scholarly journals ALGORITHMS FOR HIGH PERFORMANCE, WIDE-AREA DISTRIBUTED FILE DOWNLOADS

2003 ◽  
Vol 13 (02) ◽  
pp. 207-223 ◽  
Author(s):  
JAMES S. PLANK ◽  
SCOTT ATCHLEY ◽  
YING DING ◽  
MICAH BECK

As peer-to-peer and wide-area storage systems become in vogue, the issue of delivering content that is cached, partitioned and replicated in the wide area, with high performance, becomes of great importance. This paper explores three algorithms for such downloads. The storage model is based on the Network Storage Stack, which allows for flexible sharing and utilization of writable storage as a network resource. The algorithms assume that data is replicated in various storage depots in the wide area, and the data must be delivered to the client either as a downloaded file or as a stream to be consumed by an application, such as a media player. The algorithms are threaded and adaptive, attempting to get good performance from nearby replicas, while still utilizing the faraway replicas. After defining the algorithms, we explore their performance downloading a 50 MB file replicated on six storage depots in the U.S., Europe and Asia, to two clients in different parts of the U.S. One algorithm, called progress-driven redundancy, exhibits excellent performance characteristics for both file and streaming downloads.

1998 ◽  
Vol 61 (6) ◽  
pp. 704-707 ◽  
Author(s):  
MAURICIO M. CASTELO ◽  
SUSAN S. SUMNER ◽  
LLOYD B. BULLERMAN

Corn-based food products obtained from commercial outlets in three different parts of the U.S., Maryland, Nebraska, and Arizona were analyzed for total fumonisins by a commercial competitive direct enzyme-linked immunosorbant assay (CD-ELISA) and for fumonisin B1 (FB1) by high-performance liquid chromatography (HPLC). The highest fumonisin concentrations were found in samples collected in Maryland, where all 18 samples were found positive for fumonisins (200 to 7,450 ng/g of food) by CD-ELISA and 15 of the 18 samples (83%) were found positive for FB1 (<75 to 5,916 ng/g) by HPLC. Fumonisins were also detected by CD-ELISA in 14 of 15 samples collected in Arizona, with concentrations ranging from 200 to 1,450 ng/g, but analyses by HPLC showed that only 8 of 15 samples (53%) were positive for FB1 (<75 to 1,565 ng/g of food). Of the 23 samples collected in Nebraska, 20 (87%) were positive for fumonisins (200 to 2,500 ng/g) by CD-ELISA, but only 10 (44%) were positive for FB1 (<75 to 927 ng/g) by HPLC. The highest fumonisin and FB1 concentrations were found in cornmeal samples, ranging up to 7,450 ng/g of cornmeal by CD-ELISA and 5,916 ng/g by HPLC. These findings indicate that there may be a risk of human exposure to fumonisins through the consumption of some corn-based foods.


2020 ◽  
Vol 12 (12) ◽  
pp. 31-43
Author(s):  
Tatiana A. VASKOVSKAYA ◽  
◽  
Boris A. KLUS ◽  

The development of energy storage systems allows us to consider their usage for load profile leveling during operational planning on electricity markets. The paper proposes and analyses an application of an energy storage model to the electricity market in Russia with the focus on the day ahead market. We consider bidding, energy storage constraints for an optimal power flow problem, and locational marginal pricing. We show that the largest effect for the market and for the energy storage system would be gained by integration of the energy storage model into the market’s optimization models. The proposed theory has been tested on the optimal power flow model of the day ahead market in Russia of 10000-node Unified Energy System. It is shown that energy storage systems are in demand with a wide range of efficiencies and cycle costs.


2021 ◽  
Vol 13 (16) ◽  
pp. 8789
Author(s):  
Giovanni Bianco ◽  
Barbara Bonvini ◽  
Stefano Bracco ◽  
Federico Delfino ◽  
Paola Laiolo ◽  
...  

