We calculated the mechanical properties, electronic structure, theoretical hardness and optical properties of V4AlC3 using the first-principles method. The results show that V4AlC3 shows a better performance of the resistance to shape change and against uniaxial tensions and has a slight anisotropy on elasticity. Moreover, it is more brittle than α-Nb4AlC3 and Ta4AlC3. The chemical bonding of V4AlC3 is a combination of covalent, ionic and metallic nature. The calculated theoretical hardness is 9.33 GPa, and the weaker covalent bonding of Al–V is responsible for the low hardness of V4AlC3. The optical properties (dielectric function, absorption spectrum, conductivity, energy-loss spectrum and reflectivity) are discussed in detail. It is shown that V4AlC3 has the potential to be used as a promising dielectric material and coating to avoid solar heating.

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Fabric anisotropy has a significant influence on the mechanical behavior of sand. An anisotropic plasticity model incorporating fabric evolution is formulated in this study. Information on the overall stress–strain relationship and micromechanical fabric states from DEM numerical tests is used in the development of the constitutive model, overcoming the difficulties of fabric measurement in physical tests. The framework of the model and its formulations for fabric evolution, plasticity, and dilatancy enables it to capture the strength, shear modulus, and dilatancy of sand under both monotonic and cyclic loading. The model is validated against DEM numerical tests and physical laboratory tests on samples with different initial fabric, showing good agreement between the simulation and test results for the anisotropic stress–strain behavior of sand. The use of DEM test data also allows for the validation of the model on the micromechanical fabric level, showing that the model can reproduce the fabric evolution and its influence on key constitutive features reasonably well. The model is further applied to analyze the liquefaction behavior of sand, exhibiting the significant influence of fabric anisotropy on both liquefaction resistance and postliquefaction shear deformation.

We present a novel approach for improving the shape statistics of medical image objects by generating correspondence of skeletal points. Each object’s interior is modeled by an s-rep, i.e., by a sampled, folded, 2-sided skeletal sheet with spoke vectors proceeding from the skeletal sheet to the boundary. The skeleton is divided into three parts: the up side, the down side and the fold curve. The spokes on each part are treated separately and, using spoke interpolation, are shifted along that skeleton in each training sample so as to tighten the probability distribution on those spokes’ geometric properties while sampling the object interior regularly. As with the surface/boundary-based correspondence method of Cates et al., entropy is used to measure both the probability distribution tightness and sampling regularity, here of the spokes’ geometric properties. Evaluation on synthetic and real world lateral ventricle and hippocampus datasets demonstrate improvement in the performance of statistics using the resulting probability distributions. This improvement is greater than that achieved by an entropy-based correspondence method on the boundary points.

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With the rapid development of cloud storage, an increasing number of users store their images in the cloud. These images contain many business secrets or personal information, such as engineering design drawings and commercial contracts. Thus, users encrypt images before they are uploaded. However, cloud servers have to hide secret data in encrypted images to enable the retrieval and verification of massive encrypted images. To ensure that both the secret data and the original images can be extracted and recovered losslessly, researchers have proposed a method that is known as reversible data hiding in encrypted images (RDHEI). In this paper, a new RDHEI method using median edge detector (MED) and two’s complement is proposed. The MED prediction method is used to generate the predicted values of the original pixels and calculate the prediction errors. The adaptive-length two’s complement is used to encode the most prediction errors. To reserve room, the two’s complement is labeled in the pixels. To record the unlabeled pixels, a label map is generated and embedded into the image. After the image has been encrypted, it can be embedded with the data. The experimental results indicate that the proposed method can reach an average embedding rate of 2.58 bpp, 3.04 bpp, and 2.94 bpp on the three datasets, i.e., UCID, BOSSbase, BOWS-2, which outperforms the previous work.

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This paper focuses on the problem of reliable H ∞ control for a class of switched nonlinear systems with actuator failures among a prespecified subset of actuators. In existing works, the reliable H ∞ design methods are all based on a basic assumption that the never failed actuators must stabilize the given system. But when actuators suffer "serious failure"-the never failed actuators can not stabilize the given system, the standard design methods of reliable H ∞ control do not work. Based on the switching technique, the problem can be solved by means of switching among subsystems or finite candidate controllers.Copyright c 2005 IFAC