High-Throughput Computing on High-Performance Platforms: A Case Study

The computing systems used by LHC experiments has historically consisted of the federation of hundreds to thousands of distributed resources, ranging from small to mid-size resource. In spite of the impressive scale of the existing distributed computing solutions, the federation of small to mid-size resources will be insufficient to meet projected future demands. This paper is a case study of how the ATLAS experiment has embraced Titan---a DOE leadership facility in conjunction with traditional distributed high- throughput computing to reach sustained production scales of approximately 52M core-hours a years. The three main contributions of this paper are: (i) a critical evaluation of design and operational considerations to support the sustained, scalable and production usage of Titan; (ii) a preliminary characterization of a next generation executor for PanDA to support new workloads and advanced execution modes; and (iii) early lessons for how current and future experimental and observational systems can be integrated with production supercomputers and other platforms in a general and extensible manner

PanDA Workload Management System Meta-data Segmentation

AbstractThe PanDA (Production and Distributed Analysis) workload management system (WMS) was developed to meet the scale and complexity of LHC distributed computing for the ATLAS experiment. PanDA currently distributes jobs among more than 100,000 cores at well over 120 Grid sites, supercomputing centers, commercial and academic clouds. ATLAS physicists submit more than 1.5M data processing, simulation and analysis PanDA jobs per day, and the system keeps all meta-information about job submissions and execution events in Oracle RDBMS. The above information is used for monitoring and accounting purposes. One of the most challenging monitoring issues is tracking errors that has occurred during the execution of the jobs. Current meta-data storage technology doesn’t support inner tools for data aggregation, needed to build error summary tables, charts and graphs. Delegating these tasks to the monitor slows down the execution of requests.We will describe a project aimed at optimizing interaction between PanDA front-end and back-end, by meta-data storage segmentation into two parts – operational and archived. Active meta-data are remained in Oracle database (operational part), due to the high requirements for data integrity. Historical (read-only) meta-data used for the system analysis and accounting are exported to NoSQL storage (archived part). New data model based on usage of Cassandra as the NoSQL backend has been designed as a set of query-specific data structures. This allowed to remove most of data preparation workload from PanDA Monitor and improve its scalability and performance. Segmentation and synchronization between operational and archived parts of jobs meta-data is provided by a Hybrid Meta-data Storage Framework (HMSF). PanDA monitor was partly adopted to interact with HMSF. The operational data queries are forwarded to the primary SQL-based repository and the analytic data requests are processed by NoSQL database. The results of performance and scalability tests of HMSF-adopted part of PanDA Monitor shows that presented method of optimization, in conjunction with a properly configured NoSQL database and reasonable data model, provides performance improvements and scalability

Preparation of Silcon Nanoparticles and Films By Pulsed Laser Deposition

Silicon films and nanoparticles were prepared by pulsed laser deposition under irradiation of crystalline silicon targets in residual inert gas atmosphere. Properties the prepared samples were investigated by means of the scanning probe microscopy. Keywords: pulsed laser deposition, scanning probe microscopy, silicon film, nanoparticles

Plasmon channels in the electronic relaxation of diamond under high-order harmonics femtosecond irradiation

We used high order harmonics of a femtosecond titanium-doped sapphire system (pulse duration 25 fs) to realise Ultraviolet Photoelectron Spectroscopy (UPS) measurements on diamond. The UPS spectra were measured for harmonics in the range 13 to 27. We also made ab initio calculations of the electronic lifetime of conduction electrons in the energy range produced in the UPS experiment. Such calculations show that the lifetime suddenly diminishes when the conduction electron energy reaches the plasmon energy, whereas the UPS spectra show evidence in this range of a strong relaxation mechanism with an increased production of low energy secondary electrons. We propose that in this case the electronic relaxation proceeds in two steps : excitation of a plasmon by the high energy electron, the latter decaying into individual electron-hole pairs, as in the case of metals. This process is observed for the first time in an insulator and, on account of its high efficiency, should be introduced in the models of laser breakdown under high intensity

