3,033 research outputs found
FLASH: Randomized Algorithms Accelerated over CPU-GPU for Ultra-High Dimensional Similarity Search
We present FLASH (\textbf{F}ast \textbf{L}SH \textbf{A}lgorithm for
\textbf{S}imilarity search accelerated with \textbf{H}PC), a similarity search
system for ultra-high dimensional datasets on a single machine, that does not
require similarity computations and is tailored for high-performance computing
platforms. By leveraging a LSH style randomized indexing procedure and
combining it with several principled techniques, such as reservoir sampling,
recent advances in one-pass minwise hashing, and count based estimations, we
reduce the computational and parallelization costs of similarity search, while
retaining sound theoretical guarantees.
We evaluate FLASH on several real, high-dimensional datasets from different
domains, including text, malicious URL, click-through prediction, social
networks, etc. Our experiments shed new light on the difficulties associated
with datasets having several million dimensions. Current state-of-the-art
implementations either fail on the presented scale or are orders of magnitude
slower than FLASH. FLASH is capable of computing an approximate k-NN graph,
from scratch, over the full webspam dataset (1.3 billion nonzeros) in less than
10 seconds. Computing a full k-NN graph in less than 10 seconds on the webspam
dataset, using brute-force (), will require at least 20 teraflops. We
provide CPU and GPU implementations of FLASH for replicability of our results
Study of large solar flares in association with halo Coronal Mass Ejections and their helio-longitudinal association with Forbush decreases of cosmic rays
Percentile Data Analysis of Snowfall in J&K and Saichen Glaciers Region
The Indian Himalayas are located between eastings 72° to 96° and the northings 26° to 37°stretching to about 43000 km2 area. There are five major ranges in this region, ie, Pir Panjal,Greater Himalayas, Zanskar, Laddakh, and Karakoram. Saltoro range is the major branch ofwidespread Karakoram ranges which falls in Indian territory. Saichen glaciers are located inSaltoro range. Percentile data of snowfall gives first-hand information about the snowfall patternin Jammu and Kashmir and Saichen glaciers, the two distinguished areas of Indian Himalayaswhich would help in prediction of avalanche activity in these areas. Western disturbanceoriginating from Caspian sea basically dictates the weather condition in this region. Westerndisturbance approaches from western side and hits Pir Panjal range and Greater Himalayan rangefirst, and then either it moves to further north or towards north-eastern region. Westerndisturbance yields maximum precipitation during winter season over north-west Himalayas, butas it moves further, it looses the moisture content, hence reducing the solid snowfall quantitybut stays for a longer duration due to extremely low temperatures observed in the region ofSaichen glaciers. The data analysis shows that the snowfall takes place in Saichen glacierthroughout the year whereas in Jammu and Kashmir area, snowfall takes place only during winterseason. Change in snowfall pattern in these two regions is attributed to the variation intemperature in these regions, movement of weather system, and the difference in altitude. In thepresent study, four locations at varied altitudes from Jammu and Kashmir area and the completeSaichen glaciers region have been covered to analyse the snowfall pattern for the period from1995-2000
Short-term influence of high speed solar wind streams on cosmic ray intensity variation during 1996-2002
Flurbiprofen- and Suprofen-Dextran Conjugates: Synthesis, Characterization and Biological Evaluation
Purpose: To synthesize and characterize the dextran conjugates of suprofen and flurbiprofen, and also evaluate their biological activities.Methods: Suprofen and flurbiprofen were individually reacted with carbonyldiimidazole to form acylimidazole, which, in turn, was reacted with the dextran of varying molecular weight (40 000, 60 000, and 110 000) to form drug-dextran conjugates. The structures of the synthesized dextran conjugates were confirmed by IR and NMR spectroscopy. In vitro hydrolysis of the conjugates were studied in buffer solutions (pH 7.4 and 9.0) and 80% human plasma (pH 7.4). The analgesic and antipyretic activities, aswell as the ulcerogenic index of the conjugates were also evaluated in albino rats.Results: The mean degree of substitution of flurbiprofen and suprofen was between 8.0 to 9.5 % and 7.5 to 9.0 %, respectively. In vitro hydrolysis studies on the conjugates indicate faster hydrolysis at pH9.0 than in pH 7.4 buffer solution and 80% human plasma (pH 7.4) with the process following First order kinetics. The analgesic activity of flurbiprofen-dextran conjugate (FD-110) suprofen-dextran conjugate(SD-110) was 64.23 and 41.50% which compare well with those of their parent drugs - flurbiprofen (72.60%) and suprofen (44.30%). Similar findings were made in respect of the antipyretic activity. Bothflurbiprofen and suprofen showed deep ulceration, swelling and high intensity perforation in the gastric mucosa after seven days administration of flurbiprofen and suprofen with the ulcerogenic indices of29.69 and 31.0 respectively, cpmpare with 5.88 and 6.06 for FD-110 and SD-110, respectively.Conclusion: Dextran can be employed as a pro-moiety or carrier for the delivery of flurbiprofen and suprofen and showed comparable analgesic and antipyretic activities with the parent drugs but with lower ulcerogenic indices
