In this work, for a wireless sensor network (WSN) of n randomly placed sensors with node density \lambda \in [1,n], we study the tradeoffs between the aggregation throughput and gathering efficiency. The gathering eff...
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In this work, for a wireless sensor network (WSN) of n randomly placed sensors with node density \lambda \in [1,n], we study the tradeoffs between the aggregation throughput and gathering efficiency. The gathering efficiency refers to the ratio of the number of the sensors whose data have been gathered to the total number of sensors. Specifically, we design two efficient aggregation schemes, called single-hop-length (SHL) scheme and multiple-hop-length (MHL) scheme. By novelly integrating these two schemes, we theoretically prove that our protocol achieves the optimal tradeoffs, and derive the optimal aggregation throughput depending on a given threshold value (lower bound) on gathering efficiency. Particularly, we show that under the MHL scheme, for a practically important set of symmetric functions called divisible perfectly compressible (DPC) functions, including the mean, max, and various kinds of indicator functions, etc., the data from \Theta (n) sensors can be aggregated to the sink at the throughput of a constant order \Theta (1), implying that, our MHL scheme is indeed scalable.
A terrain data organization method was proposed in this article in order to solve large scale data realtime rendering problem, which combines wavelet transform and quadtree to organize the terrain data, to further bui...
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Dawning Nebulae is a heterogeneous system composed of 9280 multi-core x86 CPUs and 4640 NVIDIA Fermi GPUs. With a Linpack performance of 1.271 petaFLOPS, it was ranked the second in the TOP500 List released in June 20...
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Dawning Nebulae is a heterogeneous system composed of 9280 multi-core x86 CPUs and 4640 NVIDIA Fermi GPUs. With a Linpack performance of 1.271 petaFLOPS, it was ranked the second in the TOP500 List released in June 2010. In this paper, key issues in the system design of Dawning Nebulae are introduced. system tuning methodologies aiming at petaFLOPS Linpack result are presented, including algorithmic optimization and communication improvement. The design of its file I/O subsystem, including HVFS and the underlying DCFS3, is also described. Performance evaluations show that the Linpack efficiency of each node reaches 69.89%, and 1024-node aggregate read and write bandwidths exceed 100 GB/s and 70 GB/s respectively. The success of Dawning Nebulae has demonstrated the viability of CPU/GPU heterogeneous structure for future designs of supercomputers.
With the continual scaling of semiconductor process technology, the circuit timing is increasingly impacted by process variations. It is thus important to categorize high-speed digital circuits into multiple bins of d...
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With the continual scaling of semiconductor process technology, the circuit timing is increasingly impacted by process variations. It is thus important to categorize high-speed digital circuits into multiple bins of different performances. However, the speed-binning process typically needs very long test application time. In this paper, we proposed a unified architecture, which can accomplish performance grading with a high confidence and short test application time. Moreover, the proposed architecture can be used for on-line circuit failure prediction and detection. Experimental results are presented to validate the proposed architecture.
NAND Flash memories have rapidly emerged as a storage class memory such as SSD (Solid State Disk), CF (Compact Flash) Card, SD (Secure Digital Memory) Card. Due to its distinct operation mechanisms, NAND Flash memory ...
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NAND Flash memories have rapidly emerged as a storage class memory such as SSD (Solid State Disk), CF (Compact Flash) Card, SD (Secure Digital Memory) Card. Due to its distinct operation mechanisms, NAND Flash memory suffers from erase/program endurance, data retention and program/read disturbance problems. Specifically, erase and program operation keeps in developing bad blocks during the lifetime of memory chips. Bad blocks are blocks that contain faulty bits but the ECC (Error Correction Code) algorithm cannot correct them. Although wear leveling tries to balance the erase/program operations on different blocks so that all blocks can wear out at a similar pace, new bad blocks still inevitably *** propose an in-field testing technique which takes some pages in a block as predictors. Due to wear out faster than the other pages, the predictors will become bad before the other pages in the block become bad. The further questions are (1) how to detect those wearing fast pages so as to use them as predictors, (2) how many predictors are needed to achieve a satisfactory prediction accuracy, (3) misprediction will result in what negative impact on performance and endurance.
ADML is an architectural description language based on Dynamic Description Logic for defining and simulating the behavior of systemarchitecture. ADML is being developed as a new formal language and/or conceptual mode...
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Due to advances in low power micro-sensor technology, energy harvesting techniques, we can now build large scale solar-powered sensor networks to support long-running operations. Solar powered sensors often harvest va...
