As cloud computing is becoming prevalent, data owners are motivated to delegate complex data managements to the commercial cloud for economic savings. Sensitive data is usually encrypted before being uploaded to the c...As cloud computing is becoming prevalent, data owners are motivated to delegate complex data managements to the commercial cloud for economic savings. Sensitive data is usually encrypted before being uploaded to the cloud, which unfortunately makes the frequently-used search function a challenging problem. In this paper, we present a new multi-keyword dynamic search scheme with result ranking to make search over encrypted data more secure and practical. In the scheme, we employ a powerful function-hiding inner product encryption to enhance the security by preventing the leakage of search pattern. For the concern of efficiency, we adopt a tree-based index structure to facilitate the searching process and updating operations. A comprehensive security analysis is provided and experiments over the real world data show that our scheme is efficient.展开更多
Direct perfusion of three-dimensional cell-seeded biological scaffolds is known to enhance osteogenesis, which can be partly attributed to mechanical stimuli affecting cell proliferation and differentiation in the pro...Direct perfusion of three-dimensional cell-seeded biological scaffolds is known to enhance osteogenesis, which can be partly attributed to mechanical stimuli affecting cell proliferation and differentiation in the process of bone tissue regeneration. This study aimed to compare the hydrodynamic environment, including the distributions of fluid flow velocity, wall shear stress and pressure in pores filled with liquid, designed scaffold(DS), porous and biodegradable β-TCP(β-tricalcium phosphate) based on freeze-drying scaffold(FS) and dog’s femora scaffold(NS). Gravity condition, inlet velocities of 1, 10, 100 and 1000 μm/s and medium viscosities of 1.003, 1.45 and 2.1 m Pas were applied as the initial conditions. With an inlet fluid velocity of 100 m/s and a viscosity of 1.45(10-3Pas, the simulation results of maximal and average wall shear stress were 15.675 m Pas and 3.223 m Pas for DS, 67.126 m Pas and5.949 m Pas for FS, and 20.190 m Pas and 1.629 m Pas for NS. Variations of inlet fluid velocity and fluid viscosity produced corresponding proportional changes in fluid flow velocity, wall shear stress and pressure. DS and FS were evaluated in terms of simulation results and microstructure using NS as a reference standard. This methodology allows a greater insight into the complex concept of tissue engineering and will likely help in understanding and eventually improving the fluid-mechanical aspects.展开更多
基金supported in part by the National Natural Science Foundation of China (61272481, 61572460, 61402352)the National Key Research and Development Project (2016YFB0800703)+2 种基金the National Information Security Special Projects of National Developmentthe Reform Commission of China [(2012)1424]China 111 Project (No. B16037)
文摘As cloud computing is becoming prevalent, data owners are motivated to delegate complex data managements to the commercial cloud for economic savings. Sensitive data is usually encrypted before being uploaded to the cloud, which unfortunately makes the frequently-used search function a challenging problem. In this paper, we present a new multi-keyword dynamic search scheme with result ranking to make search over encrypted data more secure and practical. In the scheme, we employ a powerful function-hiding inner product encryption to enhance the security by preventing the leakage of search pattern. For the concern of efficiency, we adopt a tree-based index structure to facilitate the searching process and updating operations. A comprehensive security analysis is provided and experiments over the real world data show that our scheme is efficient.
基金supported by National Natural Science Foundation of China(No.81201386)the Shanghai Key Laboratory of Manufacturing Automation and Robotics(No.ZK1103)
文摘Direct perfusion of three-dimensional cell-seeded biological scaffolds is known to enhance osteogenesis, which can be partly attributed to mechanical stimuli affecting cell proliferation and differentiation in the process of bone tissue regeneration. This study aimed to compare the hydrodynamic environment, including the distributions of fluid flow velocity, wall shear stress and pressure in pores filled with liquid, designed scaffold(DS), porous and biodegradable β-TCP(β-tricalcium phosphate) based on freeze-drying scaffold(FS) and dog’s femora scaffold(NS). Gravity condition, inlet velocities of 1, 10, 100 and 1000 μm/s and medium viscosities of 1.003, 1.45 and 2.1 m Pas were applied as the initial conditions. With an inlet fluid velocity of 100 m/s and a viscosity of 1.45(10-3Pas, the simulation results of maximal and average wall shear stress were 15.675 m Pas and 3.223 m Pas for DS, 67.126 m Pas and5.949 m Pas for FS, and 20.190 m Pas and 1.629 m Pas for NS. Variations of inlet fluid velocity and fluid viscosity produced corresponding proportional changes in fluid flow velocity, wall shear stress and pressure. DS and FS were evaluated in terms of simulation results and microstructure using NS as a reference standard. This methodology allows a greater insight into the complex concept of tissue engineering and will likely help in understanding and eventually improving the fluid-mechanical aspects.
