Multiple clusterings of heterogeneous information networks

Machine Learning - Traditional clustering algorithms focus on a single clustering result; as such, they cannot explore potential diverse patterns of complex real world data. To deal with this...     

仿人足球机器人射门过程中路径规划算法研究

为了解决仿人足球机器人射门最优路径规划问题,本文提出一种基于模糊算法的移动机器人路径规划策略,使机器人能够高效率踢球射门.利用机器人摄像头感知周围的环境信息,再利用超声波传感器得到与目标物相关的距离信息,运用模糊推理将目标位置信息模糊化,建立模糊规则并求解,最终使机器人可以确定射门的路径,进而采用正向射门或侧向射门动作.     

Maximum error-bounded Piecewise Linear Representation for online stream approximation

Given a time series data stream, the generation of error-bounded Piecewise Linear Representation (error-bounded PLR) is to construct a number of consecutive line segments to approximate the stream, such that the approximation error does not exceed a prescribed error bound. In this work, we consider the error bound in \(L_\infty \) norm as approximation criterion, which constrains the approximation error on each corresponding data point, and aim on designing algorithms to generate the minimal number of segments. In the literature, the optimal approximation algorithms are effectively designed based on transformed space other than time-value space, while desirable optimal solutions based on original time domain (i.e., time-value space) are still lacked. In this article, we proposed two linear-time algorithms to construct error-bounded PLR for data stream based on time domain, which are named OptimalPLR and GreedyPLR, respectively. The OptimalPLR is an optimal algorithm that generates minimal number of line segments for the stream approximation, and the GreedyPLR is an alternative solution for the requirements of high efficiency and resource-constrained environment. In order to evaluate the superiority of OptimalPLR, we theoretically analyzed and compared OptimalPLR with the state-of-art optimal solution in transformed space, which also achieves linear complexity. We successfully proved the theoretical equivalence between time-value space and such transformed space, and also discovered the superiority of OptimalPLR on processing efficiency in practice. The extensive results of empirical evaluation support and demonstrate the effectiveness and efficiency of our proposed algorithms.     

Fast intrusion detection based on a non-negative matrix factorization model

In this paper, we present an efficient fast anomaly intrusion detection model incorporating a large amount of data from various data sources. A novel method based on non-negative matrix factorization (NMF) is presented to profile program and user behaviors of a computer system. A large amount of high-dimensional data is collected in our experiments and divided into smaller data blocks by a specific scheme. The system call data is divided into blocks by processes, while command data is divided into consecutive blocks with a fixed length. The frequencies of individual elements in each block of data are computed and placed column by column as data vectors to construct a matrix representation. NMF is employed to reduce the high-dimensional data vectors and anomaly detection can be realized as a very simple classifier in low dimensions. Experimental results show that the model presented in this paper is promising in terms of detection accuracy, computation efficiency and implementation for fast intrusion detection.     

一种高性能二阶荷控忆阻器电路设计与验证

当前忆阻器等效电路中的传统运算放大器存在功耗高、噪声大等问题。针对这些问题,基于简化差分对设计了两种极简化的运算放大器。通过电路仿真对两种简化运算放大器与传统运算放大器进行功耗与噪声仿真分析。结果表明,与三种传统运算放大器相比,该简化运算放大器的功耗最低,抗噪声性能最优。运算放大器的总功耗为15 mW,等效输出噪声电压为11.55 nV·Hz-1/2,噪声系数为35.873 dB。基于两种简化运算放大器,设计了一种二阶荷控忆阻器等效电路。通过理论分析、电路仿真和硬件电路板基实验,对该等效电路的忆阻特性进行了分析与验证。     

An effective suggestion method for keyword search of databases

This paper solves the problem of providing high-quality suggestions for user keyword queries over databases. With the assumption that the returned suggestions are independent, existing query suggestion methods over databases score candidate suggestions individually and return the top-k best of them. However, the top-k suggestions have high redundancy with respect to the topics. To provide informative suggestions, the returned k suggestions are expected to be diverse, i.e., maximizing the relevance to the user query and the diversity with respect to topics that the user might be interested in simultaneously. In this paper, an objective function considering both factors is defined for evaluating a suggestion set. We show that maximizing the objective function is a submodular function maximization problem subject to n matroid constraints, which is an NP-hard problem. An greedy approximate algorithm with an approximation ratio O(\(\frac {1}{1+n}\)) is also proposed. Experimental results show that our suggestion outperforms other methods on providing relevant and diverse suggestions.     