As reported in the “Clean energy for all Europeans package” set by the EU, a sustainable transition from fossil fuels towards cleaner energy is necessary to improve the quality of life of citizens and the livability in cities. The exploitation of renewable sources, the improvement of energy performance in buildings and the need for cutting-edge national energy and climate plans represent important and urgent topics to be faced in order to implement the sustainability concept in urban areas. In addition, the spread of polygeneration microgrids and the recent development of energy communities enable a massive installation of renewable power plants, high-performance small-size cogeneration units, and electrical storage systems; moreover, properly designed local energy production systems make it possible to optimize the exploitation of green energy sources and reduce both energy supply costs and emissions. In the present paper, a set of key performance indicators is introduced in order to evaluate and compare different energy communities both from a technical and environmental point of view. The proposed methodology was used in order to assess and compare two sites characterized by the presence of sustainable energy infrastructures: the Savona Campus of the University of Genoa in Italy, where a polygeneration microgrid has been in operation since 2014 and new technologies will be installed in the near future, and the SPEED2030 District, an urban area near the Campus where renewable energy power plants (solar and wind), cogeneration units fed by hydrogen and storage systems are planned to be installed.


Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4386
Author(s):  
Muhammad Syahmi Abd Rahman ◽  
Mohd Zainal Abidin Ab Kadir ◽  
Muhamad Safwan Abd Rahman ◽  
Miszaina Osman ◽  
Shamsul Fahmi Mohd Nor ◽  
...  

The advancement of material technology has contributed to the variation of high-performance composites with good electrical insulation and mechanical properties. Their usage in electrical applications has grown since then. In Malaysia, the composite made of Glass Fiber Reinforced Polymer (GFRP) has been adopted for crossarm manufacturing and has successfully served 275 kV lines for a few decades. However, the combination of extreme conditions such as lightning transient and tropical climate can impose threats to the material. These issues have become major topics of discussion among the utilities in the Southeast Asian (SEA) region, and also in previous research. In Malaysia, more than 50% of total interruptions were caused by lightning. Limited studies can be found on the composite crossarm, especially on the square tube GFRP filled crossarm used in Malaysia. Therefore, this paper proposes to study the behavior of the particular GFRP crossarm, by means of its insulation characteristics. Experimental and simulation approaches are used. Throughout the study, the GFRP specimen is known to have an average breakdown strength at 7.2 kV/mm. In addition, the CFO voltages of the crossarm at different lengths are presented, whereby the behavior under dry and wet conditions is comparably discussed. At the same time, the polarity effect on the CFO voltages is highlighted. The maximum E-fields at the immediate moment before breakdown are analyzed by adopting the finite element method (FEM). Non-uniform distribution of E-fields is witnessed at different parts of the crossarm structure. Simultaneously, the maximum field localized on the crossarm immediately before the breakdown is also presented.


RSC Advances ◽  
2020 ◽  
Vol 10 (40) ◽  
pp. 23749-23758
Author(s):  
Yu Wang ◽  
Wangsheng Chen ◽  
Bo Zhao ◽  
Huaqin Wang ◽  
Linbo Qin ◽  
...  

A series of activated carbons were prepared by carbonizing sugarcane bagasse combined with surface modification, which showed an excellent performance of adsorbing toluene (522 mg g−1 at 30 °C).


2017 ◽  
Vol 5 (5) ◽  
pp. 2328-2338 ◽  
Author(s):  
Dewei Rao ◽  
Lingyan Zhang ◽  
Zhaoshun Meng ◽  
Xirui Zhang ◽  
Yunhui Wang ◽  
...  

Since the turn of the new century, the increasing demand for high-performance energy storage systems has generated considerable interest in rechargeable ion batteries.


Author(s):  
Dai Jiu Yi ◽  
Soram Bobby Singh ◽  
Nam Hoon Kim ◽  
Joong Hee Lee

The rational design of free-standing hierarchic core–shell nanoporous architectures is a good strategy for fabricating next-generation electrode materials for application to electrochemical energy conversion/storage systems. Herein, hierarchical core–shell 3D Co9S8@Nix:Moy–Se...


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