98,293 research outputs found
Theano: new features and speed improvements
Theano is a linear algebra compiler that optimizes a user's
symbolically-specified mathematical computations to produce efficient low-level
implementations. In this paper, we present new features and efficiency
improvements to Theano, and benchmarks demonstrating Theano's performance
relative to Torch7, a recently introduced machine learning library, and to
RNNLM, a C++ library targeted at recurrent neural networks.Comment: Presented at the Deep Learning Workshop, NIPS 201
A Domain-Specific Language and Editor for Parallel Particle Methods
Domain-specific languages (DSLs) are of increasing importance in scientific
high-performance computing to reduce development costs, raise the level of
abstraction and, thus, ease scientific programming. However, designing and
implementing DSLs is not an easy task, as it requires knowledge of the
application domain and experience in language engineering and compilers.
Consequently, many DSLs follow a weak approach using macros or text generators,
which lack many of the features that make a DSL a comfortable for programmers.
Some of these features---e.g., syntax highlighting, type inference, error
reporting, and code completion---are easily provided by language workbenches,
which combine language engineering techniques and tools in a common ecosystem.
In this paper, we present the Parallel Particle-Mesh Environment (PPME), a DSL
and development environment for numerical simulations based on particle methods
and hybrid particle-mesh methods. PPME uses the meta programming system (MPS),
a projectional language workbench. PPME is the successor of the Parallel
Particle-Mesh Language (PPML), a Fortran-based DSL that used conventional
implementation strategies. We analyze and compare both languages and
demonstrate how the programmer's experience can be improved using static
analyses and projectional editing. Furthermore, we present an explicit domain
model for particle abstractions and the first formal type system for particle
methods.Comment: Submitted to ACM Transactions on Mathematical Software on Dec. 25,
201
Dynamic Control Flow in Large-Scale Machine Learning
Many recent machine learning models rely on fine-grained dynamic control flow
for training and inference. In particular, models based on recurrent neural
networks and on reinforcement learning depend on recurrence relations,
data-dependent conditional execution, and other features that call for dynamic
control flow. These applications benefit from the ability to make rapid
control-flow decisions across a set of computing devices in a distributed
system. For performance, scalability, and expressiveness, a machine learning
system must support dynamic control flow in distributed and heterogeneous
environments.
This paper presents a programming model for distributed machine learning that
supports dynamic control flow. We describe the design of the programming model,
and its implementation in TensorFlow, a distributed machine learning system.
Our approach extends the use of dataflow graphs to represent machine learning
models, offering several distinctive features. First, the branches of
conditionals and bodies of loops can be partitioned across many machines to run
on a set of heterogeneous devices, including CPUs, GPUs, and custom ASICs.
Second, programs written in our model support automatic differentiation and
distributed gradient computations, which are necessary for training machine
learning models that use control flow. Third, our choice of non-strict
semantics enables multiple loop iterations to execute in parallel across
machines, and to overlap compute and I/O operations.
We have done our work in the context of TensorFlow, and it has been used
extensively in research and production. We evaluate it using several real-world
applications, and demonstrate its performance and scalability.Comment: Appeared in EuroSys 2018. 14 pages, 16 figure
Derivation of Einstein Cartan theory from general relativity
This work derives the elements of classical Einstein Cartan theory (EC) from
classical general relativity (GR) in two ways. (I) Derive translational
holonomy and the spin torsion field equation of EC for one Kerr mass in GR.
(II) Derive the field equations of EC as the continuum limit of a sequence of
discrete distributions of Kerr masses in classical GR with no electric charge.
his derivation does not extend to the quantum domain because of inequality
constraints. The convergence computations employ epsilon delta arguments, and
are not as rigorous as weak convergence in Sobolev norm. Derivation of EC from
GR strengthens the case for new physics derived from EC, including modeling
exchange of intrinsic and orbital angular momentum, removing some gravitational
singularities from Big Bang and black hole models, introducing a spin contact
force that is a geometric candidate for the origin of cosmic inflation, and
providing a better classical limit for theories of quantum gravity.Comment: 47 pages, 1 table, 66 equations, 3 figures, 93 lines of computer
algebra, 33 references. This version improves organization and many sections.
It argues that deriving EC from GR greatly strengthens the case for new
physics that is derived from EC; the new physics is listed. Section 2 updates
the 1986 paper below. Petti RJ, 1986, Gen Rel Grav vol 18, 441-46
Stability and mode analysis of solar coronal loops using thermodynamic irreversible energy principles
We study the modes and stability of non - isothermal coronal loop models with
different intensity values of the equilibrium magnetic field. We use an energy
principle obtained via non - equilibrium thermodynamic arguments. The principle
is expressed in terms of Hermitian operators and allow to consider together the
coupled system of equations: the balance of energy equation and the equation of
motion. We determine modes characterized as long - wavelength disturbances that
are present in inhomogeneous media. This character of the system introduces
additional difficulties for the stability analysis because the inhomogeneous
nature of the medium determines the structure of the disturbance, which is no
longer sinusoidal. Moreover, another complication is that we obtain a
continuous spectrum of stable modes in addition to the discrete one. We obtain
a unique unstable mode with a characteristic time that is comparable with the
characteristic life-time observed for loops. The feasibility of wave-based and
flow-based models is examined.Comment: 29 pages 10 figure
Mathematical Modeling of the Mojave Solar Plants
Competitiveness of solar energy is one of current main research topics. Overall efficiency
of solar plants can be improved by using advanced control strategies. To design and tuning properly
advanced control strategies, a mathematical model of the plant is needed. The model has to fulfill
two important points: (1) It has to reproduce accurately the dynamics of the real system; and (2) since
the model is used to test advanced control strategies, its computational burden has to be as low as
possible. This trade-off is essential to optimize the tuning process of the controller and minimize the
commissioning time. In this paper, the modeling of the large-scale commercial solar trough plants
Mojave Beta and Mojave Alpha is presented. These two models were used to test advanced control
strategies to operate the plants.Comisión Europea OCONTSOLAR 78905
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