116,786 research outputs found
Fully pipelined bloom filter architecture
No full textRecently, we proposed a two-stage pipelined Bloom filter architecture to save power for network security applications. In this letter, we generalize the pipelined Bloom filter architecture to k-stage and show that significant power savings can be achieved by employing one hash function per stage. We analytically show that the expected power consumption and latency of the fully pipelined Bloom filter architecture will not be greater than that of the two hash functions and two clock cycles, respectively, however large the number of hash functions is. Furthermore, we discuss the worst-case performance of the proposed architecture.Recently, we proposed a two-stage pipelined Bloom filter architecture to save power for network security applications. In this letter, we generalize the pipelined Bloom filter architecture to k-stage and show that significant power savings can be achieved by employing one hash function per stage. We analytically show that the expected power consumption and latency of the fully pipelined Bloom filter architecture will not be greater than that of the two hash functions and two clock cycles, respectively, however large the number of hash functions is. Furthermore, we discuss the worst-case performance of the proposed architectur
Low-power bloom filter architecture for deep packet inspection
No full textBloom filters are frequently used to identify malicious content like viruses in high speed networks. However, architectures proposed to implement bloom filters are not power efficient. In this letter, we propose a new bloom filter architecture that exploits the well-known pipelining technique. Through power analysis we show that pipelining can reduce the power consumption of bloom filters up to 90%, which leads to the energy-efficient implementation of intrusion detection systems
Energy-efficient pipelined bloom filters for network intrusion detection
No full textSoftware-based detection techniques are commonly used to identify the predefined signatures in network streams. However, the software-based techniques can not keep up with the speeds that network bandwidth increases. Hence, hardware-based systems have started to emerge. Bloom filters are frequently used to identify malicious content like viruses in high speed networks. However, architectures proposed to implement Bloom filters are not power efficient. We propose a new Bloom filter architecture that exploits the well-known pipelining technique. Through extensive power analysis we show that pipelining can reduce the power consumption of Bloom filters up to 90%, which leads to the energy-efficient implementation of network intrusion detection system
The Madagascar Bloom – a serendipitous study
No full textThe late austral summer (February-April) phytoplankton bloom that occurs east of Madagascar exhibits significant interannual variability and at its largest extent covers ~1% of the world’s ocean surface area. The bloom raises many intriguing questions about how it begins, is sustained, propagates to the east, exports carbon and ends. It has been observed and studied using satellite ocean color observations, but the lack of in situ data makes it difficult to address these questions. Here we describe observations that were made serendipitously on a cruise in February 2005. These show clearly for the first time the simultaneous existence of a deep chlorophyll maximum at ~70-110 m depths (seen in SeaSoar fluorimeter data) and a surface chlorophyll signature (seen in SeaWiFS satellite ocean color data). The observations also show the modulation of biological signature at the surface by the eddy field, but not of the deep chlorophyll maximum. Trichodesmium dominates the bloom nearer to Madagascar, while the diatom Rhizosolenia clevei (and its symbiont Richelia intracellularis) dominates further from the island. The surface bloom seen in the SeaWiFS data is confined to the shallow (~30 m) mixed layer. It is hypothesized that the interannual variability in bloom intensity may be due to variations in coastal upwelling and thus the supply of iron, which is a micronutrient that can limit diazotroph growth
Increasing the power efficiency of Bloom filters for network string matching
No full textAlthough software based techniques are widely accepted in computer security systems, there is a growing interest to utilize hardware opportunities in order to compensate for the network bandwidth increases. Recently, hardware based virus protection systems have started to emerge. This type of hardware systems work by identifying the malicious content and removing it from the network streams. In principle, they make use of string matching. Bit by bit, they compare the virus signatures with the bit strings in the network. The bloom filters are ideal data structures for string matching. Nonetheless, they consume large power when many of them used in parallel to match different virus signatures. In this paper, we propose a new type of Bloom filter architecture which exploits well-known pipelining techniqu