Due to advances in low power micro-sensor technology, energy harvesting techniques, we can now build large scale solar-powered sensor networks to support long-running operations. Solar powered sensors often harvest variable amounts of energy in different weather conditions. Then a primary requirement for an efficient and a long-running solar-powered sensor system is to adapt to changing environment conditions and resources, and to gather as much valuable data as possible. Sensing and collecting data at a constant rate, without taking into account energy availability or data deliverability, will either drain the battery or waste resources. In this work, we design and test a highly efficient and robust solar-powered system SmartMote; and we further present an energy and value of information (VoI) aware routing strategy, that balances the rates of sensing with packet delivery for SmartMote. SmartMote achieves fairness and near maximum utility across the network. We deploy SmartMote in a forest with 100 sensors in order to monitor the humidity, temperature and luminance intensity. Our experimental results corroborate our design.
In this paper, we study multicast capacity for cognitive networks. We consider the cognitive network model consisting of two overlapping ad hoc networks, called the primary ad hoc network (PaN) and secondary ad hoc ne...
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In this paper, we study multicast capacity for cognitive networks. We consider the cognitive network model consisting of two overlapping ad hoc networks, called the primary ad hoc network (PaN) and secondary ad hoc network (SaN), respectively. PaN and SaN operate on the same space and spectrum. For PaN (or SaN, respectively), we assume that primary (or secondary, respectively) nodes are placed according to a Poisson point process of intensity n (or m, respectively) over a unit square region. We randomly choose n s (or m s , respectively) nodes as the sources of multicast sessions in PaN (or SaN, respectively), and for each primary source vp (or secondary source v s , respectively), we pick uniformly at random nd primary nodes (or md secondary nodes, respectively) as the destinations of v p (or v s , respectively). Above all, we assume that PaN can adopt the optimal protocol in terms of the throughput. Our main work is to design the multicast strategy for SaN by which the optimal throughput can be achieved, without any negative impact on the throughput for PaN in order sense. Depending on nd and n, we choose the optimal one for PaN from two strategies called percolation strategy and connectivity strategy, respectively. Subsequently, we design the corresponding throughput-optimal strategy for SaN. We derive the regimes in terms of n, n d , m, and m d in which the upper bounds on multicast capacities for PaN and SaN can be achieved simultaneously. Unicast and broadcast capacities for the cognitive network can be derived by our results as the special cases by letting n d = 1 (or m d = 1) and n d = n - 1 (or m d = m - 1), respectively, which enhances the generality of this work.
IEEE 802.15.4/ZigBee sensor networks support small power consumption and node expansion compared to other network standards for WSN. Body sensor networks (BSN) require a number of sensors for sensing medical informati...
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IEEE 802.15.4/ZigBee sensor networks support small power consumption and node expansion compared to other network standards for WSN. Body sensor networks (BSN) require a number of sensors for sensing medical information from human body, and low power consumption to monitor a patient's status for a long time. However, ZigBee has limited bandwidth and is thus hard to support real time data transmission because of the adoption of CSMA-CA as its medium access control (MAC) protocol. In this paper, we will analyze the reasonable number of nodes, size of payload and packet interval for best QoS for such network. It is found that an appropriate MAC parameters setting can improve the QoS compared to the default setting in IEEE 802.15.4 specification. The effective data rate, average end-to-end delay and packet delivery ratio are found via simulation for various network settings. The results are useful for the construction of ZigBee networks for patient monitoring and care.
We study the asymptotic throughput for a large-scale wireless ad hoc network consisting of n nodes under the generalized physical model. We directly compute the throughput of multicast sessions to unify the unicast an...
We study the asymptotic throughput for a large-scale wireless ad hoc network consisting of n nodes under the generalized physical model. We directly compute the throughput of multicast sessions to unify the unicast and broadcast throughputs. We design two multicast schemes based on the so-called ordinary arterial road system and parallel arterial road system, respectively. Correspondingly, we derive the achievable multicast throughput by taking account of all possible cases of n
s
= ω(1) and 1 ≤ n
d
≤ n − 1, rather than only the cases of
$$n_s=\Uptheta(n)$$
as in most related works, where n
s
and n
d
denote the number of sessions and the number of destinations of each session, respectively. Furthermore, we consider the network with a general node density
$$\lambda \in [1,n]$$
, while the models in most related works are either random dense network (RDN) or random extended network (REN) where the density is λ = n and λ = 1, respectively, which further enhances the generality of this work. Particularly, for the special case of our results by letting λ = 1 and
$$n_s=\Uptheta(n)$$
, we show that for some regimes of n
d
, the multicast throughputs achieved by our schemes are better than those derived by the well-known percolation-based schemes.
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