Effects of Cu on Microstructures,Mechanical, and Magnetic Properties of Fe–Ni–P Alloys Fabricated by Liquid Phase Sintering

The Fe–Ni–P–Cu alloys with different copper content (0, 0.5, 1, and 2 wt%) are fabricated by liquid phase sintering (LPS) at 950 °C. The nano‐Cu powder is mechanically mixed for 90 min with Fe–Ni–P composite powder using the ethanol as the medium. The microstructure, microhardness and compressive properties of Fe–Ni–P–Cu alloys are investigated. The results indicate that the copper is beneficial to improve the mechanical properties of sintered specimens. The sample contains a small amount of γ‐(Fe, Ni) phase when the copper content is 1 wt%, which results in its the highest compressive yield strength (948.1 MPa). The highest microhardness of 371 HV is accessible in Fe–Ni–P–Cu alloy with 2 wt% Cu. The fracture surface analysis indicates that sintered specimens with Cu addition exhibit a typical intergranular mode.     

多元随机回归系数和参数的线性估计可容许的几个结果

在两种矩阵损失函数下讨论随机效应多元线性模型中回归系数和参数的线性估计的可容许性,并且在齐次和非齐次线性估计类中分别得到了可容许估计的充要条件。     

陶瓷刀具模糊可靠性及其与刀具材料力学性能的关系

基于模糊数学和可靠性数学的基本理论 ,阐述了刀具模糊可靠性的基本概念和评价方法 ,并进一步应用于陶瓷刀具研究领域 ,建立了陶瓷刀具模糊可靠性与刀具材料力学性能的关系 ,从而使得不做或少做切削实验就能评价陶瓷刀具可靠性的设想成为可能     

砂轮平衡精度的最小二乘测试计算法

提出一种测算砂轮不平衡精度的最小二乘新方法 ,给出基本原理和具体算法 .该方法能有效抑制测量误差的影响 ,大大提高测试精度 ;并能同时测出残余不平衡量的大小和相位 .可用于各类平衡器的精度测定     

A content and user-oblivious video-recommendation algorithm

Videos have become popular on Internet, and corresponding video-recommendation algorithms have become an important factor for maintaining user’s satisfactory level and the profits of video-service providers. Existing recommendation algorithms are often highly dependent on the precious information of contents and users. However in many scenarios those information is not available for privacy reasons. This paper provides a watching sequence-based video-recommendation algorithm that can work well without the video contents and users information. The algorithm consists of three models: the exactly prefix matching tree, partial prefix matching tree, and the postfix matching tree. The final recommendation results are composed from the three models. The corresponding search tree, the matching search tree, and weight calculating algorithm are developed for each model. The algorithm is evaluated based on the half-year log files of a practical video website. The experimental results show that our algorithm performs better on execution time, accuracy, diversity of recommendation results, and non-hot coverage than the traditional recommendation algorithms.     

PK301故障原因分析及改进措施

聚丙烯装置的关键设备PK301频繁故障停车,通过分析各类故障发生原因,着重解决气相带粉问题和分液罐除沫器结构,通过运行考核,机组实现了长周期运转实现长周期运行14个月不大修.     

Automatic text summarization based on latent semantic indexing

Automatic summarization is a topic of common concern in computational linguistics and information science, since a computer system of text summarization is considered to be an effective means of processing information resources. A method of text summarization based on latent semantic indexing (LSI), which uses semantic indexing to calculate the sentence similarity, is proposed in this article. It improves the accuracy of sentence similarity calculations and subject delineation, and helps the abstracts generated to cover the documents comprehensively as well as reducing redundancies. The effectiveness of the method is proved by the experimental results. Compared with the traditional keyword-based vector space model method of automatic text summarization, the quality of the abstracts generated was significantly improved.     

Scaling the formation of slug bubbles in microfluidic flow-focusing devices

The present study aims at scaling the formation of slug bubbles in flow-focusing microfluidic devices using a high-speed digital camera and a micro particle image velocimetry (μ-PIV) system. Experiments were conducted in two different polymethyl methacrylate square microchannels of respectively 600 × 600 and 400 × 400 μm. N₂ bubbles were generated in glycerol–water mixtures with several concentrations of surfactant sodium dodecyl sulfate. The influence of gas and liquid flow rates, the viscosity of the liquid phase and the width of the microchannel on the bubble size were explored. The bubble size was correlated as a function of the width of the microchannel W _c, the ratio of the gas/liquid flow rates Q _g/Q _l and the liquid Reynolds number. During the pinch-off stage, the variation of the minimum width of the gaseous thread W _m with the remaining time could be scaled as _boxclose_boxclose ()^ - 0.15 (T - t)^1/3 . W_{\text{m}} \propto ({\frac{{Q_{\text{g}} }}{{Q_{\text{l}} }}})^{ - 0.15} (T - t)^{1/3} . The velocity fields in the liquid phase around the thread, determined by μ-PIV measurements, were obtained around a forming bubble to reveal the role of the liquid phase.     

MR编码在传真图像编码中的仿真应用

传真图像的信息量非常大,对其进行数据压缩,不仅可以节省存储空间,而且可以有效地降低传输时间。采用MR编码对传真图像进行数据压缩,设计了压缩和解压缩编码算法。仿真实验表明,该算法可以满足传真图像对压缩比和压缩速度的要求,且有效可行。     

多点测温与长线传输在分布式测温系统中的研究

针对分布式温度测量系统中多点温度测量问题,设计了长线传输电路.详细阐述了利用一个I/O端口连接多个传感器来编制公用程序的方法,以实现多个温度测量的方法,较好地解决了多个I/O口多点测温的设计问题;给出了单总线温度传感器多点测温硬件连接方法,解决了数字温度传感器在长线传输中温度的正确读取以及电路设计的关键问题.