A comparative study between PVO-based framework and multi-predictor mechanism in reversible data hiding

Sorting-based reversible data hiding (RDH) methods like pixel-value-ordering (PVO) can predict pixel values accurately and achieve an extremely low distortion on the embedded image. However, the excellent performance of these methods was not well explained in previous works, and there are unexploited common points among them. In this paper, we propose a general multi-predictor (GMP) framework to summarize PVO-based RDH methods and explain their high prediction accuracy. Moreover, by utilizing the proposed GMP framework, a more efficient sorting-based RDH method is given as an example to show the generality and applicability of our framework. Comparing with other PVO-based methods, the proposed example method can achieve significant improvement in embedding performance. It is hopeful that more efficient sorting-based RDH algorithms can be designed according to our proposed framework by designing better predictors and their combination methods.     

Experimental investigation on gasification characteristics of polycarbonate (PC) microplastics in supercritical water

In order to solve the problem of marine microplastics and realize the harmless resource utilization of plastics, the gasification experiments of polycarbonate (PC) microplastics were carried out in supercritical water and a novel seawater gasification of microplastic experiment was investigated. In this paper, the effects of different operating conditions (temperature, time, feedstock concentration, pressure) on gasification performance were discussed. The gasification kinetic of microplastics in supercritical water was calculated. The experimental results showed that the increase in gasification temperature and time enhanced the cracking reaction and free radical reaction of the microplastics to increase the gasification efficiency, while the reduction in feedstock concentration improved the gasification efficiency by increasing the gasification level of unit feedstock. The change in pressure had no significant effect on gasification due to the fact that the properties of the supercritical water were not significantly changed. It was found that the valuable results that all alkali metal salts in seawater promote hydrogen conversion, while in terms of carbon conversion, only KCl, CaCl₂, NaHCO₃ and seawater had a significant catalytic effect on the gasification. Seawater gasification of microplastics was a potential resource utilization method. Finally, it was considered that the PC plastic gasification conformed to the random nucleation and subsequent growth model (n = 3), and the reaction activation energy was 230.45 kJ/mol, which was smaller than that of traditional pyrolysis.     

Influence of thermodynamic activities of different masteralloys in pack powder mixtures to produce low activity aluminide coatings on TiAl alloys

Titanium aluminides are interesting high temperature materials, but show insufficient oxidation resistance as well as embrittlement at higher temperatures (>750 °C). Al-enriched coatings can be manufactured by pack cementation on many high temperature alloys to promote the formation of a protective alumina layer at high temperatures, which not only protects the alloy from oxidation but is also expected to impede embrittlement of TiAl at high temperatures. One drawback of such coatings is that Al-rich phases are very brittle. Therefore the major intermetallic aluminide phase in the coating plays a critical role for the protection behavior. Based on thermodynamic calculations different masteralloys were chosen to control the pack cementation process. Particular attention is given to the gradient between the aluminum activity of the different masteralloy powders and the aluminum activity of the substrate surface (alloy TNM^®-B1) in order to control the deposited phase at the surface. It is revealed that powder pack with Al as masteralloy provides a high Al activity and produces thick multi-layered coatings consisting of brittle TiAl₃ and TiAl₂ phase and aluminum-rich TiAl. By using different chromium aluminides as masteralloys, thinner, low-activity coatings could be produced, consisting of a bi-layer of brittle TiAl₂ phase and aluminum-rich TiAl or just the targeted pure aluminum-rich TiAl, which is known to have much better mechanical properties.     

Multi-path connected network for medical image segmentation

In recent years, deep learning has been successfully applied to medical image segmentation. However, as the network extends deeper, the consecutive downsampling operations will lead to more loss of spatial information. In addition, the limited data and diverse targets increase the difficulty for medical image segmentation. To address these issues, we propose a multi-path connected network (MCNet) for medical segmentation problems. It integrates multiple paths generated by pyramid pooling into the encoding phase to preserve semantic information and spatial details. We utilize multi-scale feature extractor block (MFE block) in the encoder to obtain large and multi-scale receptive fields. We evaluated MCNet on three medical datasets with different image modalities. The experimental results show that our method achieves better performance than the state-of-the-art approaches. Our model has strong feature learning ability and is robust to capture different scale targets. It can achieve satisfactory results while using only 0.98 million (M) parameters.     

Guided filter-driven kernel fuzzy clustering with local information for noise image segmentation

Multimedia Tools and Applications - Fuzzy local information clustering is the most widely robust segmentation methods, but it is only suitable for image corrupted by certain intensity noise. Later,...     

Shape transformer nets: Generating viewpoint-invariant 3D shapes from a single image

Single-view 3D shapes generation has achieved great success in recent years. However, current methods always blind the learning of shapes and viewpoints. The generated shape only fit the observed viewpoints and would not be optimal from unknown viewpoints. In this paper, we propose a novel encoder–decoder based network which contains a disentangled transformer to generate the viewpoint-invariant 3D shapes. The differentiable and parametric Non-uniform B-spline (NURBS) surface generation and 3D-to-3D viewpoint transformation are incorporated to learn the viewpoint-invariant shape and the camera viewpoint, respectively. Our new framework allows us to learn the latent geometric parameters of shapes and viewpoints without knowing the ground truth viewpoint. That can simultaneously generate camera-viewpoint and viewpoint-invariant 3D shapes of the object. We analyze the effects of disentanglement and show both quantitative and qualitative results of shapes generated at various unknown viewpoints.     

基于SQL Server2005库存管理系统的设计与实现

为全面管理仓库中储存的商品和货物,缩短库存信息流转时间,使企业的物料管理层次分明、井然有序,并为采购、销售和生产提供依据,提高企业的经营效率。设计并实现了基于SQL Server2005的库存管理系统。应用结果表明该系统节约了成本,提高了企业的经营效率,并具有较强的实用性和可移植性。     

液体火箭发动机涡轮泵转子的新型动平衡方法研究

针对液体火箭发动机涡轮泵的运行特点,提出了利用起动过程的不平衡响应信息进行涡轮泵转子模态平衡的两种新方法。方法1将转子的前两阶模态不平衡分别等效为模态不平衡方位角和模态不平衡大小,在前两阶临界区内,通过转子的升速不平衡响应信息识别出对应阶模态不平衡方位角,然后利用各阶模态间的正交关系,添加合理的平衡试重组,通过两次升速起动过程完成转子前两阶模态的平衡;方法2引入了测点模态比的概念,在3圆平衡法的基础上,通过4次升速起动过程,完成了转子前两阶模态的平衡。最后通过模型实验对所提出的两种新型平衡方法进行了验证