Optimisation of specimen temperature and pulse fraction in atom probe microscopy experiments on a microalloyed steel

This paper details the effects of systematic changes to the experimental parameters for atom probe microscopy of microalloyed steels. We have used assessments of the signal-to-noise ratio (SNR), compositional measurements and field desorption images to establish the optimal instrumental parameters. These corresponded to probing at the lowest possible temperature (down to 20 K) with the highest possible pulse fraction (up to 30%). A steel containing a fine dispersion of solute atom clusters was used as an archetype to demonstrate the importance of running the atom probe at optimum conditions.     

SuperVlan技术的网络组网方法

本文提出一种利用超级虚拟局域网(SuperVlan)技术的组网方法,在接入交换机上的每个端口分配一个VLAN(即每个用户分配一个VLAN),使得入网用户之间二层通讯相互隔离,达到有效的解决网络环路、ARP攻击、DHCP欺骗等问题造成的网络故障。     

A Comparative Study of Two Wayfinding Aids With Simulated Driving Tasks—GPS and a Dual-Scale Exploration Aid

Global Positioning System (GPS) is currently the most often used wayfinding aid for driving. Yet GPS is originally designed to provide a driving guide rather than to help users gain spatial knowledge. Accordingly, GPS might be less usable in situations where spatial knowledge is required. This study experimentally compared two wayfinding aids using simulated driving tasks in a virtual environment: a simulated GPS and a dual-scale exploration aid (DSEA). The DSEA, which provides two levels of details—both detailed and contextual information—was proposed to support participants in finding and selecting routes by themselves. The results show that although DSEA was less helpful in leading participants to their destination and corresponded to more turning errors in simulated driving, it was more useful for the corresponding participants to establish spatial awareness and a cognitive map. The influence of participants' spatial ability test score on wayfinding performance was measured and discussed. The proposed DSEA design and experimental results show some indications for designing new wayfinding aids aimed at reducing wayfinding errors and constructing cognitive maps while still providing easy navigation.     

On the Accuracy of Packet Delay Estimation in Distributed Service Networks

Packet delay (either one-way time or round-trip time) is a very important metric for measuring the performance of networks in a highly dynamic environment such as the Internet. Many network applications are also sensitive to packet delay or delay variation for ensuring an acceptable level of quality in providing network-based services such as VoIP, multimedia streaming, etc. A very important property of packet delay is that it is very dynamic and therefore should be measured frequently with measurement results being updated on a timely basis. Measurement of packet delay has thus generated a great deal of interest in the past years and a lot of research has been performed in the development of measurement architecture as well as specific measurement techniques. However, how to reduce network overhead resulting from measurement while achieving a reasonable level of accuracy still remains a challenge. In this paper, we propose to use delay estimation as an alternative to delay measurement for reducing measurement overhead and, in particular, examine the level of accuracy that delay estimation can achieve. With delay estimation, measurement nodes can be dynamically selected and activated and other nodes can share measurement results by performing delay estimation, thus reducing measurement overhead while supporting the dynamic requirement for delay measurement. Consequently, while measurement overhead can be reduced by activating only a subset of network nodes to perform actual measurement, desired accuracy can be achieved by exploring the correlation between delays as well as by sharing measurement results to do delay estimation based on such a correlation. We illustrate how packet delays of network nodes can correlate to each other based on topological properties and show how delays can be estimated based on such a correlation to meet accuracy requirements, which would make delay measurement in the Internet highly dynamic and adaptable to the accuracy requirements and measurement results highly reliable. We also show how delay estimation can be applied by presenting three application scenarios as well as an example to demonstrate the usefulness and effectiveness of delay estimation in the measurement of packet delays.     

