Conjunctions of Among Constraints

Many existing global constraints can be encoded as a conjunction of among constraints. An among constraint holds if the number of the variables in its scope whose value belongs to a prespecified set, which we call its range, is within some given bounds. It is known that domain filtering algorithms can benefit from reasoning about the interaction of among constraints so that values can be filtered out taking into consideration several among constraints simultaneously. The present pa- per embarks into a systematic investigation on the circumstances under which it is possible to obtain efficient and complete domain filtering algorithms for conjunctions of among constraints. We start by observing that restrictions on both the scope and the range of the among constraints are necessary to obtain meaningful results. Then, we derive a domain flow-based filtering algorithm and present several applications. In particular, it is shown that the algorithm unifies and generalizes several previous existing results.Comment: 15 pages plus appendi

Statistical Inference in a Directed Network Model with Covariates

Networks are often characterized by node heterogeneity for which nodes exhibit different degrees of interaction and link homophily for which nodes sharing common features tend to associate with each other. In this paper, we propose a new directed network model to capture the former via node-specific parametrization and the latter by incorporating covariates. In particular, this model quantifies the extent of heterogeneity in terms of outgoingness and incomingness of each node by different parameters, thus allowing the number of heterogeneity parameters to be twice the number of nodes. We study the maximum likelihood estimation of the model and establish the uniform consistency and asymptotic normality of the resulting estimators. Numerical studies demonstrate our theoretical findings and a data analysis confirms the usefulness of our model.Comment: 29 pages. minor revisio

Разработка системы импульсного питания сварной дуги с разделением токоподвода к изделию

Объектом исследования является: процесс сварки неплавящимся электродом в аргоне. Предмет исследования ? сварочная дуга горящая в импульсном режиме на постоянном токе. Цель работы ? является исследование и разработка системы импульсного питания сварной дуги с разделением токоподвода к изделию. В процессе исследования проводились анализ методов повышения эффективности и способы сварки неплавящимся электродом с применением импульсного питания сварочной дуги, проведен анализ сварки модулированным током и предложен наиболее перспективный способ. В результате исследования разработана принципиальная электрическая схема модулятора обеспечивающее двойной токоподвод к изделию.Object of research: the process of Non-consumable Electrode Arc welding in argon. Subject of research: welding arc burning in the pulsed mode at direct current. Purpose of research: is the research and development of a pulsed power supply system for a welded arc with the separation of the current lead to the product. In the process of the investigation, methods of increasing efficiency and methods for welding with a non-consumable electrode were analyzed using pulse welding arc welding, an analysis of modulated current welding was performed and the most promising method was proposed. Results of research: a basic electrical circuit of the modulator was developed to provide a double current lead to the product

Integrating the Fermi Gamma-Ray Burst Monitor into the 3rd Interplanetary Network

We are integrating the Fermi Gamma-Ray Burst Monitor (GBM) into the Interplanetary Network (IPN) of Gamma-Ray Burst (GRB) detectors. With the GBM, the IPN will comprise 9 experiments. This will 1) assist the Fermi team in understanding and reducing their systematic localization uncertainties, 2) reduce the sizes of the GBM and Large Area Telescope (LAT) error circles by 1 to 4 orders of magnitude, 3) facilitate the identification of GRB sources with objects found by ground- and space-based observatories at other wavelengths, from the radio to very high energy gamma-rays, 4) reduce the uncertainties in associating some LAT detections of high energy photons with GBM bursts, and 5) facilitate searches for non-electromagnetic GRB counterparts, particularly neutrinos and gravitational radiation. We present examples and demonstrate the synergy between Fermi and the IPN. This is a Fermi Cycle 2 Guest Investigator project.Comment: 5 pages, 11 figures. 2009 Fermi Symposium. eConf Proceedings C09112

The Interplanetary Network Supplement to the BeppoSAX Gamma-Ray Burst Catalogs

Between 1996 July and 2002 April, one or more spacecraft of the interplanetary network detected 787 cosmic gamma-ray bursts that were also detected by the Gamma-Ray Burst Monitor and/or Wide-Field X-Ray Camera experiments aboard the BeppoSAX spacecraft. During this period, the network consisted of up to six spacecraft, and using triangulation, the localizations of 475 bursts were obtained. We present the localization data for these events.Comment: 89 pages, 3 figures. Submitted to the Astrophysical Journal Supplement Serie

The ultraluminous GRB 110918A

GRB 110918A is the brightest long GRB detected by Konus-WIND during its 19 years of continuous observations and the most luminous GRB ever observed since the beginning of the cosmological era in 1997. We report on the final IPN localization of this event and its detailed multiwavelength study with a number of space-based instruments. The prompt emission is characterized by a typical duration, a moderare $E_{peak}$ of the time-integrated spectrum, and strong hard-to-soft evolution. The high observed energy fluence yields, at z=0.984, a huge isotropic-equivalent energy release $E_{iso}=(2.1\pm0.1)\times10^{54}$ erg. The record-breaking energy flux observed at the peak of the short, bright, hard initial pulse results in an unprecedented isotropic-equivalent luminosity $L_{iso}=(4.7\pm0.2)\times10^{54}$erg s$^{-1}$. A tail of the soft gamma-ray emission was detected with temporal and spectral behavior typical of that predicted by the synchrotron forward-shock model. Swift/XRT and Swift/UVOT observed the bright afterglow from 1.2 to 48 days after the burst and revealed no evidence of a jet break. The post-break scenario for the afterglow is preferred from our analysis, with a hard underlying electron spectrum and ISM-like circumburst environment implied. We conclude that, among multiple reasons investigated, the tight collimation of the jet must have been a key ingredient to produce this unusually bright burst. The inferred jet opening angle of 1.7-3.4 deg results in reasonable values of the collimation-corrected radiated energy and the peak luminosity, which, however, are still at the top of their distributions for such tightly collimated events. We estimate a detection horizon for a similar ultraluminous GRB of $z\sim7.5$ for Konus-WIND, and $z\sim12$ for Swift/BAT, which stresses the importance of GRBs as probes of the early Universe.Comment: 22 pages, 20 figures, accepted for publication in Ap

An exceptionally bright flare from SGR1806-20 and the origins of short-duration gamma-ray bursts

Soft-gamma-ray repeaters (SGRs) are galactic X-ray stars that emit numerous short-duration (about 0.1 s) bursts of hard X-rays during sporadic active periods. They are thought to be magnetars: strongly magnetized neutron stars with emissions powered by the dissipation of magnetic energy. Here we report the detection of a long (380 s) giant flare from SGR 1806-20, which was much more luminous than any previous transient event observed in our Galaxy. (In the first 0.2 s, the flare released as much energy as the Sun radiates in a quarter of a million years.) Its power can be explained by a catastrophic instability involving global crust failure and magnetic reconnection on a magnetar, with possible large-scale untwisting of magnetic field lines outside the star. From a great distance this event would appear to be a short-duration, hard-spectrum cosmic gamma-ray burst. At least a significant fraction of the mysterious short-duration gamma-ray bursts therefore may come from extragalactic magnetars.Comment: 21 pages, 5 figures. Published in Natur