540 research outputs found
Produção de biogás a partir do glicerol oriundo do biodiesel.
bitstream/item/55346/1/COT11018.pd
Autonomous Configuration of Network Parameters in Operating Systems using Evolutionary Algorithms
By default, the Linux network stack is not configured for highspeed large
file transfer. The reason behind this is to save memory resources. It is
possible to tune the Linux network stack by increasing the network buffers size
for high-speed networks that connect server systems in order to handle more
network packets. However, there are also several other TCP/IP parameters that
can be tuned in an Operating System (OS). In this paper, we leverage Genetic
Algorithms (GAs) to devise a system which learns from the history of the
network traffic and uses this knowledge to optimize the current performance by
adjusting the parameters. This can be done for a standard Linux kernel using
sysctl or /proc. For a Virtual Machine (VM), virtually any type of OS can be
installed and an image can swiftly be compiled and deployed. By being a
sandboxed environment, risky configurations can be tested without the danger of
harming the system. Different scenarios for network parameter configurations
are thoroughly tested, and an increase of up to 65% throughput speed is
achieved compared to the default Linux configuration.Comment: ACM RACS 201
Geração de metano a partir de resíduos lignocelulósicos oriundos da produção do biocombustível: revisão.
Ordered La0.7Sr0.3MnO3 nanohole arrays fabricated on a nanoporous alumina template by pulsed laser ablation
Highly ordered nanohole arrays of [Formula: see text] manganite have been synthesized using pulsed laser deposition on nanoporous alumina template. Their structure and phase formation were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive x-ray spectroscopy (EDX) and x-ray diffraction (XRD). The magnetic measurements were performed with respect to temperature and field and exhibit a ferromagnetic to paramagnetic transition at 284 K. In addition, the temperature dependence of electrical resistance was measured at different magnetic fields and an insulating phase throughout all the temperatures was observed. The low temperature ferromagnetic insulating state is discussed by the presence of a canted ferromagnetic state induced by the nanoholes. The present work shows the feasibility of combining both the nanoporous alumina template and pulsed laser ablation for the fabrication of perovskite manganite nanohole arrays which can also be extended to fabricate other multicomponent oxide nanohole materials.M K is thankful to FCT, Portugal for the Grant No. SFRH/ BPD/75110/2010. The authors acknowledged the financial supports from the projects NORTE-07–0124-FEDER000070, CERN/FIS-NUC/0004/2015 and IF/00686/2014
- …