Synthesis and thermodynamic analysis of nano-La2O3

The thermodynamic parameters of La(NO₃)₃ and La(OH)₃ are evaluated and the thermodynamics of nano-La₂O₃ synthetic process is analyzed. On the base of thermodynamic analysis, La₂O₃ nano-powders are prepared by the sol-gel method and the experiment scheme is designed by an orthogonal method. The dry-gelatin is analyzed with differential thermal analysis/thermo-gravimetric analysis (TGA-DTA) and X-ray diffraction method. The microstructure of nano-La₂O₃ powders is observed by transmission electron microscope. The synthetic parameters affecting the average grain size and dispersivity of nano-La₂O₃ particles are experimentally examined and analyzed. All the results indicate that nano-La₂O₃ particles well-dispersed are obtained and the average grain size is in the range of 20—50 nm.     

Attribute-Based Encryption for Circuits on Lattices

In the previous construction of attributed-based encryption for circuits on lattices, the secret key size was exponential to the number of AND gates of the circuit. Therefore, it was suitable for the shallow circuits whose depth is bounded. For decreasing the key size of previous scheme, combining the techniques of Two-to-One Recoding （TOR）, and sampling on lattices, we propose a new Key-Policy Attribute-Based Encryption （KP-ABE） scheme for circuits of any arbitrary polynomial on lattices, and prove that the scheme is secure against chosen plaintext attack in the selective model under the Learning With Errors （LWE） assumptions. In our scheme, the key size is proportional to the number of gates or wires in the circuits.     

Rare earth effect of yttrium on formation and property of Cr2O3 oxide film formed on Co-Cr binary alloy

The isothermal oxidizing kinetics of Co-40Cr alloy and its yttrium ion?implanted samples were studied at 1000 ℃ in air by thermal?gravity analysis (TGA). Scanning electronic microscopy (SEM) was used to examine the Cr2O₃ oxide film's morphology after oxidation. Secondary ion mass spectrum (SIMS) method was used to examine the binding energy change of chromium caused by Y?doping and its influence on formation of Cr2O₃ film. Acoustic emission (AE) method was used in situ to monitor the cracking and spalling of oxide films formed on both samples during oxidizing and subsequent air?cooling stages. Theoretical model simulating the film fracture process was proposed to analyze the acoustic emission spectrum both on time domain and on AE?event number domain. It is found that yttrium ion?implantation can remarkably reduce the isothermal oxidizing rate of Co-40Cr and improve the anti?cracking and anti?spalling properties of Cr2O₃ oxide film. Reasons for the improvement are mainly that the implanted yttrium can reduce the grain size of Cr2O₃ oxide, increase the high temperature plasticity of oxide film, and remarkably reduce the number and size of Cr2O₃/Co-40Cr interfacial defects.     

Rare earth effect of yttrium on formation and property of Cr2O3 oxide film formed on Co-Cr binary alloy

The isothermal oxidizing kinetics of Co-40Cr alloy and its yttrium ion?implanted samples were studied at 1000 ℃ in air by thermal?gravity analysis (TGA). Scanning electronic microscopy (SEM) was used to examine the Cr2O₃ oxide film's morphology after oxidation. Secondary ion mass spectrum (SIMS) method was used to examine the binding energy change of chromium caused by Y?doping and its influence on formation of Cr2O₃ film. Acoustic emission (AE) method was used in situ to monitor the cracking and spalling of oxide films formed on both samples during oxidizing and subsequent air?cooling stages. Theoretical model simulating the film fracture process was proposed to analyze the acoustic emission spectrum both on time domain and on AE?event number domain. It is found that yttrium ion?implantation can remarkably reduce the isothermal oxidizing rate of Co-40Cr and improve the anti?cracking and anti?spalling properties of Cr2O₃ oxide film. Reasons for the improvement are mainly that the implanted yttrium can reduce the grain size of Cr2O₃ oxide, increase the high temperature plasticity of oxide film, and remarkably reduce the number and size of Cr2O₃/Co-40Cr interfacial defects.     

热处理对CaO-Al2O3-SiO2系烧结微晶玻璃吸水率的影响

By means of measuring the changes of the water absorbance of glass particles in sintering with different starting size and the observation by scanning electron microscopy, the effect of heat treatment on the water absorbance of CaO-Al₂O₃-SiO₂ sintered glass-ceramics was studied in order to decrease the water absorbance of glass-ceramics. Results show that the glass-ceramics has higher water absorbance while sintering at lower temperature (900　℃). The water absorbance decreases greatly as temperature goes up. However, it increases slightly during longer stay at higher temperature (1　050～1　100　℃). The starting particle size of the glass has minor effect on the water absorbance of glass-ceramics sintering at higher temperature.     

