Cray X1 Evaluation Status Report

On August 15, 2002 the Department of Energy (DOE) selected the Center for Computational Sciences (CCS) at Oak Ridge National Laboratory (ORNL) to deploy a new scalable vector supercomputer architecture for solving important scientific problems in climate, fusion, biology, nanoscale materials and astrophysics. ''This program is one of the first steps in an initiative designed to provide U.S. scientists with the computational power that is essential to 21st century scientific leadership,'' said Dr. Raymond L. Orbach, director of the department's Office of Science The Cray X1 is an attempt to incorporate the best aspects of previous Cray vector systems and massively-parallel-processing (MPP) systems into one design. Like the Cray T90, the X1 has high memory bandwidth, which is key to realizing a high percentage of theoretical peak performance. Like the Cray T3E, the X1 has a high-bandwidth, low-latency, scalable interconnect, and scalable system software. And, like the Cray SV1, the X1 leverages commodity off-the-shelf (CMOS) technology and incorporates non-traditional vector concepts, like vector caches and multi-streaming processors. In FY03, CCS procured a 256-processor Cray X1 to evaluate the processors, memory subsystem, scalability of the architecture, software environment and to predict the expected sustained performance on key DOE applications codes. The results of the micro-benchmarks and kernel benchmarks show the architecture of the Cray X1 to be exceptionally fast for most operations. The best results are shown on large problems, where it is not possible to fit the entire problem into the cache of the processors. These large problems are exactly the types of problems that are important for the DOE and ultra-scale simulation

Numerical methods for the unsteady incompressible Navier-Stokes equations and their application to the Direct Numerical Simulation of turbulent flows

Two new methods for the efficient parallel computation of the unsteady incompressible Navier-Stokes equations are presented. Such efficient methods are desired for large scale parallel computations of unsteady turbulent flows such as Direct Numerical Simulations (DNS). The performance of the new methods has a distinct advantage over the artificial compressibility method, in that the methods exhibit robust convergence for a variety of flow problems without extensive need for tuning computational parameters. These methods and others have been implemented in a computer program designed for massively parallel computer architectures, written by the author and used to obtain all results in this work. A DNS of a film-cooling jet is performed in order to evaluate the accuracy of the modeled expressions in the k-e turbulence model. Using the results of the DNS, the terms in the exact and modeled k-e equations are computed. These terms are examined to see where the models fail for these flows. DNS budgets for k and dissipation in a film cooling jet flow are presented to provide turbulence modelers with information as to where the models used to replace the exact k-e equations need improvement for this particular type of flow. A DNS of a pulsed jet is performed to analyze the effect of external pulsing on the flow structures and the resulting mixing of the jet with the crossflow. As the problem is inherently unsteady, the key to the successful prediction of such flows is the ability to resolve the dynamics of all important flow structures resulting from the interaction of the unsteady pulsed jet with the crossflow. In the present work massless particles are released into the flow at various locations. These particles are colored by their seed locations and residence time, greatly aiding the understanding of the dynamics of the flow. A new origin for the formation of the wake vortices has been discovered for both pulsed and unpulsed jets. Pulsing is shown to drastically change the jet spreading and penetration and to increase the mixing of the jet with the crossflow. A significant asymmetry affecting primarily the wake vortices has been found for certain cases

Sensorless Control of the Synchronous Reluctance Motor

This thesis presents sensorless closed-loop speed control for the synchronous reluc-tance motor. The sensorless control is based on torque vector control. This is believed to be the first implementation of torque vector control. It has been implemented using a high-speed digital signal processor DSP96002. A constant current-angle controller (with rotor position sensor) for the syn-chronous reluctance motor was also developed on the same system. This controller was used as a benchmark for the sensorless torque vector control. It was also used to verify simulations and constant current-angle strategies. This is believed to be the first implementation of a number of original control strategies for the synchronous reluctance motor. Experimental results for sensorless operation a 120W axially laminated synchronous reluctance motor are presented and compared with operation with a speed sensor and simulations. Under sensorless operation a (constant-torque) speed range of 400-1500rpm has been achieved. With constant-power flux-weakening operation to the top speed was extended from 1500rpm to 2750rpm. The drive can withstand a full-load step-change within this speed range without losing synchronism under sensorless control. All the necessary equations for the various aspects of the performance of torque vector control have been developed. The effects of flux-linkage offset errors on the speed estimator and torque estimator have been analysed. Transient errors in the speed estimator due to sudden load changes have also been analysed