Cosmic ray intensity distribution perpendicular to solar equatorial plane at 1 A.U. during 1978-83
The distribution of cosmic ray intensity perpendicular to solar equatorial plane, was investigated by using its yearly variation with respect to the heliolatitudinal position of the Earth, for the two intervals 1978 to 1980 and 1981 to 1983. The monthly mean values of two high latitude stations along with the solar and geomagnetic indices are used to derive the cosmic ray intensity distribution free from the changes due to variation in solar activity. The correction is found to be significant only during the interval 1976 to 1980. The results indicate a significant linear increase in cosmic ray intensity from north to south of solar equator, contrary to that observed during 1973 to 1975. No symmetrical gradients are found during the period of study, in agreement with earlier results
Role of solar flare index in long term modulation of cosmic ray intensity
Recently, the importance of the occurrence of solar flares in the long-term modulation of cosmic ray intensity has been re-emphasized. For this purpose, the data of solar flares have been used from various publications, such as Solar Geophysical Data books, U.A.G. reports and Quarterly Bulletin Of Solar Activity. Research very clearly reveals that even the periodic changes in the solar flare observations, obtained from the four different data sources, for the same interval, differ significantly from one another; this is evidenced even on an average basis. Hence, in any study using solar flares, the importance of selecting a single compilation of the solar-flare data for the entire period of investigation is stressed
Effects of joint rate and displacement constraints on stability regions
A block diagram showing plant dynamics in normal mode coordinates, a linear feedback controller with command limits, and actuator dynamics with rate and displacement limits is given. The objective is to examine the effects of joint rate and displacement saturation limits on the stability regions. An unstable short period dynamic model is transformed into normal mode coordinates and is augmented with actuator dynamics. A linear feedback controller is used to provide closed-loop stability. The stability with constrained actuator rate limits under varying bandwidth, displacement and command limits is examined
Asynchronous Message Transmission Technique for Latency Requirements in Time Critical Ship-borne System
A solution to data ageing requirements in time critical ship system like fire control system is presented. In an operational sea borne platform, navigation requirements for the onboard systems are fulfilled by ring laser gyro-based inertial navigation system. For critical systems like fire control system, navigational data must be delivered in real time without any delay. However due to delay occurring in processing of raw information and transmission of data on interface bus some latency is introduced. Algorithm for an asynchronous message transmission technique from inertial navigation system to user system to meet its latency requirements is discussed. Latency requirement is achieved by sending a separate message with the time stamp for the instance the first byte of 100 Hz attitude data is received at the processing computer of navigation system.
Structural, electronic and elastic properties of RERu2 (RE = Pr, Nd and Sm) Laves phase compounds
Bonding nature, structural, electronic, magnetic and elastic properties of RERu2 (RE = Pr, Nd and Sm) Laves phase compounds have been studied using the full-potential linearized augmented plane wave (FP-LAPW) method based on density functional theory. The LSDA and LSDA+U approach has been used to get accurate results because of the presence of the highly localized 4f electron of RE (RE = Pr, Nd and Sm) atoms. The calculated lattice parameters and magnetic moments are in good agreement with available experimental results. The electronic and bonding properties have been resolved in terms of band structures, DOS, Fermi surfaces and charge density difference plots, which confirm their metallic character. From the charge density difference plots it has been observed that these compounds show mixed covalent-ionic bonding nature simultaneously and metallic bonding is also present. The mechanical properties and Debye temperature have been predicted from the calculated elastic constants. The ductility of these Laves phase compounds have been predicted in accordance with Pugh’s criteria
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