Yongkang Xiao

An Improved Cloud Rendering Method

Clouds play an important role for creating realistic images of outdoor scenes. Many methods have been proposed for modeling and rendering clouds. Among these methods, Dobashi et al. proposed a simple but efficient cloud rendering algorithm based on splatting algorithm and take into account single scattering in couds. This algorithm has been used in many papers to generate realistic clouds images. However, in images generated by using Dobashi’s method, lattice like artifact can be easily perceived. This paper describes a method to improve the quality of cloud image generated by dobashi method. We perturb the positions of cloud particles and resample the density at perturbed position within neighboring meatballs to remove the regular pattern from regular space lattice structure and adding noise to texture of billboard used in the original method.

Detecting and extracting text in video via sparse representation based classification method

This paper describes a new approach to detect and extract the video text more precisely and efficiently. The proposed approach combines the frame difference and the sparse representation based classification (SRC) method. The experiments demonstrated that the proposed method is effective and efficient for the both scenes, i.e. detecting and extracting the captions in a video the character in a sign.

Research of Interaction between TCP and MAC Protocol in Multihop Ad Hoc Networks

The paper first shows that TCPs congestion control mechanism based on packet-loss does not adapt well in multihop ad hoc networks. Then by modeling the MAC protocol, the interaction between the MAC protocol and TCP is pointed: the function of the MAC layer is to try its best to look for a group mutually exclusive job scheduling for the loaded traffic, whereas the function of transport layer is to adjust its traffic to ensure the existence of a feasible scheduling so that the MAC layer can find. By constructing the optimal MAC protocol according to the contention graph, we gain the maximum transmission rate of TCP senders which can assure the TCP fairness.

Content-Based Efficient Messages Transmission in WSNs

The WSNs are mainly to monitor various types of sensing content. In the automated control system, administration centers (ACs) often send notifications to a set of nodes meeting given content ranges to implement specific actions. For instance, we notify the sensing devices with sensing temperatures greater than 35 to turn on the cooling system. At present, the transmission of notification messages is mostly based on node identification, which is isolated from sensing contents and unable to accurately locate nodes meeting the sensing content requirements. In this paper, we generalize two types of sensing contents: the continuous values and the discrete values, and a content-based efficient message transmission mechanism (CEMT) is proposed for the typical tree-like topologies in WSNs. Thus, a highly effective notifying method for content-based multicast and anycast messages is designed, which accurately sends notification messages to nodes whose sensing values belong to the given range. Sometimes, multiple sensing types of nodes are mixed together to construct a net topology, offering underlying transport services to each other. At this point, CEMT builds a specialized logical tree for the same type of nodes, and notification messages are transmitted along the logical tree. CEMT reduces the transmission time, bandwidth, and number of processing nodes when a content-based message is sent, and it takes less storage of content routing entries in nodes.

A Notification Transmission Mechanism for Sensor Nodes Based on Sensing Contents in IoTs

Abstract The IoTs deployment is mainly used to monitor a variety of sensing contents. Meanwhile, management centers (MCs) often send notifications to nodes satisfying given content ranges to implement specific actions. At present, the transmission of notification messages fulfills routing mostly based on node identification, which is isolated from sensing contents and has low efficiency. In this paper, we generalize two types of sensing contents: the continuous value and the discrete value, and a notification transmission mechanism based on sensing content (NSEC) is proposed for tree-like topologies in IoTs. Thus, the highly effective notifying method for content-based multicast and anycast messages is designed, which accurately sends messages to nodes meeting corresponding conditions. NSEC reduces transmission time, bandwidth and number of processing nodes when a content-based message is sent.

PFPG: A novel MTU model for IPv4/IPv6 transition.

Transition techniques play a vital role during the evolvement process of the Internet from IPv4 to IPv6. However, packet length change during the forwarding process may result in fragmentation and reassembly of a large number of packets, which greatly impacts the forwarding performance. In addition, different Maximum Transmission Unit (MTU) mechanisms of IPv4 and IPv6 have also brought lots of troubles to transition techniques. Existing researches only provided preliminary ideas instead of any specific implementation methods. To this aim, the Pre-Fragment Packet in Gateway (PFPG) model is presented, which can insure that reassembly does not occur during packet forwarding. As PFPG is only implemented at transition gateway and nothing is done in terminal systems and other routers, the model with less deployment points can be easily maintained. Experiments indicate that PFPG can achieve preferable forwarding performance.

A Simple Real-Time Method for Modeling and Rendering Clouds

This paper proposes a simple real-time method for modeling and rendering clouds. The density of cloud is formed by simulating projected motion of cloud particles into 2D plane. And then we render it by using an algorithm that approximates single forward scattering in real-time. This method does not require any preprocess to shade the cloud. By using this method one can create a cloud very quickly and control the cloud shape in an easy way.