Objective To investigate the clinical outcomes of trans-facet joints approach to treat thoracic degenerative disease with anterior compression.Methods From January 2003 to December 2009,22 patients with thoracic myelo...Objective To investigate the clinical outcomes of trans-facet joints approach to treat thoracic degenerative disease with anterior compression.Methods From January 2003 to December 2009,22 patients with thoracic myelopathy caused by展开更多
The determination of discontinuity shear strength is an important concern in rock engineering.Previous research mainly focused on the shear behavior of discontinuities with identical joint wall compressive strengths(D...The determination of discontinuity shear strength is an important concern in rock engineering.Previous research mainly focused on the shear behavior of discontinuities with identical joint wall compressive strengths(DIJCS).However,the shear behavior of discontinuities with different joint wall compressive strengths(DDJCS)and 3D surface morphology had been rarely reported.In this study,matched mortar DDJCSs were prepared using 3D printed photosensitive resin molds.Direct shear tests were carried out under three kinds of normal stress(ranging from 0.5 to 3.0 MPa)to analyze the shear strength and contact zones of DDJCS during shearing.The results show that the contact zones of DDJCS during shearing are scattered in the steep zones facing the shear direction.It is verified that Grasselli and Develi’s directional surface roughness characterization method can be used to predict the shear-induced potential contact zones of DDJCS.When the critical apparent dip angle is equal to the peak dilation angle,the predicted contact area agrees well with the actual contact area.A 3D directional roughness parameter with clear physical meaning was introduced to characterize discontinuity surface roughness.A 3D modified joint roughness coefficient-joint wall compressive strength(JRC-JCS)criterion that can both predict the shear strength of DDJCS and DIJCS was proposed based on the newly defined roughness parameter.The proposed criterion was validated by 77 direct shear tests presented by this study and 163 direct shear tests presented by other investigators.The results show that the proposed criterion was generally reliable for the peak shear strength prediction of DDJCS and DIJCS(within 16%).It is also found that the new criterion can capture the anisotropy of the peak shear strength of DDJCS.The anisotropy of DDJCS decreases with increasing normal stress.It should be noted that the anisotropy of the shear strength of DDJCS was not investigated experimentally,and further experiments should be conducted to verify it.展开更多
Since the welded constructions produce easily stress corrosion cracking (SCC) or fatigue disruption in corrosive medium or under ripple load, two methods inducing compressive stress on structural surfaces by anti-weld...Since the welded constructions produce easily stress corrosion cracking (SCC) or fatigue disruption in corrosive medium or under ripple load, two methods inducing compressive stress on structural surfaces by anti-welding-heating treatment (AWHT) and explosion treatment (ET) are presented. The results show that they are good ways to resisting SCC on the welded SS400 steel or other components.展开更多
The growing demand for geothermal energy exploration and deep engineering projects necessitates a deeper understanding of rock behavior under extreme thermal conditions.This study investigates the effect of thermal tr...The growing demand for geothermal energy exploration and deep engineering projects necessitates a deeper understanding of rock behavior under extreme thermal conditions.This study investigates the effect of thermal treatment on the shear behavior of sedimentary sandstone and igneous granite,which are abundant in the Earth's crust.Direct shear tests were conducted on rock joints at room temperature(RT),250℃,and 500℃.The results show that the joints in sandstone and granite exhibit improved compressive and shear strength up to a temperature threshold of 200℃–350℃,followed by significant weakening beyond this range.This study investigated key parameters,including normal and shear stiffness,maximum joint closure,peak and residual shear strengths,internal friction angle,dilation angle,and cohesion.The compressive behavior of both rock types followed a modifiedBandis's equation.The peak shear strength followed Patton's bilinear and Jaeger's nonlinear failure criteria more accurately than the Mohr–Coulomb criterion.The results of this study provide valuable insights into the temperature-dependent behavior of sandstone and granite joints under compressive and shear loads,and their interoperation was strongly dependent on the mineralogical and structural components of the two rock types.These results have advanced our understanding of the temperature-dependent behavior of rock fractures,improving the safety of underground structures under thermal effects.展开更多
A chaos-based cryptosystem for fractal image coding is proposed. The Renyi chaotic map is employed to determine the order of processing the range blocks and to generate the keystream for masking the encoded sequence. ...A chaos-based cryptosystem for fractal image coding is proposed. The Renyi chaotic map is employed to determine the order of processing the range blocks and to generate the keystream for masking the encoded sequence. Compared with the standard approach of fraetal image coding followed by the Advanced Encryption Standard, our scheme offers a higher sensitivity to both plaintext and ciphertext at a comparable operating efficiency. The keystream generated by the Renyi chaotic map passes the randomness tests set by the United States National Institute of Standards and Technology, and so the proposed scheme is sensitive to the key.展开更多
The compressive sensing （CS） theory allows people to obtain signal in the frequency much lower than the requested one of sampling theorem. Because the theory is based on the assumption of that the location of sparse...The compressive sensing （CS） theory allows people to obtain signal in the frequency much lower than the requested one of sampling theorem. Because the theory is based on the assumption of that the location of sparse values is unknown, it has many constraints in practical applications. In fact, in many cases such as image processing, the location of sparse values is knowable, and CS can degrade to a linear process. In order to take full advantage of the visual information of images, this paper proposes the concept of dimensionality reduction transform matrix and then se- lects sparse values by constructing an accuracy control matrix, so on this basis, a degradation algorithm is designed that the signal can be obtained by the measurements as many as sparse values and reconstructed through a linear process. In comparison with similar methods, the degradation algorithm is effective in reducing the number of sensors and improving operational efficiency. The algorithm is also used to achieve the CS process with the same amount of data as joint photographic exports group （JPEG） compression and acquires the same display effect.展开更多
