Approximate similarity search for online multimedia services on distributed CPU–GPU platforms

Similarity search in high-dimensional spaces is a pivotal operation for several database applications, including online content-based multimedia services. With the increasing popularity of multimedia applications, these services are facing new challenges regarding (1) the very large and growing volumes of data to be indexed/searched and (2) the necessity of reducing the response times as observed by end-users. In addition, the nature of the interactions between users and online services creates fluctuating query request rates throughout execution, which requires a similarity search engine to adapt to better use the computation platform and minimize response times. In this work, we address these challenges with Hypercurves, a flexible framework for answering approximate k-nearest neighbor (kNN) queries for very large multimedia databases. Hypercurves executes in hybrid CPU–GPU environments and is able to attain massive query-processing rates through the cooperative use of these devices. Hypercurves also changes its CPU–GPU task partitioning dynamically according to the observed load, aiming for optimal response times. In our empirical evaluation, dynamic task partitioning reduced query response times by approximately 50 % compared to the best static task partition. Due to a probabilistic proof of equivalence to the sequential kNN algorithm, the CPU–GPU execution of Hypercurves in distributed (multi-node) environments can be aggressively optimized, attaining superlinear scalability while still guaranteeing, with high probability, results at least as good as those from the sequential algorithm.     

The feasibility of general task systems with precedence constraints on multiprocessor platforms

Feasibility analysis determines (prior to system execution-time) whether a specified collection of hard-real-time jobs executed on a processing platform can meet all deadlines. In this paper, we derive near-optimal sufficient tests for determining whether a given collection of jobs can feasibly meet all deadlines upon a specified multiprocessor platform assuming job migration is permitted. The collection of jobs may contain precedence constraints upon the order of execution of these jobs. The derived tests are general enough to be applied even when the collection of jobs is incompletely specified. We discuss the applicability of these tests to the scheduling of collections of jobs that are generated by systems of recurrent real-time tasks. We also show that our feasibility conditions may be used to obtain global-EDF schedulability conditions.

Nonlinear ultimate boundedness control and stabilization of a flexible robotic arm

We treat the question of control of an elastic robotic arm of two links. Of course, this approach can be extended to other elastic arms. A nonlinear ultimate boundedness controller (UBC) is synthesized such that in the closed-loop system the joint angle tracking error is uniformly bounded and tends to a certain small neighborhood of the origin. The controller includes a reference joint angle trajectory generator and integral error feedback. Although the joint angles are controlled using the UBC, elastic modes are excited. A feedback stabilizer is designed for the linearized model including the UBC about the terminal state that is switched only in the vicinity of the equilibrium state for stabilization. Simulation results are presented to show that in the closed-loop system including the UBC and the stabilizer accurate joint angle trajectory following and elastic mode stabilization are accomplished in the presence of uncertainty.     

Outcomes of treatment for alcohol problems: Current methods, problems, and results.

This overview of current methods, problems, and results of psychological treatment for alcohol abuse, including alcoholism, begins by considering three common and troublesome assumptions about such treatment. A discussion of external and internal validity problems that are specific to alcoholism treatment research follows, and promising solutions are reviewed. Current data are discussed on who is treated for alcohol problems in this country. Next, detailed consideration is given to factors that predict response to alcoholism treatment, including variables associated with treatment type, setting, and intensity; such factors specific to patients as age, gender, ethnicity, socioeconomic status and education, psychopathology, marital and occupational status, and motivation for change; and environmental and other extratreatment factors. The article concludes with a review of current data on nonproblem-drinking treatment goals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Small-Signal Dynamic Analysis of Regulated Class E DC/DC Converters

Class E dc/dc converters can operate at high switching frequencies with very low switching power losses. Using commercially available power transistors and diodes, Class E converters can operate at switching frequencies in the low-MHz range, with efficiencies of about 85 percent. Previous papers dealt with the circuit parameter values needed to obtain high-efficiency operation and output-voltage regulation, and with the static control characteristics of the Class E dc/dc converter cell. The analysis is extended to include the dynamic control characteristics and further information about the static characteristics. The theoretical predictions are verified by experimental measurements on a 40-W 1.5-MHz converter.     

Noise correlation in dual-collector magnetotransistors

Experimental results of low frequency (1/f) noise in magnetic-field-sensitive dual-collector bipolar transistors are presented that show a strong positive correlation between the noise voltages (converted from corresponding fluctuations in the currents) of the collectors. Hence, operating the magnetotransistor in a differential mode yields very favorable signal-to-noise ratios, even for low magnetic sensitivity. Calculations performed for a magnetotransistor with a sensitivity of only 0.06/T yields a field resolution of 25 nT/√Hz at 1 kHz, in contrast to 14 μT/√Hz in single-ended operation     

Benzophenone vs. Copper/Benzophenone in Light‐Promoted Atom Transfer Radical Additions (ATRAs): Highly Effective Iodoperfluoroalkylation of Alkenes/Alkynes and Mechanistic Studies

Iodoperfluooralkylation of terminal alkenes and alkynes is effectively photo‐promoted by benzophenone 2 (BP) or the photoreducible copper(II) complex 1 . In particular, BP at 1 mol% in methanol upon 365 nm irradiation with a low‐pressure mercury lamp (type TLC=thin layer chromatography, 6 W) results in a fast reaction with excellent reaction yields. Complex 1 and BP 2 exhibited very similar reactivity, suggesting that the reactions involving 1 are likely to be governed by the benzophenone photoactivation processes, rather than copper(I)/(II) redox processes. Mechanistic investigations using transient absorption spectroscopy revealed that a deactivation pathway of the benzophenone triplet (³BP*) is via its reaction with the methanol solvent. We propose that the generated radicals, in particular ^.CH₂OH, play a key role in the initiation step forming R_f^. by reacting with R_fI, R_f^. then entering a radical chain cycle. ¹H NMR studies provided evidence that a substantial amount (∼7% NMR yield) of the hemiacetal CH₃OCH₂OH is formed, i.e., the possible by‐product of the reaction between ^.CH₂OH and R_fI. Finally, DFT calculations indicate that a triplet‐triplet energy transfer (TTET) process from ³BP* to perfluorooctyl iodide (C₈F₁₇I) is unlikely or should be rather slow under the reaction conditions, consistent with the transient absorption studies.

     

Anxiety and the variability of word associates.

15 Ss who scored high on the Taylor MA scale and 15 Ss who scored low on the MA scale were given a word associate task. The highly anxious Ss tended to have sets of word associates lower in intersubject variability than the nonanxious Ss for stimulus words that elicited sets of word associates that are low in variability. Highly anxious Ss tended to give sets of word associates higher in intersubject variability than nonanxious Ss for stimulus words that elicited sets of word associates that are high in intersubject variability. A 2nd experiment reports data indicating a relationship between inter- and intrasubject variability of word associates. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Simultaneous measurement of the surface temperature and the release of atomic sodium from a burning black liquor droplet

Simultaneous measurement of the concentration of released atomic sodium, swelling, surface and internal temperature of a burning black liquor droplet under a fuel lean and rich condition has been demonstrated. Two-dimensional two-colour optical pyrometry was employed to determine the distribution of surface temperature and swelling of a burning black liquor droplet while planar laser-induced fluorescence (PLIF) was used to assess the temporal release of atomic sodium. The key findings of these studies are: (i) the concentration of atomic sodium released during the drying and devolatilisation stages was found to be correlated with the external surface area; and (ii) the insignificant presence of atomic sodium during the char consumption stage shows that sodium release is suppressed by the lower temperature and by the high CO₂ content in and around the particle.