A converging pattern represents the process in which a collection of moving objects gradually converges toward a target area from various directions and eventually forms a dense group. Unlike most existing group patterns, it indicates the early formation of group events, which has a significant application for predicting and detecting emergency events. Existing studies of the converging pattern merely discover patterns from historical trajectories in an offline manner. However, online mining over streaming trajectories has a more practical impact in some real-world scenarios like real-time traffic monitoring . In this paper, we investigate online algorithms that enable converging pattern mining over network-constrained streaming trajectories of moving objects. To achieve synchronization with the speed of trajectory updates, we propose an incremental density-based clustering algorithm in the road network called I D C R N and a converging monitoring method to detect converging patterns in real-time. To efficiently retrieve the constantly evolving spatial relationship among objects in road networks with a large search space and an intractable computation complexity for network distance, we propose a dual index called M O R N to support continuous neighborhood query and cluster pruning in the road network . Extensive experiments with real and synthetic datasets validate the efficiency of our proposed index and methods.

MOTIVATION: Narrative visualization for scientific data explorations can help users better understand the domain knowledge, because narrative visualizations often present a sequence of facts and observations linked together by a unifying theme or argument. Narrative visualization in immersive environments can provide users with an intuitive experience to interactively explore the scientific data, because immersive environments provide a brand new strategy for interactive scientific data visualization and exploration. However, it is challenging to develop narrative scientific visualization in immersive environments. In this paper, we propose an immersive narrative visualization tool to create and customize scientific data explorations for ordinary users with little knowledge about programming on scientific visualization, They are allowed to define POIs (point of interests) conveniently by the handler of an immersive device. RESULTS: Automatic exploration animations with narrative annotations can be generated by the gradual transitions between consecutive POI pairs. Besides, interactive slicing can be also controlled by device handler. Evaluations including user study and case study are designed and conducted to show the usability and effectiveness of the proposed tool. AVAILABILITY: Related information can be accessed at: https://dabigtou.github.io/richenliu/.

Group pattern mining from spatio-temporal trajectories of moving objects have gained significant attentions due to the prevalence of location-acquisition devices and tracking technologies. In this work, we propose a new group pattern, named converging, which is a group of moving objects that converge from different directions for a certain time period. Examples of convergings may include traffic jams, troop assembly, serious stampedes, and other public congregations. As a proof-of-concept, we implemented a visual analytic system CPM based on road-network constrained trajectories to detect converging events in road networks. A user-friendly interface is designed to help users gain insights into converging events from spatial and temporal aspects. Finally, we demonstrate the effectiveness and efficiency of our system by using a real dataset.

A low-power full 3.1-10.6 GHz UWB transmitter using very simple 4-delay-cell 5th-derivative Gaussian pulse generation for carrier-free IR-UWB system is designed and fabricated in 0.13 mum CMOS. The fully integrated IR-UWB transmitter features on-chip compensated active balun and simple BPSK modulation. Measurement shows the lowest reported power of 33 pJ/pulse at 100 MHz PRF, short 5th-derivative Gaussian pulse width of 750 ps and Vppof 84 mV. This FCC-compliant IR-UWB transmitter allows up to 1.3 Gbps throughput for low-cost low-power hi-QoS wireless multimedia and video streaming.

A fully integrated, ultra low-power, varying pulse width second-order derivative Gaussian pulse generator designed and fabricated in a commercial 0.18μm CMOS technology is reported for 3-10GHz ultra wideband (UWB) transceivers. The second-order derivative Gaussian pulse generator circuit consists of three cascaded stages for generating square wave, Gaussian impulse, and second-order derivation sequentially. This CMOS second-order derivative Gaussian pulse generator can generate UWB pulses with adjustable pulse width ranging from 220 picoseconds to a few nanoseconds. Measured circuit performance achieves a very short pulse width of <1ns, an amplitude of 70mV and an ultra low power consumption of 2mW at 100MHz pulse repeating frequency. The pulse generator fully complies with FCC power mask.