文摘Objective To investigate the clinical outcomes of trans-facet joints approach to treat thoracic degenerative disease with anterior compression.Methods From January 2003 to December 2009,22 patients with thoracic myelopathy caused by
基金Project(GZB202405561)supported by the China Postdoctoral Fellowship ProgramProject(42377154)supported by the National Natural Science Foundation of China。
文摘The determination of discontinuity shear strength is an important concern in rock engineering.Previous research mainly focused on the shear behavior of discontinuities with identical joint wall compressive strengths(DIJCS).However,the shear behavior of discontinuities with different joint wall compressive strengths(DDJCS)and 3D surface morphology had been rarely reported.In this study,matched mortar DDJCSs were prepared using 3D printed photosensitive resin molds.Direct shear tests were carried out under three kinds of normal stress(ranging from 0.5 to 3.0 MPa)to analyze the shear strength and contact zones of DDJCS during shearing.The results show that the contact zones of DDJCS during shearing are scattered in the steep zones facing the shear direction.It is verified that Grasselli and Develi’s directional surface roughness characterization method can be used to predict the shear-induced potential contact zones of DDJCS.When the critical apparent dip angle is equal to the peak dilation angle,the predicted contact area agrees well with the actual contact area.A 3D directional roughness parameter with clear physical meaning was introduced to characterize discontinuity surface roughness.A 3D modified joint roughness coefficient-joint wall compressive strength(JRC-JCS)criterion that can both predict the shear strength of DDJCS and DIJCS was proposed based on the newly defined roughness parameter.The proposed criterion was validated by 77 direct shear tests presented by this study and 163 direct shear tests presented by other investigators.The results show that the proposed criterion was generally reliable for the peak shear strength prediction of DDJCS and DIJCS(within 16%).It is also found that the new criterion can capture the anisotropy of the peak shear strength of DDJCS.The anisotropy of DDJCS decreases with increasing normal stress.It should be noted that the anisotropy of the shear strength of DDJCS was not investigated experimentally,and further experiments should be conducted to verify it.
文摘Since the welded constructions produce easily stress corrosion cracking (SCC) or fatigue disruption in corrosive medium or under ripple load, two methods inducing compressive stress on structural surfaces by anti-welding-heating treatment (AWHT) and explosion treatment (ET) are presented. The results show that they are good ways to resisting SCC on the welded SS400 steel or other components.
基金the ORSP at Abu Dhabi University,UAE,for funding this project(Grant No.19300751).
文摘The growing demand for geothermal energy exploration and deep engineering projects necessitates a deeper understanding of rock behavior under extreme thermal conditions.This study investigates the effect of thermal treatment on the shear behavior of sedimentary sandstone and igneous granite,which are abundant in the Earth's crust.Direct shear tests were conducted on rock joints at room temperature(RT),250℃,and 500℃.The results show that the joints in sandstone and granite exhibit improved compressive and shear strength up to a temperature threshold of 200℃–350℃,followed by significant weakening beyond this range.This study investigated key parameters,including normal and shear stiffness,maximum joint closure,peak and residual shear strengths,internal friction angle,dilation angle,and cohesion.The compressive behavior of both rock types followed a modifiedBandis's equation.The peak shear strength followed Patton's bilinear and Jaeger's nonlinear failure criteria more accurately than the Mohr–Coulomb criterion.The results of this study provide valuable insights into the temperature-dependent behavior of sandstone and granite joints under compressive and shear loads,and their interoperation was strongly dependent on the mineralogical and structural components of the two rock types.These results have advanced our understanding of the temperature-dependent behavior of rock fractures,improving the safety of underground structures under thermal effects.
基金Project supported by the Research Grants Council of the Hong Kong Special Administrative Region,China(Grant No.CityU123009)
文摘A chaos-based cryptosystem for fractal image coding is proposed. The Renyi chaotic map is employed to determine the order of processing the range blocks and to generate the keystream for masking the encoded sequence. Compared with the standard approach of fraetal image coding followed by the Advanced Encryption Standard, our scheme offers a higher sensitivity to both plaintext and ciphertext at a comparable operating efficiency. The keystream generated by the Renyi chaotic map passes the randomness tests set by the United States National Institute of Standards and Technology, and so the proposed scheme is sensitive to the key.
基金supported by the National Natural Science Foundation of China (61077079)the Specialized Research Fund for the Doctoral Program of Higher Education (20102304110013)the Program Ex-cellent Academic Leaders of Harbin (2009RFXXG034)
文摘The compressive sensing （CS） theory allows people to obtain signal in the frequency much lower than the requested one of sampling theorem. Because the theory is based on the assumption of that the location of sparse values is unknown, it has many constraints in practical applications. In fact, in many cases such as image processing, the location of sparse values is knowable, and CS can degrade to a linear process. In order to take full advantage of the visual information of images, this paper proposes the concept of dimensionality reduction transform matrix and then se- lects sparse values by constructing an accuracy control matrix, so on this basis, a degradation algorithm is designed that the signal can be obtained by the measurements as many as sparse values and reconstructed through a linear process. In comparison with similar methods, the degradation algorithm is effective in reducing the number of sensors and improving operational efficiency. The algorithm is also used to achieve the CS process with the same amount of data as joint photographic exports group （JPEG） compression and acquires the same display effect.
