Search results for "partitioning"
showing 10 items of 75 documents
Space-Frequency Quantization using Directionlets
2007
In our previous work we proposed a construction of critically sampled perfect reconstruction transforms with directional vanishing moments (DVMs) imposed in the corresponding basis functions along different directions, called directionlets. Here, we combine the directionlets with the space-frequency quantization (SFQ) image compression method, originally based on the standard two-dimensional (2-D) wavelet transform (WT). We show that our new compression method outperforms the standard SFQ as well as the state-of-the-art compression methods, like SPIHT and JPEG-2000, in terms of the quality of compressed images, especially in a low-rate compression regime. We also show that the order of comp…
A Predictive Approach for the Efficient Distribution of Agent-Based Systems on a Hybrid-Cloud
2018
International audience; Hybrid clouds are increasingly used to outsource non-critical applications to public clouds. However, the main challenge within such environments, is to ensure a cost-efficient distribution of the systems between the resources that are on/off premises. For Multi Agent Systems (MAS), this challenge is deepened due to irregular workload progress and intensive communication between the agents, which may result in high computing and data transfer costs. Thus, in this paper we propose a generic framework for adaptive cost-efficient deployment of MAS with a special focus on hybrid clouds. The framework is based mainly on the use of a performance evaluation process that con…
Exploring NoC Virtualization Alternatives in CMPs
2012
Chip Multiprocessor systems (CMPs) contain more and more cores in every new generation. However, applications for these systems do not scale at the same pace. Thus, in order to obtain a good utilization several applications will need to coexist in the system and in those cases virtualization of the CMP system will become mandatory. In this paper we analyze two virtualization strategies at NoC-level aiming to isolate the traffic generated by each application to reduce or even eliminate interferences among messages belonging to different applications. The first model handles most interferences among messages with a virtual-channels (VCs) implementation minimizing both execution time and netwo…
Ozone-induced reductions in below-ground biomass: an anatomical approach in potato
2010
[EN] Potato plants were grown in open-top chambers under three ozone concentrations during two complete cropping seasons (93 and 77 d in 2004 and 2005, respectively). The effects of chronic exposure to ozone on leaf anatomy, cell ultrastructure and crop yield were studied. Severe cell damage was found, even at ambient ozone levels, mainly affecting the spongy parenchyma and areas near the stomata. Damage to the cell wall caused loss of cell contact, and loss of turgor pressure due to tonoplast disintegration, contributed to cell collapse. Phloem sieve plates were obstructed by callose accumulation, and damaged mesophyll cells increased their starch stores. Tuber yield fell sharply (24–44%),…
Data Compression Using Wavelet and Local Cosine Transforms
2015
The chapter describes an algorithm that compresses two-dimensional data arrays, which are piece-wise smooth in one direction and have oscillating events in the other direction. Seismic, hyper-spectral and fingerprints data, for example, have such a mixed structure. The transform part of the compression process is an algorithm that combines wavelet and local cosine transform (LCT). The quantization and the entropy coding parts of the compression are taken from the SPIHT codec. To efficiently apply the SPIHT codec to a mixed coefficients array, reordering of the LCT coefficients takes place. On the data arrays, which have the mixed structure, this algorithm outperforms other algorithms that a…
Biotrickling filter modeling for styrene abatement. Part 2: Simulating a two-phase partitioning bioreactor.
2017
Abstract A dynamic model describing styrene abatement was developed for a two-phase partitioning bioreactor operated as a biotrickling filter (TPPB-BTF). The model was built as a coupled set of two different systems of partial differential equations depending on whether an irrigation or a non-irrigation period was simulated. The maximum growth rate was previously calibrated from a conventional BTF treating styrene (Part 1). The model was extended to simulate the TPPB-BTF based on the hypothesis that the main change associated with the non-aqueous phase is the modification of the pollutant properties in the liquid phase. The three phases considered were gas, a water–silicone liquid mixture, …
Trace metals supplementation in anaerobic membrane bioreactors treating highly saline phenolic wastewater
2017
Biomass requires trace metals (TM) for maintaining its growth and activity. This study aimed to determine the effect of TM supplementation and partitioning on the specific methanogenic activity (SMA), with a focus on cobalt and tungsten, during the start-up of two lab-scale Anaerobic Membrane Bioreactors (AnMBRs) treating saline phenolic wastewater. The TM partitioning revealed a strong accumulation of sodium in the biomass matrix and a wash-out of the majority of TM in the reactors, which led to an SMA decrease and a low COD removal of about 30%. The SMA exhibits a maximum at about 6 g Na+ L−1 and nearly complete inhibition at 34 g Na+ L−1. The dose of 0.5 mg L−1 of tungsten increases the …
A mixed geometric-systolic approach to parallel molecular dynamics simulations
1995
We have developed a flexible and efficient method of performing molecular dynamics simulations on distributed memory parallel computers. The novel feature is to use simultaneously spatial partitioning and systolic loop approaches according to a strategy which, for a given simulation, adapts itself to the multiprocessor system, allowing to approach optimal performance. The method assures high efficiencies even in situations in which, due to the exceeding large number of processors, the usage of a pure spatial decomposition would be impossible. The algorithm provides as particular cases both the pure spatial partitioning and the pure systolic parallelization schemes, so that its adoption assu…
On achieving intelligent traffic-aware consolidation of virtual machines in a data center using Learning Automata
2018
Unlike the computational mechanisms of the past many decades, that involved individual (extremely powerful) computers or clusters of machines, cloud computing (CC) is becoming increasingly pertinent and popular. Computing resources such as CPU and storage are becoming cheaper, and the servers themselves are becoming more powerful. This enables clouds to host more virtual machines (VMs). A natural consequence ofthis is that many modern-day data centers experience very high internaltraffic within the data centers themselves. This is, of course, due to the occurrence of servers that belong to the same tenant, communicating between themselves. The problem is accentuated when the VM deployment t…
Achieving Intelligent Traffic-aware Consolidation of Virtual Machines in a Data Center Using Learning Automata
2016
Cloud Computing (CC) is becoming increasingly pertinent and popular. A natural consequence of this is that many modern-day data centers experience very high internal traffic within the data centers themselves. The VMs with high mutual traffic often end up being far apart in the data center network, forcing them to communicate over unnecessarily long distances. The consequent traffic bottlenecks negatively affect both the performance of the application and the network in its entirety, posing nontrivial challenges for the administrators of these cloudbased data centers. The problem can, quite naturally, be compartmentalized into two phases which follow each other. First of all, the VMs are co…