一种基于卷积码的小波域音频水印盲检算法*

水印系统的顽健性是数字水印研究者最为关注的问题。借助卷积码的编解码思想, 在小波域研究了自适应于音频的扩频水印算法, 将视觉可辨的水印经过预处理后嵌在所选的中、低频小波子带。为了提高算法的顽健性, 提出了适合Viterbi 软解码的水印检测改进算法, 水印检测不需要原始音频。实验结果表明, 基于卷积码的音频扩频水印算法具有很高的顽健性, 能完全抵制信号处理型攻击。     

考虑组件复制的SA软件部署可靠性研究

复制软件组件能提高服务的可靠性和系统可靠性,然而,复制额外的软件组件需要消耗系统可用系统资源.为了充分利用系统可用资源,得到更高的可靠性优化值,设计了启发式的贪婪复制算法,该算法根据单位带宽的可靠性优化值增量OB和单位内存的可靠性优化值增量OM,利用贪婪思想选择出将被复制的两个软件组件集合,其中具有更高可靠性优化值的集合是该算法确定的将被复制的软件组件集合.实验结果表明:当给定有限的系统可用资源时,与贪婪复制算法相比,该算法能得到更高的可靠性优化值和更高的服务可靠性.     

SiCp/Al复合材料三维表面粗糙度信息提取方法

为研究SiCp/Al复合材料三维表面粗糙度信息的提取方法,进行高速铣削实验,并利用OLS3000激光共聚焦扫描显微镜对表面微观轮廓进行非接触式测量.采用最小二乘法、高斯滤波法和扩展高斯滤波法针对已加工表面进行三维粗糙度信息的提取,并计算三维粗糙度参数,从受缺陷的影响程度以及稳定性两方面对3种方法的信息提取效果进行对比.结果表明:高斯滤波法和扩展的高斯滤波法对缺陷的敏感程度较高,且提取出的信息稳定性不好;最小二乘法能很好保留缺陷的信息并具有较高的稳定性,更适合对颗粒增强型铝基复合材料进行三维表面粗糙度信息的提取.     

3D Model Retrieval Method Based on Affinity Propagation Clustering

In order to improve the accuracy and efficiency of 3D model retrieval, the method based on affinity propagation clustering algorithm is proposed. Firstly, projection ray-based method is proposed to improve the feature extraction efficiency of 3D models. Based on the relationship between model and its projection, the intersection in 3D space is transformed into intersection in 2D space, which reduces the number of intersection and improves the efficiency of the extraction algorithm. In feature extraction, multi-layer spheres method is analyzed. The two-layer spheres method makes the feature vector more accurate and improves retrieval precision. Secondly, Semi-supervised Affinity Propagation (S-AP) clustering is utilized because it can be applied to different cluster structures. The S-AP algorithm is adopted to find the center models and then the center model collection is built. During retrieval process, the collection is utilized to classify the query model into corresponding model base and then the most similar model is retrieved in the model base. Finally, 75 sample models from Princeton library are selected to do the experiment and then 36 models are used for retrieval test. The results validate that the proposed method outperforms the original method and the retrieval precision and recall ratios are improved effectively.     

Analysis and Control of Novel Deflection-Type PM Multi-DOF Actuator

This paper mainly presents a PM multi-DOF actuator for robot in-wheels drive applications and its control method. The torque model is established based on the finite-element model of the single pair poles in 3D finite element method software. Due to the special structure of the actuator, the Euler angles are adopted for deriving the kinematics and dynamic model. To reduce the effects of uncertainties of modeling error, nonlinear friction and external disturbances in the system, an approximation of neural network adaptive control method is applied to the actuator. The computation and simulation results show that the proposed analysis and control method can effectively derive the characteristics and improve the motion performance, which provides the primary theoretical guide for the configuration design, optimization and control research of multi-DOF deflection type actuators.     

