31,400 research outputs found
Illumination system including a virtual light source Patent
Illumination system design for use as sunlight simulator in space environment simulators with multiple light sources reflected to single virtual sourc
Truthful Online Scheduling with Commitments
We study online mechanisms for preemptive scheduling with deadlines, with the
goal of maximizing the total value of completed jobs. This problem is
fundamental to deadline-aware cloud scheduling, but there are strong lower
bounds even for the algorithmic problem without incentive constraints. However,
these lower bounds can be circumvented under the natural assumption of deadline
slackness, i.e., that there is a guaranteed lower bound on the ratio
between a job's size and the time window in which it can be executed.
In this paper, we construct a truthful scheduling mechanism with a constant
competitive ratio, given slackness . Furthermore, we show that if is
large enough then we can construct a mechanism that also satisfies a commitment
property: it can be determined whether or not a job will finish, and the
requisite payment if so, well in advance of each job's deadline. This is
notable because, in practice, users with strict deadlines may find it
unacceptable to discover only very close to their deadline that their job has
been rejected
A Java based simulation for basic control
7th IFAC Symposium on Advances in Control Education 21/06/2006 MadridIn this paper we present a java based simulator for control education in basiccourses. The application has been developed using the well known tool Easy JavaSimulation.The objective of the application is to help the student to learn the design of classiccontrollers such as P,PI, PID, etc testing the tuning procedures to control the position ofan antenna controlled by a DC motor. Thus the application allows the student to choosethe parameters of the antenna and the DC motor, to choose the controller to be used andits parameters and finally to simulate the closed loop system observing the evolution ofthe signals as well as a 3-D view. Furthermore, in order to show the real behavior of thesystem, dead zone, saturation, disturbances and non-linearities can be added to the model.This application has been used by the authors to teach a basic control course at EscuelaSuperior de Ingenieros (University of Seville) as virtual laboratory.Moreover, since the application is java based, this can be used by the students from theauthors’ web pages and this can also be installed in the student’s laptop (whichever theplatform is) by downloading it from the authors web page (Limon and Salas, 2003Ministerio de Ciencia y TecnologÃa DPI2004-07444Ministerio de Ciencia y TecnologÃa DPI2003-0042
A First Step toward the Understanding of Implicit Learning of Hazard Anticipation in Inexperienced Road Users Through a Moped-Riding Simulator
Hazard perception is considered one of the most important abilities in road safety.
Several efforts have been devoted to investigating how it improves with experience
and can be trained. Recently, research has focused on the implicit aspects of hazard
detection, reaction, and anticipation. In the present study, we attempted to understand
how the ability to anticipate hazards develops during training with a moped-riding
simulator: the Honda Riding Trainer (HRT). Several studies have already validated the
HRT as a tool to enhance adolescents\u2019 hazard perception and riding abilities. In the
present study, as an index of hazard anticipation, we used skin conductance response
(SCR), which has been demonstrated to be linked to affective/implicit appraisal of risk.