Multi-kilowatt peak power nanosecond Er-doped fiber laser

We report a two-stage diode-pumped Er-doped fiber amplifier operating at the wavelength of 1550 nm at the repetition rate of 10-100 kHz with an average output power of up to 10 W. The first stage comprising Er-doped fiber was core-pumped at the wavelength of 1480 nm, whereas the second stage comprising double-clad Er/Yb-doped fiber was clad-pumped at the wavelength of 975 nm. The estimated peak power for the 0.4-nm full-width at half-maximum laser emission at the wavelength of 1550 nm exceeded 4-kW level. The initial 100-ns seed diode laser pulse was compressed to 3.5 ns as a result of the 34-dB total amplification. The observed 30-fold efficient pulse compression reveals a promising new nonlinear optical technique for the generation of high power short pulses for applications in eye-safe ranging and micromachining

The Tajik Civil War and Russia’s Islamist moment

Published online: 10 November 2022Contra the often-held assumption that the Islamist danger has been at the forefront of Moscow’s security agenda since the Soviet–Afghan War, this article shows how different Russian decision-makers held different views of Islamism during the Tajik Civil War (1992–97). It argues that different relations to the Soviet past, especially to the Soviet–Afghan War, explain the differences in assessing Islamism in Tajikistan between the security agencies and political elites. Unlike the reformers in the Kremlin, the legacy Soviet security elites and diplomats in Russia and the neo-communist leaders in Central Asia recalled the Islamist danger from Soviet times. They emphasized it to the Kremlin who came to embrace their view as the Tajik Civil War progressed and tensions rose in Chechnya

In search of Islamic legitimacy : the USSR, the Afghan communists and the Muslim world

Published online: 02 October 2022During the Afghan War, the Mujahideen claimed that the Afghan communists were atheists who were subservient to Moscow and did not have the legitimacy to rule Afghanistan. The war became a contest for legitimacy in Afghanistan and internationally. The Soviets and the Afghan communists portrayed communist Afghanistan as Islamic and therefore legitimate in the international arena. The Soviets elaborated an information campaign emphasising Islam and strengthened Afghanistan’s contacts with Muslim countries to show that the Afghan communists were Muslims too. They hoped international recognition would reduce Muslim countries’ support to the Mujahideen and improve the Afghan communists’ acceptance at home

Broadband dispersion measurement of ZBLAN, germanate and silica fibers in MidIR

We report the first ultra-broad band dispersion measurements in short-length ZBLAN, germanate and silica-based optical fibers in the near- and midIR wavelength ranges between 1.7 and 2.0 μ m and from 2.3 to 2.45 μm, using two ultra-broadband light sources: a broadband superluminescent Tm-doped fiber source and a novel femtosecond pulsed mode-locked Cr:ZnS oscillator. The measured second order dispersion characteristics of the fibers correspond to the theoretical predictions (numerical calculations)

“Communist Muslims” : The USSR and the people's democratic party of Afghanistan's conversion to Islam, 1978–1988

Soviet leaders sent troops into Afghanistan in December 1979 to support a friendly Marxist-Leninist regime in its conflict against a popular insurgency and help it build a new society. When the Soviet troops withdrew nine years later, they left behind a state that had none of the nominal characteristics of a Soviet-type Communist country. During the war, the People's Democratic Party of Afghanistan had discarded Marxism-Leninism and turned to Islam. This article examines how, with Moscow's support, the Afghan Communists Islamicized their discourse and policies as they tried to gain support from the population and co-opt insurgent fighters

Bringing the war home : the strategic logic of ‘North Caucasian terrorism’ in Russia

Published online: 03 July 2020Terrorism connected to the North Caucasus has been pervasive in Russia between 1992 and 2018. Based on an original dataset, this article presents statistics on rates of terrorist attacks outside of the North Caucasus, their geography and targets, and the tactics used. It argues that terrorism by North Caucasian insurgents has long retained a strategic logic despite their conversion to radical Islamism. Accordingly, the end of North Caucasian terrorism was determined by the erosion of its strategic character as an increasingly vague ideological project replaced concrete political goals among the insurgents