Multiple Parallel Cores Research Articles

ProPane: image warping with fire

ABSTRACT In this paper, we introduce the software package propane, written for the r data analysis language. propane combines the full range of wcslib projections with the C++ image manipulation routines provided by the cimg library. propane offers routines for image warping and combining (including stacking), and various related tasks such as image alignment tweaking and pixel masking. It can stack an effectively unlimited number of target frames using multiple parallel cores, and offers threading for many lower level routines. It has been used for a number of current and upcoming large surveys, and we present a range of its capabilities and features. propane is already available under a permissive open-source LGPL-3 license at github.com/asgr/ProPane (DOI: 10.5281/zenodo.10057053).

DaC‐Join: A join operator for improving database performance on modern hardware

SummaryThe computer industry is moving toward the construction in large scale of chips with hundreds of cores to increase on‐chip parallelism. In parallel, computers with solid state memory, the so‐called solid state drive (SSD for short), providing petabytes of storage area, is emerging. Nonetheless, database systems (DBSs) were designed based upon two premises. The first is the usage of magnetic disks (HDDs). The second one is that distributed DBSs could scale beyond what a single‐node DBMS can support. However, the latter premise only holds for a small number of CPU cores per node and for a limited number of nodes. Thus, to fully exploit benefits of parallelism and high IOPS rates supported by many‐core machines with SSDs, database systems should be aware of upcoming CPU architecture and storage technology. In this paper, we present a new join algorithm, denoted DaC‐Join, whose key goal is to exploit on‐chip parallelism and high IOPS rates delivered by modern hardware. DaC‐Join is able to run on multiple cores in parallel, increasing this way intra‐operator parallelism. Furthermore, the proposed operator effectively decreases the activity of writing back join temporary results on SSDs, which minimizes the problem of write operation latency in SSDs. In order to validate the novel approach, simulations with a prototype have been conducted over TPC‐H benchmark database, scale factor 10. The achieved results evidence the suitability of DaC‐Join.

Elliptic curve cryptography on embedded multicore systems

The increasing use of network-connected embedded devices and online transactions creates a growing demand of network security for embedded systems. The security requirements, such as authentication, confidentiality and integrity, always make computationally intensive processes and can easily become the bottleneck of the related applications. In this paper we implement Elliptic Curve Cryptography (ECC) (Miller in Lecture Notes in Computer Science, vol. 218, pp. 417---426, 1985; Koblitz in Math. Comput. 48:203---209, 1987) on an embedded multicore system, and explore the task scheduling methods in different levels. First, we propose an instruction scheduling method that utilizes all the cores to perform one modular operation in parallel. Second, we perform multiple modular operations with multiple cores in parallel. The performance of those two implementations is compared and a scheduling method combining these two types of parallelism is proposed. We discuss the details of our proposed method by using an FPGA implementation of ECC over a prime field.

Diversion and Cleanup Studies of Viscoelastic Surfactant-Based Self-Diverting Acid

Summary A self-diverting-acid based on viscoelastic surfactant (SDVA) has been successfully used recently on numerous stimulation treatments of carbonate formations in various fields. The decrease of acid concentration during the spending process viscosifies the fluid through the transformation from spherical micelles to an entangled wormlike micellar structure while penetrating the carbonate rock. The highly viscous fluid acts as a temporary barrier and diverts the fluid into the remaining lower-permeability treating zones. After treatment, the SDVA barrier breaks when contacted either by formation hydrocarbons or pre- and postflush fluids. Quantifying diversion, fluid efficiency, and cleanup are important factors for successful candidate selection and job design. Laboratory tests defining these key factors are presented in this paper. This paper demonstrates the diverting ability of the acid as a function of permeability, characterized by introducing the concept of maximum pressure ratio (dPmax/dP0) supported by core-flow and acid conductivity tests using limestone and dolomite cores. Results demonstrate high dPmax/dP0 in high-permeability cores and low dPmax/dP0 in low-permeability cores. Retained permeability measurements are presented that assess the level of cleanup. Flow-initiation experiments of spent acid systems with gas and brine were performed to illustrate the cleanup behavior of SDVA in comparison to gelled acid systems under conditions encountered in gas and oil wells. The results indicate that SDVA systems clean up easily and that SDVA provides higher regained permeability than conventional gelled acid systems. Background The purpose of matrix stimulation in limestone and dolomite reservoirs is the formation of wormholes, which can bypass the damaged areas and increase the effective wellbore area. When acid enters the formation with the highest injectivity it creates highly conductive flow channels, called wormholes, by dissolving the carbonate-containing minerals. Consequently, the injectivity will be further increased. The other zones are left untreated by the acid. To overcome this problem, a diverting agent is used. Mechanical diverters such as ball sealers, degradable ball sealers, rock salt, and benzoic acid flakes are used alone or in conjunction with chemical diverters based on foams or polymeric gels (Williams et al. 1979; Economides and Nolte 1989). These materials can work effectively only in a narrow permeability contrast and may result in residual damage (Lynn and Nasr-El-Din 2001). These characteristics are highly undesirable, particularly in low-pressure gas wells, and in long vertical and horizontal sections. Polymer-based systems such as in-situ crosslinked gelled acids (XLGA) have been used in the field as self-diverting fluids. These systems rely on a pH-triggered increase of viscosity during the acid spending process. Essentially, the pH change activates a metallic reagent that crosslinks the polymer chains, and the resulting viscosity increase causes a higher flow resistance (Mukherjee and Gudney 1993; Saxon et al. 1997). Further increase of the pH deactivates the metallic crosslinker and breaks the fluid down to the original linear gel with dissociated polymer chains. However, because of the nature of the long polymer chains, potential damage of the formation may occur (Lynn and Nasr-El-Din 2001). Recently, a new polymer-free self-diverting acid system was developed with a fluid stability in temperatures greater than 300°F (Taylor et al. 2003; Chang et al. 2001). The fluid system has been applied successfully in both matrix (Al-Mutawa et al. 2001) and acid-fracturing (Al-Muhareb et al. 2003; Artola et al. 2004) treatments. It causes rapid viscosity development throughout the spending process. The reduction in acid concentration, together with the simultaneous release of ions in solution, promotes the transformation from spherical micelles into worm-like micelles, resulting in increased viscosity of the fluid. The highly viscous fluid subsequently diverts the remaining acid treatment fluid into zones of lower injectivity by reducing the acid loss into wormholes, resulting in an improved zonal coverage of the treatment interval. Diversion tests using multiple parallel cores with varying permeabilities showed effective stimulation in all cores (Taylor et al. 2003; Chang et al. 2001). This paper presents new data providing further insight into the understanding of the unique properties of this SDVA based on laboratory studies. Specifically described are the chemical and physical properties of the SDVA fluid, including cleanup efficiency that is relevant to low-pressure reservoirs.

Between‐core vector overlapping for efficient core testing of system‐on‐chip LSI circuits

AbstractIn this paper, the authors propose a method for efficient parallel core testing for manufacturing testing of system‐on‐chip LSIs that consist of multiple full‐scan cores; this method is called “between‐core vector overlapping.” To shorten the time needed to test the entire SoC LSI, this uses a single bit sequence for test data (overlapped vector) obtained by overlapping test vectors of multiple cores as much as possible; during testing, this is fed jointly to each core, so that multiple cores can be tested in parallel. A key benefit of this method is that it minimizes the number of external input pins needed for testing multiple cores in parallel. To further reduce test times, the authors also propose methods for shortening the overlapped vectors: invert overlapping and split overlapping. Tests show these methods to be effective. © 2006 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 89(12): 53–62, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.20322