LIPIcs, Volume 261, ICALP 2023, Complete Volume

LIPIcs, Volume 261, ICALP 2023, Complete Volum

Semantic discovery and reuse of business process patterns

Patterns currently play an important role in modern information systems (IS) development and their use has mainly been restricted to the design and implementation phases of the development lifecycle. Given the increasing significance of business modelling in IS development, patterns have the potential of providing a viable solution for promoting reusability of recurrent generalized models in the very early stages of development. As a statement of research-in-progress this paper focuses on business process patterns and proposes an initial methodological framework for the discovery and reuse of business process patterns within the IS development lifecycle. The framework borrows ideas from the domain engineering literature and proposes the use of semantics to drive both the discovery of patterns as well as their reuse

Entwicklung eines Data Warehouses zur Durchführung von Zitierungsanalysen

In vergangenen Publikationen wurden bereits verschiedene Zitierungsanalysen durchgeführt. Jedoch stets auf unterschiedlichen Datenquellen, was einen direkten Vergleich der jeweiligen Ergebnisse verhindert. Ziel dieser Arbeit soll es sein, eine Grundlage zur flexiblen Durchführung von Zitierungsanalysen zu schaffen. Durch die Entwicklung eines Data Warehouses sollen verschiedene Datenquellen integriert und konsolidiert werden, um eine Vielfalt von Analyseperspektiven und Berechnungsverfahren auf einem einheitlichen Datenbestand zu ermöglichen. Dabei wird insbesondere auf die Besonderheiten bei der Nutzung von Webdatenquellen, als wie verschiedene Methoden zur Datenbereinigung eingegangen

Advances in Public Transport Platform for the Development of Sustainability Cities

Modern societies demand high and varied mobility, which in turn requires a complex transport system adapted to social needs that guarantees the movement of people and goods in an economically efficient and safe way, but all are subject to a new environmental rationality and the new logic of the paradigm of sustainability. From this perspective, an efficient and flexible transport system that provides intelligent and sustainable mobility patterns is essential to our economy and our quality of life. The current transport system poses growing and significant challenges for the environment, human health, and sustainability, while current mobility schemes have focused much more on the private vehicle that has conditioned both the lifestyles of citizens and cities, as well as urban and territorial sustainability. Transport has a very considerable weight in the framework of sustainable development due to environmental pressures, associated social and economic effects, and interrelations with other sectors. The continuous growth that this sector has experienced over the last few years and its foreseeable increase, even considering the change in trends due to the current situation of generalized crisis, make the challenge of sustainable transport a strategic priority at local, national, European, and global levels. This Special Issue will pay attention to all those research approaches focused on the relationship between evolution in the area of transport with a high incidence in the environment from the perspective of efficiency

The Effect of Deep-Water Multibeam Mapping Activity on the Foraging Behavior of Cuvier’s Beaked Whales and the Marine Acoustic Environment