We administered to a group of inexperienced road users five road courses two times a
week apart. In each course, participants had to deal with eight hazard scenes (except
one course that included only seven hazard scenes). Participants had to ride along
the HRT courses, facing the potentially hazardous situations, following traffic rules, and
trying to avoid accidents. During the task, we measured SCR and monitored driving
performance. The main results show that learning to ride the simulator leads to both a
reduction in the number of accidents and anticipation of the somatic response related
to hazard detection, as proven by the reduction of SCR onset recorded in the second
session. The finding that the SCR signaling the impending hazard appears earlier when
the already encountered hazard situations are faced anew suggests that training with
the simulator acts on the somatic activation associated with the experience of risky
situations, improving its effectiveness in detecting hazards in advance so as to avoid
accidents. This represents the starting point for future investigations into the process of
generalization of learning acquired in new virtual situations and in real-road situations
ERA: A Framework for Economic Resource Allocation for the Cloud
Cloud computing has reached significant maturity from a systems perspective,
but currently deployed solutions rely on rather basic economics mechanisms that
yield suboptimal allocation of the costly hardware resources. In this paper we
present Economic Resource Allocation (ERA), a complete framework for scheduling
and pricing cloud resources, aimed at increasing the efficiency of cloud
resources usage by allocating resources according to economic principles. The
ERA architecture carefully abstracts the underlying cloud infrastructure,
enabling the development of scheduling and pricing algorithms independently of
the concrete lower-level cloud infrastructure and independently of its
concerns. Specifically, ERA is designed as a flexible layer that can sit on top
of any cloud system and interfaces with both the cloud resource manager and
with the users who reserve resources to run their jobs. The jobs are scheduled
based on prices that are dynamically calculated according to the predicted
demand. Additionally, ERA provides a key internal API to pluggable algorithmic
modules that include scheduling, pricing and demand prediction. We provide a
proof-of-concept software and demonstrate the effectiveness of the architecture
by testing ERA over both public and private cloud systems -- Azure Batch of
Microsoft and Hadoop/YARN. A broader intent of our work is to foster
collaborations between economics and system communities. To that end, we have
developed a simulation platform via which economics and system experts can test
their algorithmic implementations
Design and Simulation of Wave Shaping Schemes for a Virtual Data Communication and Impaired Link Environment System for Advanced ICT Education
Design and Simulation of Waves
Shaping Schemes for a Virtual Data
Communication and Impaired Link
Environment System for Advanced ICT
Education is aimed at providing a simulator for
the performance of digital filtering of signals for
data communication experiments with the aid of
MATLAB. A fundamental aspect of signal
processing is filtering. Filtering involves the
manipulation of the spectrum of a signal by
passing or blocking certain portions of the
spectrum, depending on the frequency of those
portions. This work is designed to provide a
flexible platform for teaching the operations of
waves shaping schemes (lowpass, bandpass and
highpass) modelled over an additive white
Gaussian noise (AWGN) channel.
Keywords – Lowpass, Bandpass, Highpass,
MATLAB
A TCP/IP Network Emulator
In this paper a Linux based framework of a TCP/IP emulator is introduced. Several advantages can be noted. Firstly, the maintenance of large numbers of processors is unnecessary. Secondly, compared with simulators constructed with conceptual codes, our emulator framework makes it possible to test the interaction and behaviour of TCP/IP in real Linux network environments. Thirdly, the wired network is fully controlled by a single processor enabling us to separate TCP/IP behaviour over the wireless network, which helps distinguish performance functions that occur due to noisy wireless links. The framework was tested on two Linux processors over an IEEE802.11b wireless link. The simulations show that the complex topology of the heterogeneous network was "realistically" constructed
SpikingLab: modelling agents controlled by Spiking Neural Networks in Netlogo
The scientific interest attracted by Spiking Neural Networks (SNN) has lead to the development of tools for the simulation and study of neuronal dynamics ranging from phenomenological models to the more sophisticated and biologically accurate Hodgkin-and-Huxley-based and multi-compartmental models. However, despite the multiple features offered by neural modelling tools, their integration with environments for the simulation of robots and agents can be challenging and time consuming. The implementation of artificial neural circuits to control robots generally involves the following tasks: (1) understanding the simulation tools, (2) creating the neural circuit in the neural simulator, (3) linking the simulated neural circuit with the environment of the agent and (4) programming the appropriate interface in the robot or agent to use the neural controller. The accomplishment of the above-mentioned tasks can be challenging, especially for undergraduate students or novice researchers. This paper presents an alternative tool which facilitates the simulation of simple SNN circuits using the multi-agent simulation and the programming environment Netlogo (educational software that simplifies the study and experimentation of complex systems). The engine proposed and implemented in Netlogo for the simulation of a functional model of SNN is a simplification of integrate and fire (I&F) models. The characteristics of the engine (including neuronal dynamics, STDP learning and synaptic delay) are demonstrated through the implementation of an agent representing an artificial insect controlled by a simple neural circuit. The setup of the experiment and its outcomes are described in this work
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