Impact Dynamics of Supercavitating Projectile with Fluid/Structure Interaction

As supercavitating projectiles move at high speed, the periodic impacts ("tail-slap") on the interior surface of the cavity generally occur due to disturbances. The interactions between the projectile and the water/cavity interface are the sources of structural vibrations, which affect the guidance of the vehicle and undermine the structural reliability. The Fluid/Structure Interaction calculation procedure of the tail-slaps of supercavitating projectile is established, and the dynamic behaviours of the projectile operating in tail-slap conditions with and without considering Fluid/Structure Interaction are obtained and compared. The responses of the projectile riding a reducing cavity are studied, and the effect of Fluid/Structure Interaction is also analyzed. The results show that the angular velocity of projectile increases as the body slowing down, and the amplitude of the elastic displacement response decreases at the beginning and increases when the cavity size is close to the diameter of the tail of projectile. The effect of Fluid/Structure Interaction reduces the amplitudes and frequencies of the impact loads and the vibration responses of the body, and when the speed is higher, the effect is more apparent.     

Research on Ant Colony Algorithm in Vehicle Operation Adjustment Based on IOT

Automatic solution of vehicle operation adjustment is the important content in realizing vehicle traffic command automation on Internet of Things platform. Based on both the organization realization of Internet of Things platform and the merging vehicle operation adjustment into the Flow-Shop scheduling problem in manufacturing systems, this paper has constructed the optimization model with a two-lane vehicle operation adjustment. With respect to the large model solution space and complex constraints, a better solution algorithm is proposed based on ant colony algorithm for optimal quick solution. The simulation results show that the algorithm is feasible and the approximate optimal solution can be quickly obtained.     

Impact of Online Community Structure on Information Propagation: Empirical Analysis and Modeling

Online social networking sites (OSNS), as a popular social media platform, have been developed massively for business and research purposes. In this paper, it investigated the impact of community structure in online social network on information propagation. A SI (Susceptible-Infected) model based on community structure was proposed. In the SI model, the heterogeneity of user’s active time was taken into account. From the results, it was found that the number of links among communities determines the fraction of infected nodes. With the increase of the number of groups G, however, the fraction of infected nodes remains approximately constant. The simulation results will be of great significance: the information will last relatively short for group networks which have either a small or a large number of groups. The results can be useful for optimizing or controlling information, such as propagating rumors in online social networks.     

Effects of Heat Treatment on Dimension Stability of Larch Pallet Decks

The useful life of wooden pallets is lower because of the defects in lumbers. The quality of lumber can be significantly enhanced by heat treatment. In this paper, the larch pallet decks samples were heat-treated under the conditions of different time and temperatures. The quantity of water uptake has reduced 16.8％ under the condition of 250 ℃ for 150 min. The resistance of water absorption efficiency increases 165.34％ under the condition of 175 ℃ for 90 min. The anti-shrink efficiency increases 72.08％ under the condition of 250 ℃ for 90min. The results showed that the dimension stability of larch panels can be improved by heat treatment. The condition of 250 ℃ for 180 min is the best heat treating condition to improve the dimension stability.     

钙基固硫剂对水煤浆性能影响的研究

脱硫型水煤浆是一种新型的清洁水煤浆,在燃烧和气化过程中具有固硫作用,但固硫剂对水煤浆性能有一定影响。文中针对新汶水煤浆,在添加不同钙基固硫剂、不同Ca/S比时对水煤浆的粘度、稳定性、流变性和硫析出特性等进行了研究,结果表明固硫剂不会对水煤浆流变性本质产生影响,水煤浆仍然呈现为假塑性流体,但其粘度会增加,稳定性有所下降。无机钙对水煤浆性能影响要小于有机钙,在Ca/S=2时,添加无机钙后水煤浆粘度为1000~1200mPa·s。添加CaCO3(Ca/S=2)的水煤浆在1000oC燃烧,硫的析出率由98%下降到52%。