A hierarchical attribute-based encryption scheme

According to the relation of an attribute set and its subset,the author presents a hierarchical attribute-based encryption scheme in which a secret key is associated with an attribute set.A user can delegate the private key corresponding to any subset of an attribute set while he has the private key corresponding to the attribute set.Moreover,the size of the ciphertext is constant,but the size of private key is linear with the order of the attribute set in the hierarchical attribute-based encryption scheme.Lastly,we can also prove that this encryption scheme meets the security of IND-sSETCPA in the standard model.     

Effect of CH3OOH on the atmospheric concentration of OH radicals

Methyl hydroperoxide (CH₃OOH, MHP) is known to be a significant sink and reservoir of HO_x and RO_x radicals in the atmosphere. In order to investigate the impact of MHP on the concentration of atmospheric OH radicals, two key gas-phase reactions of MHP, i.e. the reactions with OH radicals and with UV photolysis, have been simulated at temperature of 293±2 K and total pressure of 1.01×10⁵ Pa, using the long path Fourier transform infrared (LP-FTIR) spectrometry. OH radicals are generated by the photolysis of O₃ in the presence of water vapor. Combined with the relative rate method, the reaction rate constant of MHP with OH radicals is determined to be (3.99±0.15)×10^-12 cm³?molecule^-1?s^-1, and thus the atmospheric lifetime of MHP is estimated at 2.9 days. Furthermore, from detailed analysis of the UV photolysis of MHP, the yield of OH radicals is obtained to be 0.91±0.04. Based on the MHP atmospheric lifetime and the yield of OH radicals, it is concluded that MHP plays an essential role in the redistribution of OH radicals in the troposphere.     

Effect of CH3OOH on the atmospheric concentration of OH radicals

Methyl hydroperoxide (CH₃OOH, MHP) is known to be a significant sink and reservoir of HO_x and RO_x radicals in the atmosphere. In order to investigate the impact of MHP on the concentration of atmospheric OH radicals, two key gas-phase reactions of MHP, i.e. the reactions with OH radicals and with UV photolysis, have been simulated at temperature of 293±2 K and total pressure of 1.01×10⁵ Pa, using the long path Fourier transform infrared (LP-FTIR) spectrometry. OH radicals are generated by the photolysis of O₃ in the presence of water vapor. Combined with the relative rate method, the reaction rate constant of MHP with OH radicals is determined to be (3.99±0.15)×10^-12 cm³?molecule^-1?s^-1, and thus the atmospheric lifetime of MHP is estimated at 2.9 days. Furthermore, from detailed analysis of the UV photolysis of MHP, the yield of OH radicals is obtained to be 0.91±0.04. Based on the MHP atmospheric lifetime and the yield of OH radicals, it is concluded that MHP plays an essential role in the redistribution of OH radicals in the troposphere.     

Optimization in the Migration Problem of Mobile Agents in Distributed Information Retrieval Systems

In this paper,we employ genetic algorithms to solve the migration problem (MP).We propose a new encoding scheme to represent trees,which is composed of two parts;the pre-ordered traversal sequence of tree vertices and the children number sequence of corresponding tree vertices.The proposed encoding scheme has the advantages of simplicity for encoding and decoding,ease for GA operations,and better equilibrium between exploration and exploitation.It is also adaptive in that,with few restrictions on the length of code,it can be freely lengthened or shortened according to the characteristics of the problem space.Furthermore,the encoding scheme is highly applicable to the degreeconstrained minimum spanning tree problem because it also contains the degree information of each node.The simulation results demonstrate the higher performance of our algorithm,with fast convergence to the optima or sub-optima on various problem sizes.Comparing with the binary string encoding of vertices,when the problem size is large,our algorithm runs remarkably faster with comparable search capability.     

A Fast Algorithm for GVF Snake Model

A research on difference scheme of image gravitational field in the GVF snake model is performed depending on the uniform stability and convergence conditions of the difference scheme.It is found that the original explicit forward difference scheme puts a strict restriction on the diffusion coefficient in the partial differential equation which decelerates the convergence speed of difference equation iteration.A new difference scheme is put forward,which has the advantage of unconditional uniform stability and convergence,and the restriction on the coefficient of partial differential equation is removed.Through increasing the value of the coefficient appropriately,the image of boundary information transmission becomes faster.Hence,iteration calculations are decreased rapidly for a given transmission range.The simulation experiments indicate that the new difference scheme be higher efficiency than the traditional one.