Non-catalytic bromination of benzene: a combined computational and experimental study

The non-catalytic bromination of benzene is shown experimentally to require high 5-14M concentrations of bromine in order to proceed at ambient temperatures to form predominantly bromobenzene, along with detectable (The non-catalytic bromination of benzene is shown experimentally to require high 5-14M concentrations of bromine in order to proceed at ambient temperatures to form predominantly bromobenzene, along with detectable (The non-catalytic bromination of benzene is shown experimentally to require high 5-14M concentrations of bromine in order to proceed at ambient temperatures to form predominantly bromobenzene, along with detectable

Исследование работы стеклопластиковых крепежных элементов в стеновых конструкциях

The article is devoted to the study of pull-out tests of fiberglass plastic dowels installed in the walls made of lightweight concrete. The authors have undertaken experimental tests of anchors in use on the construction site and conducted analysis of test results.Работа посвящена исследованию характеристик сцепления композитных стеклопластиковых дюбелей с легким бетоном. Авторами проведены экспериментальные испытания анкеров в натурных условияx на строительной площадке и выполнен анализ результатов испытаний

Mining open datasets for transparency in taxi transport in metropolitan environments.

Uber has recently been introducing novel practices in urban taxi transport. Journey prices can change dynamically in almost real time and also vary geographically from one area to another in a city, a strategy known as surge pricing. In this paper, we explore the power of the new generation of open datasets towards understanding the impact of the new disruption technologies that emerge in the area of public transport. With our primary goal being a more transparent economic landscape for urban commuters, we provide a direct price comparison between Uber and the Yellow Cab company in New York. We discover that Uber, despite its lower standard pricing rates, effectively charges higher fares on average, especially during short in length, but frequent in occurrence, taxi journeys. Building on this insight, we develop a smartphone application, OpenStreetCab, that offers a personalized consultation to mobile users on which taxi provider is cheaper for their journey. Almost five months after its launch, the app has attracted more than three thousand users in a single city. Their journey queries have provided additional insights on the potential savings similar technologies can have for urban commuters, with a highlight being that on average, a user in New York saves 6 U.S. Dollars per taxi journey if they pick the cheapest taxi provider. We run extensive experiments to show how Uber's surge pricing is the driving factor of higher journey prices and therefore higher potential savings for our application's users. Finally, motivated by the observation that Uber's surge pricing is occurring more frequently that intuitively expected, we formulate a prediction task where the aim becomes to predict a geographic area's tendency to surge. Using exogenous to Uber data, in particular Yellow Cab and Foursquare data, we show how it is possible to estimate customer demand within an area, and by extension surge pricing, with high accuracy.This is the final version of the article. It was first available from Springer via http://dx.doi.org/10.1140/epjds/s13688-015-0060-

The BaBar Event Building and Level-3 Trigger Farm Upgrade

The BaBar experiment is the particle detector at the PEP-II B-factory facility at the Stanford Linear Accelerator Center. During the summer shutdown 2002 the BaBar Event Building and Level-3 trigger farm were upgraded from 60 Sun Ultra-5 machines and 100MBit/s Ethernet to 50 Dual-CPU 1.4GHz Pentium-III systems with Gigabit Ethernet. Combined with an upgrade to Gigabit Ethernet on the source side and a major feature extraction software speedup, this pushes the performance of the BaBar event builder and L3 filter to 5.5kHz at current background levels, almost three times the original design rate of 2kHz. For our specific application the new farm provides 8.5 times the CPU power of the old system.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics (CHEP03), La Jolla, Ca, USA, March 2003, 4 pages, 1 eps figure, PSN MOGT00

Harmonic oscillators in the Nos\'e - Hoover thermostat

We study the dynamics of an ensemble of non-interacting harmonic oscillators in a nonlinear dissipative environment described by the Nos\'e - Hoover model. Using numerical simulation we find the histogram for total energy, which agrees with the analysis of the Nos\'e - Hoover equations effected with the method of averaging. The histogram does not correspond to Gibbs' canonical distribution. We have found oscillations at frequency proportional to $\sqrt{\alpha/m}$, $\alpha$ the dissipative parameter of thermostat and $m$ the characteristic mass of particle, about the stationary state corresponding to equilibrium. The oscillations could have an important bearing upon the analysis of simulating molecular dynamics in the Nos\'e - Hoover thermostat.Comment: 7 pages, 4 figure

