A segmentation-based fine-grained peer sharing technique for delivering large media files in content distribution networks

Delivering large media files over the Internet is a challenging task because it has some unique features that are different from delivering conventional Web documents. In this paper, we propose a fine-grained peer sharing technique for dealing with the problem in the context of content distribution networks. The key difference of the technique from conventional peer-to-peer systems is that the unit of peer sharing is not a complete media file, but at a finer granularity. By doing so, we improve the flexibility of replica servers for handling client requests. We analyze the storage requirement at replica servers and design a scheduling algorithm to coordinate the delivery process from multiple replica servers to a client. Our simulations show that the fine-grained peer sharing approach can reduce the initial latency of clients and the rejection rate of the system significantly over a simple peer sharing method.     

大型对开组合齿圈工艺设计分析及其最优化

本文论述了大型齿圈的结构特征及其现行工艺的合理性；在建立工艺关键环节概念的基础上提出工艺优化方案。并从理论上论证了实现最优化的充分可能性。     

Multirobot-Based Nanoassembly Planning with Automated Path Generation

In this paper, a novel approach of automated multirobot nanoassembly planning is presented. This approach uses an improved self-organizing map to coordinate assembly tasks of nanorobots while generating optimized motion paths at run time with a modified shunting neural network. It is capable of synchronizing multiple nanorobots working simultaneously and efficiently on the assembly of swarms of objects in the presence of obstacles and environmental uncertainty. Operation of the presented approach is demonstrated with experiments at the end of the paper.     

Detection of failure sites by focused ion beam and nano-probing in the interconnect of three-dimensional stacked circuit structures

Focused ion beam (FIB) and nano-probing were applied for failure analysis of three-dimensional stacked circuits with copper through-silicon-vias between the stacked chips. The failure analysis was done after high temperature storage and thermal cycling tests. Passive voltage contrast in FIB allowed to pinpoint the open sites. FIB cross-sections showed the presence of opens at the bottom of the copper vias. The failure cause was suspected to be an interlayer particle, which was confirmed by optical profilometry. Nano-probing was used on another sample to pinpoint the failure location through the measurement of the local resistance within the daisy chains. The failure was traced out to be related with surface contamination.     

La doping effects on intergrowth Bi2WO6–Bi3TiNbO9 ferroelectrics

La doping effects on intergrowth Bi₂WO₆–Bi₃TiNbO₉ ferroelectric ceramics were studied by X-ray diffraction, electron probe microanalysis and dielectric spectroscopy. It was found that the La³⁺ distribution, ferroelectric phase transition and dielectric relaxation behavior are apparently affected by La doping. With increasing La³⁺ content, the site of dopant ion varies, the grain growth of Bi₅TiNbWO₁₅ is restrained, the Curie temperature is reduced and broadened. Furthermore, two dielectric relaxation loss peaks were observed both in temperature and frequency spectra. The calculated relaxation parameters revealed the oxygen vacancy related to the relaxation process.     

Polyol-mediated synthesis of water-soluble LaF3:Yb,Er upconversion fluorescent nanocrystals

Well-crystallized LaF₃:Yb,Er nanoparticles were prepared by the polyol method and three kinds of polyols (glycol, diethylene glycol and glycerol) were chosen as the reaction medium respectively. All of the obtained LaF₃:Yb,Er nanoparticles have roughly spherical shapes, and the average sizes of these nanoparticles ranged from 5 to 7 nm. These nanoparticles could be well dispersed in water or ethanol to form colloidal solutions. When these nanoparticles were excited by the 980 nm laser, several upconversion emissions were observed.     

三相异步电动机运行指标的分析

利用电机学理论分析了影响电机起动转矩、起动电流、最大转矩和最小转矩的因素。     

Extensions of LDA by PCA mixture model and class-wise features

Linear discriminant analysis (LDA) is a data discrimination technique that seeks transformation to maximize the ratio of the between-class scatter and the within-class scatter. While it has been successfully applied to several applications, it has two limitations, both concerning the underfitting problem. First, it fails to discriminate data with complex distributions since all data in each class are assumed to be distributed in the Gaussian manner. Second, it can lose class-wise information, since it produces only one transformation over the entire range of classes. We propose three extensions of LDA to overcome the above problems. The first extension overcomes the first problem by modelling the within-class scatter using a PCA mixture model that can represent more complex distribution. The second extension overcomes the second problem by taking different transformation for each class in order to provide class-wise features. The third extension combines these two modifications by representing each class in terms of the PCA mixture model and taking different transformation for each mixture component. It is shown that all our proposed extensions of LDA outperform LDA concerning classification errors for synthetic data classification, hand-written digit recognition, and alphabet recognition.     

Formation of mushroom-like ZnO microcrystals through a solution calcination process

Mushroom-like ZnO microcrystals have been prepared via a solution calcination route, using Zn(NO₃)₂ as Zn source in the absence of any surfactants, templates or catalysts. This is the first example to prepare mushroom-like crystals as semiconductors, which are expected to show particular physical properties. The ZnO products were investigated by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy and photoluminescence (PL) spectrum measurements. A suitable concentration of Zn(NO₃)₂ solution was important for the growth of the mushroom-like products. The reported synthetic procedure is straightforward and inexpensive, and thus can be readily adopted to produce large quantities of mushroom-like ZnO microcrystals.     

含钡合金的生产及其对钢液脱氧行为的研究

介绍了含钡合金的生产状况。在MoSi2炉上对钢管钢进行了含钡合金脱氧行为的研究，然后在150tLF／VD精炼设备上进行了使用含钡合金的工业试验。研究中主要选取SiAlBa、SiCaBa、SiAlBaCa、SiAlBaCaSr及用于钙处理的SiCa包芯线，并选用Al和FeSiAl作为对比脱氧剂，分别考察了实验室条件下和实际生产过程中，采用钡系合金对钢液脱氧的全氧含量，脱氧产物的分布、尺寸和形貌，探讨了钡系合金脱氧和对夹杂物的变质作用的机理。