一种实现时序快速有效收敛的时钟树综合方案

针对低频下数字集成电路实现时序收敛需要插入大量缓冲器而导致芯片布线困难、运行时间较长等问题,提出了一种降低时钟树级数与增加保持时间余量相结合的时钟树综合方案。基于CSMC 0.35 μm CMOS工艺,采用提出的方案,使用IC Compiler和Prime Time工具,分别完成了应用于高精度隔离型Σ-Δ ADC芯片的低速数字滤波器的物理设计以及静态时序分析。结果表明,与传统方案相比,保持时间负松弛总值降低了95.62%,时序收敛所需缓冲器个数减少了约98.13%,运行时间缩短了97.25%,有效地降低了布线拥塞程度,快速有效地实现了时序收敛。     

pH‐ and NIR Light‐Responsive Micelles with Hyperthermia‐Triggered Tumor Penetration and Cytoplasm Drug Release to Reverse Doxorubicin Resistance in Breast Cancer

The acquisition of multidrug resistance (MDR) is a major hurdle for the successful chemotherapy of tumors. Herein, a novel hybrid micelle with pH and near‐infrared (NIR) light dual‐responsive property is reported for reversing doxorubicin (DOX) resistance in breast cancer. The hybrid micelles are designed to integrate the pH‐ and NIR light‐responsive property of an amphiphilic diblock polymer and the high DOX loading capacity of a polymeric prodrug into one single nanocomposite. At physiological condition (i.e., pH 7.4), the micelles form compact nanostructure with particle size around 30 nm to facilitate blood circulation and passive tumor targeting. Meanwhile, the micelles are quickly dissociated in weakly acidic environment (i.e., pH ≤ 6.2) to release DOX prodrug. When exposed to NIR laser irradiation, the hybrid micelles can trigger notable tumor penetration and cytosol release of DOX payload by inducing tunable hyperthermia effect. In combination with localized NIR laser irradiation, the hybrid micelles significantly inhibit the growth of DOX‐resistant MCF‐7/ADR breast cancer in an orthotopic tumor bearing mouse model. Taken together, this pH and NIR light‐responsive micelles with hyperthermia‐triggered tumor penetration and cytoplasm drug release can be an effective nanoplatform to combat cancer MDR.     

窄问隙埋弧焊工艺在H型钢梁生产中的应用

以板厚为20mm的Q345-B钢材为对象,采用埋弧自动焊工艺,通过4组试件研究构件组装间隙和构件施焊时摆放倾角对T型接头熔深的影响。通过接头宏观金相观察和力学性能试验,得出结论：构件组装时预留合适的间隙,施焊时摆放较大的倾角均有利于增加接头的熔深值,且质量也可得到保障。     

In-situ observation of grain refinement in the simulated heat-affected zone of high-strength low-alloy steel by Zr-Ti combined deoxidation

The effect of Zr-Ti combined deoxidation on the grain refinement in the simulated coarse-grained heat-affected zone of a high-strength low-alloy steel was investigated by means of analytical characterization techniques such as in-situ microscopy, transmission electron microscopy, and electron backscattered diffraction analysis. Owing to the Zr-Ti combined deoxidation, a large amount of fine Zr-Ti oxide particles were formed in the steel and retarded the austenite grain growth during simulated welding thermal cycle. The austenite grains were small and uniform. The Mn can diffuse spontaneously from austenite to Zr-Ti oxide inclusion and MnS precipitated on ZrO₂, which can form Mn depleted zone in the vicinity of inclusion. The acicular ferrite grains nucleated on intragranular Zr-Ti oxide inclusions in austenite grains grew in different directions and effectively divided the austenite grain into several finer and separate regions at intermediate temperature. The crystallographic grain size became small in the simulated coarse-grained heat-affected zone of Zr-Ti-killed steel due to the effective pinning effect by Zr-Ti oxide particles and acicular ferrite formation.