2d Gauge Theories and Generalized Geometry

We show that in the context of two-dimensional sigma models minimal coupling of an ordinary rigid symmetry Lie algebra $\mathfrak{g}$ leads naturally to the appearance of the "generalized tangent bundle" $\mathbb{T}M \equiv TM \oplus T^*M$ by means of composite fields. Gauge transformations of the composite fields follow the Courant bracket, closing upon the choice of a Dirac structure $D \subset \mathbb{T}M$ (or, more generally, the choide of a "small Dirac-Rinehart sheaf" $\cal{D}$), in which the fields as well as the symmetry parameters are to take values. In these new variables, the gauge theory takes the form of a (non-topological) Dirac sigma model, which is applicable in a more general context and proves to be universal in two space-time dimensions: A gauging of $\mathfrak{g}$ of a standard sigma model with Wess-Zumino term exists, \emph{iff} there is a prolongation of the rigid symmetry to a Lie algebroid morphism from the action Lie algebroid $M \times \mathfrak{g}\to M$ into $D\to M$ (or the algebraic analogue of the morphism in the case of $\cal{D}$). The gauged sigma model results from a pullback by this morphism from the Dirac sigma model, which proves to be universal in two-spacetime dimensions in this sense.Comment: 22 pages, 2 figures; To appear in Journal of High Energy Physic

Virtual organizations internal structure projection methods for grid-infrastructures

Проведено аналіз особливостей внутрішньої структури віртуальних організацій (ВО) та показано їх вплив на ефективне планування ресурсів провайдером грід-інфраструктури. Досліджено методи виділення ресурсів Nordugrid ARC та сформовано методики розмежування доступу за параметрами участі у ВО. Відповідно до методик розроблено програмне забезпечення, яке успішно впроваджено на трьох кластерах українського національного грід (УНГ).Virtual Organizations (VOs) have an internal structure that was not driven by grid-infrastructure. The structure of the VO is influenced by many factors including number of members, resource usage, grid services usage and moreover social cooperation of researchers. Similarly to ordinary organizations that are usually divided into departments, hierarchical structure is also defined for the VOs. Generally, three parameters are used to describe VO structure: groups, roles and attributes. Grid-infrastructure resource provider's scheduler efficiency relies on VO internal structure recognition. Internal structure development process starts with VO particularity analysis. Virtual laboratory MolDynGrid that was established to conduct researches in structural biology and bioinformatics has been chosen as an example to demonstrate such analysis. Different requirements for several laboratory researches (molecular dynamics simulations using GROMACS software, molecular structure modeling using Modeller software, docking using AutoDock software) were described. Production versus testing computation properties were discussed. Based on performed analysis an internal structure for MolDynGrid VO has been settled. Methods of resource allocation employed by Nordugrid ARC were investigated. Necessity of binding different tasks to distinct queues of local resource management system has been shown. Lack of mechanisms for VO internal structure mapping to scheduler queues was pointed out. Analysis of the job processing algorithm in Nordugrid ARC computing element (A-REX) has shown that per-queue access control based on VO internal structure defined via Virtual Organization Membership Service (VOMS) attributes can be implemented as plug-in called out of A-REX when job gets moved to ACCEPTED state. Access separation algorithm has been developed and implemented in software. Plug-in introduces additional configuration options in Nordugrid ARC common configuration file that allow to specify access policy in terms of Fully Qualified Attribute Names (FQAN) representing internal structure developed for a VO. Software implementation of the methods presented has been successfully deployed on three Ukrainian National Grid clusters: Institute of Molecular Biology and Genetics NAS of Ukraine, Taras Shevchenko National University of Kyiv, National Scientific Centre for Medical and Biotechnical Research at the Presidium of NAS of Ukraine. Example of plug-in configuration considering particularities of Institute of Molecular Biology and Genetics NAS of Ukraine cluster has been shown. Methods are applicable to the other grid-enabled clusters