ROP with the probability of 84% for programs whose sizes are more than 20 KB and whose directory is "/usr/bin" in Ubuntu, which proves that the construction capability improves significantly.
文摘1 Project positioning Baihetan Hydropower Station is classified as the second of the four hydropower cascades in the lower reaches of the Jinsha River:Wudongde,Baihetan,Xiluodu and Xiangjiaba.As an important backbone project for China to implement the strategy of West-to-East Power Transmission and optimize the energy structure,it constitutes an important part of the Yangtze River flood control system.Located at the junction of Ningnan County,Sichuan Province and Qiaojia County,Yunnan Province,the hydropower station is the largest hydropower project under construction in the world,with a unit capacity of million-kilowatts ranking the highest in the world and a total installed capacity of 16 million kW,second only to the Three Gorges Project,ranking the second in the world.
文摘The article deals with musical heritage of some Orient cultures, joint singing as one of the main part of music art from ancient time to nowadays. The measure reflecting live process of national musical art is a performing practice. Makom is the most example of Uzbek classical musical heritage. The art of singing plays considerable role in culture of Uzbek national music. On the basis of classical singing the following singing directions as "Folk singing" (yallachilik), "Classical singing" (mumtoz yallachilik), "Grand Song" (katta ashulachilik) and "Art of Makom" singing forms were formulated and developed. Greatest representatives of Margilan School of singing.
文摘Based on the construction property of rolled compacted concrete, three-dimensional finite element relocating mesh method was developed in simulating construction process and computing temperature and stress field. Using this method, the temperature and the thermal stress fields developed in the RCC gravity dam of the Longtan project with or without a longitudinal joint during construction and operation are calculated so as to simulate the construction process. The computation results show that the value of the thermal stresses developed in the dam even, without any longitudinal joint, could meet the design criteria provided the placement temperature is adequately controlled.