Physical controls and mesoscale variability in the Labrador Sea spring phytoplankton bloom observed by Seaglider
No full textWe investigated the 2005 spring phytoplankton bloom in the Labrador Sea using Seaglider, an autonomous underwater vehicle equipped with hydrographic, bio-optical and oxygen sensors. The Labrador Sea blooms in distinct phases, two of which were observed by Seaglider: the north bloom and the central Labrador Sea bloom. The dominant north bloom and subsequent zooplankton growth are enabled by the advection of low-salinity water from West Greenland in the strong and eddy-rich separation of the boundary current. The glider observed high fluorescence and oxygen supersaturation within haline-stratified eddy-like features; higher fluorescence was observed at the edges than centers of the eddies. In the central Labrador Sea, the bloom occurred in thermally stratified water. Two regions with elevated subsurface chlorophyll were also observed: a 5 m thin-layer in the southwest Labrador Current, and in the Labrador shelf-break front. The thin layer observations were consistent with vertical shearing of an initially thicker chlorophyll patch. Observations at the front showed high fluorescence down to 100 m depth and aligned with the isopycnals defining the front. The high-resolution Seaglider sampling across the entire Labrador Sea provides first estimates of the scale dependence of coincident biological and physical variables
Mrs. Oscar T. Bloom
No full textOla Jessie Bloom, (Mrs. Oscar T. Bloom), of 2101 Hurley, new reagent of the Six Flags Chapter, Daughters of the American Resolution (DAR), was installed at Ernest Allen Ranch. She succeeded Mrs. W. C. Deaigh.https://mavmatrix.uta.edu/specialcollections_startelegram1950s/3692/thumbnail.jp
Let the Tree Bloom: Scalable Opportunistic Routing with ORPL
No full textRouting in battery-operated wireless networks is challenging, posing a tradeoff between energy and latency. Previous work has shown that opportunistic routing can achieve low-latency data collection in duty-cycled networks. However, applications are now considered where nodes are not only periodic data sources, but rather addressable end points generating traffic with arbitrary patterns.
We present ORPL, an opportunistic routing protocol that supports any-to-any, on-demand traffic. ORPL builds upon RPL, the standard protocol for low-power IPv6 networks. By combining RPL's tree-like topology with opportunistic routing, ORPL forwards data to any destination based on the mere knowledge of the nodes' sub-tree. We use bitmaps and Bloom filters to represent and propagate this information in a space-efficient way, making ORPL scale to large networks of addressable nodes. Our results in a 135-node testbed show that ORPL outperforms a number of state-of-the-art solutions including RPL and CTP, conciliating a sub-second latency and a sub-percent duty cycle. ORPL also increases robustness and scalability, addressing the whole network reliably through a 64-byte Bloom filter, where RPL needs kilobytes of routing tables for the same task
Valuation of Marine Ecosystem Threshold Effects : Application of Choice Experiments to Value Algal Bloom in the Black Sea Coast of Bulgaria
No full textAlgal bloom arises in part from anthropogenic emissions of nutrients into the coastal zone. Increased interest in water quality in coastal and marine areas stemming from the Water Framework Directive and the Marine Strategy Framework Directive leads to important questions in terms of policies to address nutrient loadings. This paper presents the results from a choice experiment for the valuation of algal blooms in Varna Bay, Bulgaria. Varna Bay is an important tourist destination and a large port city on the Black Sea coast of Bulgaria. Algal bloom events have been experienced frequently in this area. A choice experiment questionnaire was developed to be applied in Varna Bay. The key attributes used were visibility, duration of bloom and the amount of congestion on the beach. The amount of bloom is found to be important - respondents are willing to pay for a program that entails 1 week of algal bloom about 33 Leva (s.e. 8.09) when there is high visibility; 21 Leva (s.e. 5.75) with medium visibility and 9 Leva (s.e. 3.48) with low visibility. Respondents are willing to pay more for programs that offer shorter duration of algal bloom. The marginal price for one metre of extra space between the respondent and the nearest person is equal to 0.38 Leva.threshold effects; marine ecosystem
Redbud tree in full bloom, Glen Canyon river trip
No full textColor slide photograph by Fred T. Darvill taken during a river trip through Glen Canyon on April 23-27, 1959. The trip was led by Jack Brennan and Don Harris of Harris-Brennan Expeditions. This photo shows a redbud tree in full bloom in Glen Canyon
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