Search results for " computing"

A dynamic program analysis to find floating-point accuracy problems

2012

Programs using floating-point arithmetic are prone to accuracy problems caused by rounding and catastrophic cancellation. These phenomena provoke bugs that are notoriously hard to track down: the program does not necessarily crash and the results are not necessarily obviously wrong, but often subtly inaccurate. Further use of these values can lead to catastrophic errors.In this paper, we present a dynamic program analysis that supports the programmer in finding accuracy problems. Our analysis uses binary translation to perform every floating-point computation side by side in higher precision. Furthermore, we use a lightweight slicing approach to track the evolution of errors.We evaluate our…

LARGE-SCALE SIMULATIONS IN CONDENSED MATTER PHYSICS —THE NEED FOR A TERAFLOP COMPUTER

1992

The introduction of vector processors {“supercomputers” with a performance in the range of 109 floating point operations (1 GFLOP) per second} has had an enormous impact on computational condensed matter physics. The possibility of a substantially enhanced performance by massively parallel processors (“teraflop” machines with 1012 floating point operations per second) will allow satisfactory treatment of a large range of important scientific problems which have to a great extent thus far escaped numerical resolution. The present paper describes only a few examples (out of a long list of interesting research problems!) for which the availability of “teraflops” will allow spectacular progres…

Reverse and normal drag along a fault

2005

An analysis of the theoretical displacement field around a single dip-slip fault at depth reveals that normal and reverse fault drag develop by perturbation flow induced by fault slip. We analytically model the heterogeneous part of the instantaneous displacement field of an isolated two-dimensional mode II fault in an infinite, homogeneous elastic body in response to fault slip. Material on both sides of the fault is displaced and ‘opposing circulation cells’ arise on opposite sides of the fault, with displacement magnitudes increasing towards the center of the fault. Both normal and reverse drag can develop at the fault center depending on the angle between the markers and the fault; norm…

Asymptotic regime in N random interacting species

2005

The asymptotic regime of a complex ecosystem with \emph{N}random interacting species and in the presence of an external multiplicative noise is analyzed. We find the role of the external noise on the long time probability distribution of the i-th density species, the extinction of species and the local field acting on the i-th population. We analyze in detail the transient dynamics of this field and the cavity field, which is the field acting on the $i^{th}$ species when this is absent. We find that the presence or the absence of some population give different asymptotic distributions of these fields.

Activation radius of aerosol particles in cloud events - ground based and aircraft field measurements

1997

A pre-processing and network analysis of GPS tracking data

2020

Global Positioning System (GPS) devices afford the opportunity to collect accurate data on unit movements from temporal and spatial perspectives. With a special focus on GPS technology in travel surveys, this paper proposes: (1) two algorithms for the pre-processing of GPS data in order to deal with outlier identification and missing data imputation; (2) a clustering approach to recover the main points of interest from GPS trajectories; and (3) a weighted-directed network, which incorporates the most relevant characteristics of the GPS trajectories at an aggregate level. A simulation study shows the goodness-of-fit of the imputation data algorithm and the robustness of the clustering algori…

Accelerating bioinformatics applications via emerging parallel computing systems [Guest editorial]

2015

The papers in this issue focus on advanced parallel computing systems for bioinformatics applications. This papers provide a forum to publish recent advances in the improvement of handling bioinformatics problems on emerging parallel computing systems. These systems can be characterized by exploiting different types of parallelism, including fine-grained versus coarse-grained and thread-level parallelism versus datalevel parallelism versus request-level parallelism. Hence, parallel computing systems based on multi- and many-core CPUs, many-core GPUs, vector processors, or FPGAs offer the promise to massively accelerate many bioinformatics algorithms and applications, ranging from computeint…

Special Section on ITS Services to Smart City Context [Guest Editorial]

2018

The seven articles in this special section focus on new trends and developments in the intelligent transportation markets. Since the earliest of times, transportation has changed and revolutionized society and industry. Many of technology advances were focused on transportation and their means (road, rail, air, water, etc.) even, today there exist several areas of the knowledge that are focused on it. As time goes by, new terms have been established where technology is present as well, for instance, Intelligent Transportation Systems (ITS), Smart Cities, Smart Territory, Blockchain, Internet of Things, virtualization, Cloud computing, Intelligent Vehicles, embedded computing, Deep learning,…

A preliminary framework for differentiating the paradigms of human-technology interaction research

2010

The purpose of this paper is to clarify the differences between approaches in the research field of human-technology interaction. We are especially interested in individuating user psychology from the more traditional paradigms. Therefore, we suggest a preliminary theoretical framework of criteria for distinguishing and individuating the different interaction research paradigms. The framework consists of five dimensions in which the paradigms may vary from each other. In this paper, we also discuss how ubiquitous computing is related to some of the dimensions. In addition, we focus on defining the new elements user psychology can bring to the discussion and analysis of human-technology inte…

Use of parallel computing to improve the accuracy of calculated molecular properties

1998

Calculation of electron correlation energy in molecules is unavoidable in accurate studies of chemical reactivity. However, these calculations involve, a computational effort several, even in the simplest cases, orders of magnitude larger than the computer power nowadays available. In this work the possibility of parallelize the calculations of the electron correlation energy is studied. The formalism chosen is the dressing of matrices in both distributed and shared memory parallel systems MIMD. Algorithms developed on PVM are presented, and the results are evaluated on several platforms. These results show that the parallel techniques are useful in order to decrease very appreciably the ti…