This paper analyses the problem of time-synchronization of distributed sensor nodes. We present a Syncob, a method for synchronizing an arbitrary number of nodes in a distributed setting without the requirements of an...
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ISBN:
(纸本)9781424412310
This paper analyses the problem of time-synchronization of distributed sensor nodes. We present a Syncob, a method for synchronizing an arbitrary number of nodes in a distributed setting without the requirements of an infrastructure, master node or time and resource consuming protocol overhead. Syncob is therefore also very good suited for highly mobile settings with ad-hoc communication. Syncob is implemented as a physical layer protocol and provides a time synchronization deviation of max. 4 mu s between any participating node. Our implementation on low-cost pPart sensor nodes shows that Syncob requires very low overhead and very low complexity for hardware and software.
Unmanned Aerial Vehicles (UAVs) are increasingly being used to perform tasks either individually, or in groups. As more and more applications of UAV platoons are emerging, it is becoming apparent that coordination bas...
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ISBN:
(纸本)9798350371000;9798350370997
Unmanned Aerial Vehicles (UAVs) are increasingly being used to perform tasks either individually, or in groups. As more and more applications of UAV platoons are emerging, it is becoming apparent that coordination based on dynamically sensed information is critical for mission success. In this paper, we have addressed the concerns of fallible communication and an unreliable system on UAV platoon coordination. We have studied how robustness may be designed in a multi-agent scenario with arbitrary number of agents and developed an algorithm which guarantees distributed partial state synchronization with bounded variance in number of states despite facing message loss or system failure in agents. Our algorithm allows agents to autonomously take corrective actions in order to ensure the system remains stable. Results show that our algorithm is efficient, scalable and highly capable of achieving these goals.
AGATA is a 4-pi array of high purity Ge detectors for in-beam gamma-ray spectroscopy based on the novel concepts of pulse shape analysis (PSA) and gamma-ray tracking. Tracking and PSA require the concurrent digitizati...
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AGATA is a 4-pi array of high purity Ge detectors for in-beam gamma-ray spectroscopy based on the novel concepts of pulse shape analysis (PSA) and gamma-ray tracking. Tracking and PSA require the concurrent digitization-at a sampling rate of 100 Msamples/s-of preamplifier signals of the 36-fold segmented Ge crystals composing the array. Locally digitized data are optically transferred to remote pre-processing nodes for pulse energy computation. The design of the front-end readout and level-1 (M) trigger in AGATA follows a synchronous pipeline model: the detector data are stored in pipeline buffers at the global AGATA frequency, waiting the global L1 decision. A global timing system provides a reference clock and time tag to the digitizers;and the pre-processing units by means of a tree of optically connected timing units. Pre-processing nodes are integrated in AdvancedT CA-based carrier cards with full mesh connectivity in the backplane and read-out through pci-express based optical links. The front-end data readout and its integration in the global trigger and synchronization system will be described.
This study presents a distributed synchronous control in multiple electrohydraulic actuators (MEHAs), which ensures the motion consensus between the leader and the follower under a directed topology. Since the MEHAs s...
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This study presents a distributed synchronous control in multiple electrohydraulic actuators (MEHAs), which ensures the motion consensus between the leader and the follower under a directed topology. Since the MEHAs system has many unknown uncertainties and communication delays, a terminal sliding mode observer (TSMO) is used to address hydraulic parametric uncertainties and load disturbance. Furthermore, one synchronized controller is designed by Lyapunov-Krasovskii method with backstepping iteration to ensure the synchronized errors of the MEHAs system converging to a zero neighborhood. Since some follower EHAs cannot directly acquire the position signal from the leader node, a demand estimation law is used to degrade the negative effect of unknown communication delay existed in the network topology. Finally, the effectiveness of the proposed synchronized controller is verified by a MEHAs platform with finite hydraulic nodes under constant and random communication delays.
distributed shared memory (DSM) systems on top of network of workstations are especially vulnerable to the impact of false sharing because of their higher memory transaction overheads and thus higher false sharing pen...
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distributed shared memory (DSM) systems on top of network of workstations are especially vulnerable to the impact of false sharing because of their higher memory transaction overheads and thus higher false sharing penalties. In this paper we develop a dynamic-granularity shared memory management scheme that eliminates false sharing without sacrificing the transparency to conventional shared-memory applications. Our approach utilizes a special threaded splay tree (TST) for shared memory information management, and a dynamic token-based path-compression synchronization algorithm for data transferring. The combination of the TST and path compression is quite efficient;asymptotically, in an n-processor system with shared memory segments, synchronizing at most s segments takes O(s log m log n) amortized computation steps and generates O(s log n) communication messages, respectively. Based on the proposed scheme we constructed an experimental DSM prototype which consists of several Ethernet-connected Pentium-based computers running Linux. Preliminary benchmark results on our prototype indicate that our scheme is quite efficient, significantly outperforming traditional schemes and scaling up well.
The fourth industrial revolution (Industry 4.0) and its requirements impose radical changes to the underlying networking technologies that will be adopted in future factories. Most popular solutions in use today, in f...
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The fourth industrial revolution (Industry 4.0) and its requirements impose radical changes to the underlying networking technologies that will be adopted in future factories. Most popular solutions in use today, in fact, are suitable for Industry 4.0 only in part, and new techniques and devices have to be developed to cope with demanding needs in terms of flexibility, communication bandwidth, real-time behavior, mobility, scalability, energy efficiency, reliability, availability and security. The goal of this paper is assessing the current situation of factory communication systems in the light of their evolution to support Industry 4.0 applications. The paper provides an overview of fundamental concepts in factory communication systems focusing, in particular, on prevalent wireless and wirebound communication protocols and standards. Research challenges in next generation industrial networks are also taken into account.
Time synchronization technology is the key support technology of wireless sensor *** is the core mechanism to ensure the cooperation of nodes in sensor *** traditional time synchronization algorithm is not suitable fo...
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Time synchronization technology is the key support technology of wireless sensor *** is the core mechanism to ensure the cooperation of nodes in sensor *** traditional time synchronization algorithm is not suitable for wireless sensor *** on the analysis of the current situation of wireless sensor network time synchronization technology at home and abroad,this paper summarizes a variety of new time synchronization protocols based on scheduling time synchronization,mixed time synchronization and distributed time ***,the development trend of time synchronization technology is prospected.
Multiplayer online 3D games are becoming very popular in recent years. However, existing games require the complete game content to be installed prior to game playing. Since the content is usually large in size, it ma...
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ISBN:
(纸本)9781581139075
Multiplayer online 3D games are becoming very popular in recent years. However, existing games require the complete game content to be installed prior to game playing. Since the content is usually large in size, it may be difficult to run these games on a PDA or other handheld devices. It also pushes game companies to distribute their games as CDROMs/DVDROMs rather than online downloading. On the other hand, due to network latency, players may perceive discrepant status of some dynamic game objects. In this paper, we present a game-on-demand (GameOD) framework to distribute game content progressively in an on-demand manner. It allows critical contents to be available at the players' machines in a timely fashion. We present a simple distributed synchronization method to allow concurrent players to synchronize their perceived game status. Finally, we show some performance results of the proposed framework.
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