4,113 research outputs found
A Genetic Algorithm for Power-Aware Virtual Machine Allocation in Private Cloud
Energy efficiency has become an important measurement of scheduling algorithm
for private cloud. The challenge is trade-off between minimizing of energy
consumption and satisfying Quality of Service (QoS) (e.g. performance or
resource availability on time for reservation request). We consider resource
needs in context of a private cloud system to provide resources for
applications in teaching and researching. In which users request computing
resources for laboratory classes at start times and non-interrupted duration in
some hours in prior. Many previous works are based on migrating techniques to
move online virtual machines (VMs) from low utilization hosts and turn these
hosts off to reduce energy consumption. However, the techniques for migration
of VMs could not use in our case. In this paper, a genetic algorithm for
power-aware in scheduling of resource allocation (GAPA) has been proposed to
solve the static virtual machine allocation problem (SVMAP). Due to limited
resources (i.e. memory) for executing simulation, we created a workload that
contains a sample of one-day timetable of lab hours in our university. We
evaluate the GAPA and a baseline scheduling algorithm (BFD), which sorts list
of virtual machines in start time (i.e. earliest start time first) and using
best-fit decreasing (i.e. least increased power consumption) algorithm, for
solving the same SVMAP. As a result, the GAPA algorithm obtains total energy
consumption is lower than the baseline algorithm on simulated experimentation.Comment: 10 page
Digital Control and Monitoring Methods for Nonlinear Processes
The chemical engineering literature is dominated by physical and (bio)-chemical processes that exhibit complex nonlinear behavior, and as a consequence, the associated requirements of their analysis, optimization, control and monitoring pose considerable challenges in the face of emerging competitive pressures on the chemical, petrochemical and pharmaceutical industries. The above operational requirements are now increasingly imposed on processes that exhibit inherently nonlinear behavior over a wide range of operating conditions, rendering the employment of linear process control and monitoring methods rather inadequate. At the same time, increased research efforts are now concentrated on the development of new process control and supervisory systems that could be digitally implemented with the aid of powerful computer software codes. In particular, it is widely recognized that the important objective of process performance reliability can be met through a comprehensive framework for process control and monitoring. From:
(i) a process safety point of view, the more reliable the process control and monitoring scheme employed and the earlier the detection of an operationally hazardous problem, the greater the intervening power of the process engineering team to correct it and restore operational order
(ii) a product quality point of view, the earlier detection of an operational problem might prevent the unnecessary production of o-spec products, and subsequently minimize cost.
The present work proposes a new methodological perspective and a novel set of systematic analytical tools aiming at the synthesis and tuning of well-performing digital controllers and the development of monitoring algorithms for nonlinear processes. In particular, the main thematic and research axis traced are:
(i) The systematic integrated synthesis and tuning of advanced model-based digital controllers using techniques conceptually inspired by Zubov’s advanced stability theory.
(ii) The rigorous quantitative characterization and monitoring of the asymptotic behavior of complex nonlinear processes using the notion of invariant manifolds and functional equations theory.
(iii) The systematic design of nonlinear state observer-based process monitoring systems to accurately reconstruct unmeasurable process variables in the presence of time-scale multiplicity.
(iv) The design of robust nonlinear digital observers for chemical reaction systems in the presence of model uncertainty
A Dynamical Model of Twitter Activity Profiles
The advent of the era of Big Data has allowed many researchers to dig into
various socio-technical systems, including social media platforms. In
particular, these systems have provided them with certain verifiable means to
look into certain aspects of human behavior. In this work, we are specifically
interested in the behavior of individuals on social media platforms---how they
handle the information they get, and how they share it. We look into Twitter to
understand the dynamics behind the users' posting activities---tweets and
retweets---zooming in on topics that peaked in popularity. Three mechanisms are
considered: endogenous stimuli, exogenous stimuli, and a mechanism that
dictates the decay of interest of the population in a topic. We propose a model
involving two parameters and describing the tweeting
behaviour of users, which allow us to reconstruct the findings of Lehmann et
al. (2012) on the temporal profiles of popular Twitter hashtags. With this
model, we are able to accurately reproduce the temporal profile of user
engagements on Twitter. Furthermore, we introduce an alternative in classifying
the collective activities on the socio-technical system based on the model.Comment: 10 pages, 5 figure
Stable scalable control of soliton propagation in broadband nonlinear optical waveguides
We develop a method for achieving scalable transmission stabilization and
switching of colliding soliton sequences in optical waveguides with
broadband delayed Raman response and narrowband nonlinear gain-loss. We show
that dynamics of soliton amplitudes in -sequence transmission is described
by a generalized -dimensional predator-prey model. Stability and bifurcation
analysis for the predator-prey model are used to obtain simple conditions on
the physical parameters for robust transmission stabilization as well as on-off
and off-on switching of out of soliton sequences. Numerical simulations
for single-waveguide transmission with a system of coupled nonlinear
Schr\"odinger equations with show excellent agreement with the
predator-prey model's predictions and stable propagation over significantly
larger distances compared with other broadband nonlinear single-waveguide
systems. Moreover, stable on-off and off-on switching of multiple soliton
sequences and stable multiple transmission switching events are demonstrated by
the simulations. We discuss the reasons for the robustness and scalability of
transmission stabilization and switching in waveguides with broadband delayed
Raman response and narrowband nonlinear gain-loss, and explain their advantages
compared with other broadband nonlinear waveguides.Comment: 37 pages, 7 figures, Eur. Phys. J. D (accepted
Metric Regularity of the Sum of Multifunctions and Applications
In this work, we use the theory of error bounds to study metric regularity of
the sum of two multifunctions, as well as some important properties of
variational systems. We use an approach based on the metric regularity of
epigraphical multifunctions. Our results subsume some recent results by Durea
and Strugariu.Comment: Submitted to JOTA 37 page
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