Sound can propagate great distances underwater and is an important mode for marine life to obtain information. Human activities in the ocean such as global shipping, coastal construction, gas and oil exploration, and mapping navigation routes intentionally and unintentionally emit sound into the ocean, potentially interacting with marine life. Therefore, it is essential that the effects of anthropogenic noise on marine life and the ambient marine acoustic environment be understood. Most of the work, to date, has focused on the impact of low-frequency (\u3c1 kHz) sources such as shipping noise, which is ubiquitous in the ocean, and mid-frequency (1-10 kHz) sources such as naval sonar, to which many marine mammals have shown to be sensitive. The effect of these sources can be as salient as a mass stranding event or as benign as an animal swimming away from a source of noise with no other effect. Less work has focused on higher frequency sources (\u3e10 kHz), including ocean-mapping sonar systems. However, most marine mammals, namely toothed whales (odontocetes), are capable of hearing mapping-sonar signals. The exposure of marine mammals to anthropogenic sound sources in the open ocean is regulated by the National Marine Fisheries Services through the Marine Mammal Protection Act (MMC 2015), the Endangered Species Act (DoI 2003), and the National Environmental Policy Act. Without a better understanding of the interaction of mapping sonar with marine mammals, the current guidelines imposed for marine mammal protection may not be protective enough, or alternatively, may be too conservative. To gain a better understanding of the potential effect of mapping sonar and marine mammals, a scenario was examined that is possible to occur and has a high potential for a biologically meaningful interaction between mapping sonar and a sensitive marine mammal species: a 12-kHz multibeam echosounder (MBES) mapping survey and beaked whale foraging. This represents a possible interaction since 1) the relatively low frequency of the 12 kHz MBES propagates further in the ocean environment than other mapping sonar frequencies (\u3e30 kHz), and 2) beaked whales commonly reside in the deep-water environments where mapping with such a system would occur. Due to 1) the overlap of the frequency of this mapping system with beaked whales hearing, and 2) the life-sustaining nature of the behavior under consideration, this interaction has the potential to be biologically meaningful. To understand the effect of deep-water multibeam mapping activity on beaked whale foraging, the temporal and spatial foraging behavior of beaked whales was assessed during two three-day ocean mapping surveys over the Southern California Antisubmarine Warfare Range hydrophone array (SOAR, featuring 89 bottom-mounted receivers over a 1800 km2 area) utilizing a 12-kHz deep-water multibeam echosounder. Echolocation clicks recorded on the hydrophone receivers from foraging Cuvier’s beaked whales were used as a proxy to assess their foraging behavior. In addition, a soundscape analysis was conducted using the acoustic data from the hydrophone array to provide context for the behavior study findings, as well as provide a more general perspective on the contribution of the deep-water mapping activity to the marine acoustic environment. In the first phase of this work, passive acoustic monitoring data was used to identify foraging events of beaked whales. Four characteristics of the foraging events were used as proxies for foraging behavior and were subsequently compared Before, During, and After two deep-water ocean mapping surveys. These included 1) the number of foraging events (Group Vocal Periods, or GVPs), 2) the number of clicks per GVP, 3) GVP duration and 4) click rate per GVP. The findings of this effort revealed that only the number of GVPs increased during the deep-water mapping surveys, largely driven by the observations in just one of the survey years. This temporal analysis showed no impact on beaked whale foraging except for an increase in foraging effort during mapping activity. In addition, this finding was a stark contrast to foraging behavior of beaked whales during MFAS activity, during which the number of foraging events decreased. In the second phase of this work, an approach --the Global-Local-Comparison Approach (GLC)--was developed and tested that uses existing disparate spatial statistics and statistical hypothesis testing to assess whether a change in spatial behavior has occurred. Using three-prongs of assessment—global, local, and comparison—the approach provided knowledge about 1) the general distribution of observations over the entire area of study (i.e., clustered, random, dispersed), 2) identification of local hot and cold spots of activity, and 3) order-of-magnitude differences across distinct analysis periods, respectively. The approach was demonstrated on synthetic data and empirical case studies of marine mammal behavior to determine its effectiveness and limitations in assessing change in spatial observations across analysis periods. The results revealed that the approach was effective at identifying visually identifiable spatial changes, with robust statistical support. The GLC Approach was then used to assess spatial change in beaked whale foraging behavior before, during, and after ocean mapping activity using the spatial data from the foraging events used in the first phase of work. The analysis revealed that for one of the years of study there was no obvious change in foraging behavior globally, locally, or in magnitude in response to the mapping activity, whereas a local change in beaked whale foraging effort was identified during the second mapping survey year. There were obvious differences in the spatial use of the array by foraging animals between the two years outside of the survey work, which in addition to the differences in results between the two years of study, provided little support that the local change identified was necessarily a response to the mapping activity. The final phase of research was to characterize the contribution of one of the two ocean mapping surveys to the marine soundscape utilizing the acoustic data from the SOAR array, with a particular emphasis on understanding the contribution of the 12 kHz deep-water MBES. A comprehensive, multi-analysis approach focused on amplitude and frequency features of the changing soundscape across a nine-hydrophone subset of the array and across four analysis periods with respect to the survey activity: No Activity, Vessel Only, Vessel and MBES, and Mixed Acoustics was conducted. The analyses revealed that the contribution of the deep-water MBES to the acoustic environment was very stereotyped: contributing most substantially to the loudest sound levels in the soundscape, particularly in the 12.5 kHz decidecade band. These results aligned well with the physical characteristics of the system, i.e., nominal frequency, duty-cycle, transmission geometry, etc., suggesting these parameters can be reliably used to identify this source in subsequent soundscape studies. The assessment revealed that the MBES was the most consistent loud source throughout the survey period, but was intermittently present. There were other loud acoustic sources detected throughout the survey period, most frequently other vessels and biological activity. Several of the metrics used were weighted based on the hearing sensitivity of a mid-frequency cetacean, chosen specifically to provide context for what a Cuvier’s beaked whale may have heard if in the area where the survey was conducted. The most important finding related to this aspect of the work was that the survey activity, particularly the MBES sound, did not contribute uniformly in space, time, or frequency to the SOAR soundscape of the mapping survey: it had a very local and transient effect. In summary, at the resolution of the SOAR hydrophone array, this empirical work assessing beaked whale foraging during deep-water MBES mapping activity demonstrated: 1) no adverse changes in Cuvier’s beaked whale foraging behavior, and 2) no clear response to the deep-water MBES mapping activity. Deep-water MBES mapping activity contributed substantially to the change in sound levels at a finite scale around the survey vessel. This led to a temporally intermittent impact on the soundscape at a given location. Within these spatio-temporal bounds, deep-water MBES mapping activity has the potential to be detected by a Cuvier’s beaked whale due to its spectral overlap with the frequencies of best hearing sensitivity of this species, as well as its loudness. However, no adverse effects on Cuvier’s beaked whale foraging were observed here