Wii remote–based low-cost motion capture for automated assembly simulation

This paper describes the development of a Wii remote (Wiimote)–based low-cost motion capture system and demonstrates its application for automated assembly simulation. Multiple Wiimotes are used to form a vision system to perform motion capture in 3D space. A hybrid algorithm for calibrating a multi-camera stereo vision system has been developed based on Zhang’s and Svoboda’s calibration algorithms. This hybrid algorithm has been evaluated and shown accuracy improvement over Svoboda’s algorithm for motion capture with multiple cameras. The captured motion data are used to automatically generate an assembly simulation of objects represented by CAD models in real time. The Wiimote-based motion capture system is practically attractive because it is inexpensive, wireless, and easily portable. Application examples have been developed for a single vision system with two Wiimotes to track the assembly of a microsatellite prototype frame and for an integrated vision system with four Wiimotes to track the assembly of a bookshelf.     

Solving non-negative matrix factorization by alternating least squares with a modified strategy

Non-negative matrix factorization (NMF) is a method to obtain a representation of data using non-negativity constraints. A popular approach is alternating non-negative least squares (ANLS). As is well known, if the sequence generated by ANLS has at least one limit point, then the limit point is a stationary point of NMF. However, no evdience has shown that the sequence generated by ANLS has at least one limit point. In order to overcome this shortcoming, we propose a modified strategy for ANLS in this paper. The modified strategy can ensure the sequence generated by ANLS has at least one limit point, and this limit point is a stationary point of NMF. The results of numerical experiments are reported to show the effectiveness of the proposed algorithm.     

Transductive multi-distance learning for video search

Graph-based semi-supervised learning approaches have been proven effective and efficient in solving the problem of the inefficiency of labeled training data in many real-world application areas, such as video annotation. As a significant factor of these algorithms, however, pair-wise similarity metric of samples has not been fully investigated. Specifically, for existing approaches, the estimation of pair-wise similarity between two samples relies on the spatial property of video data. On the other hand, temporal property, an essential characteristic of video data, is not embedded into the pair-wise similarity measure. Accordingly, in this paper, a novel framework for video annotation, called Joint Spatio-Temporal Correlation Learning (JSTCL) is proposed. This framework is characterized by simultaneously taking into account both the spatial and temporal property of video data to improve the estimation of pair-wise similarity. We apply the proposed framework to video annotation and report superior performance compared to key existing approaches over the benchmark TRECVID data set.     

盐城市实行最严格水资源管理制度的实践与思考

江苏省盐城市在实行最严格水资源管理制度的初步实践中,深入思考了制定最严格的地下水管理政策、试点差别水资源费与差别水价制度、实施区域水质交接与生态补偿制度、提升水资源管理和节水科研水平、严格水资源管理问责与考评制度等实行最严格水资源管理制度的对策措施,为沿海地区加快实施最严格水资源管理制度提供借鉴。     

一种地震属性图像配色阈值选取算法

针对传统的地震属性图像可视化过程中存在的缺点,论文提出一种基于直方图技术的地震属性图像配色阈值选取算法,该算法利用直方图统计的结果,首先进行阈值预选,然后在区间内进行阈值调整,最后根据所确定的阈值对地震属性图像进行重新配色,很好地解决了传统地震属性图像视觉上的杂乱以及区域性差的缺点。经过对大庆油田多个区块地震属性图像的分析,该算法可有效解决地震图像可视化中的不足,提高了地震解释工作的效率。     

Joint video adaptation and erasure code for video broadcast in wireless networks

Advances in wireless access technologies such as WiMax and LTE have accelerated the development of wireless video applications.Though existing erasure codes are designed for wireless data broadcasting,their potential can only be realized for wireless video broadcasting if the distortions associated with video packets and their complex decoding dependency are taken into consideration.In this paper,we propose the greedy video erasure code(GVEC)to minimize average video distortion by accounting for the temporal scalable decoding dependency among video frames e.g.I,P and B frames in MPEG.GVEC is a greedy algorithm and sufers from high computational complexity.For practical implementation,we have designed the joint video adaptation and erasure code(JVEC)with lower complexity,which can generate erasure codes on the fly to guarantee the decoding of important video frames.Simulation results show that the performance of JVEC is very close to that of GVEC,and is superior to that of existing erasure codes.Our results also show the existence of a performance tradeof between video distortion and video packet throughput.