8,529 research outputs found
A general approach to Bayesian portfolio optimization
We develop a general approach to portfolio optimization taking account of estimation risk and stylized facts of empirical finance. This is done within a Bayesian framework. The approximation of the posterior distribution of the unknown model parameters is based on a parallel tempering algorithm. The portfolio optimization is done using the first two moments of the predictive discrete asset return distribution. For illustration purposes we apply our method to empirical stock market data where daily asset logreturns are assumed to follow an orthogonal MGARCH process with t-distributed perturbations. Our results are compared with other portfolios suggested by popular optimization strategies. --Bayesian portfolio optimization,Gordin's condition,Markov chain Monte Carlo,Stylized facts
Reconstruction of Residual Stress in a Welded Plate Using the Variational Eigenstrain Approach
We present the formulation for finding the distribution of eigenstrains, i.e.
the sources of residual stress, from a set of measurements of residual elastic
strain (e.g. by diffraction), or residual stress, or stress redistribution, or
distortion. The variational formulation employed seeks to achieve the best
agreement between the model prediction and some measured parameters in the
sense of a minimum of a functional given by a sum over the entire set of
measurements. The advantage of this approach lies in its flexibility: different
sets of measurements and information about different components of the
stress-strain state can be incorporated. We demonstrate the power of the
technique by analysing experimental data for welds in thin sheet of a nickel
superalloy aerospace material. Very good agreement can be achieved between the
prediction and the measurement results without the necessity of using iterative
solution. In practice complete characterisation of residual stress states is
often very difficult, due to limitations of facility access, measurement time
or specimen dimensions. Implications of the new technique for experimental
analysis are all the more significant, since it allows the reconstruction of
the entire stress state from incomplete sets of data.Comment: 16 pages, 17 figure
Systematic study of infrared energy corrections in truncated oscillator spaces
We study the convergence properties of nuclear binding energies and
two-neutron separation energies obtained with self-consistent mean-field
calculations based on the Hartree-Fock-Bogolyubov (HFB) method with Gogny-type
effective interactions. Owing to lack of convergence in a truncated working
basis, we employ and benchmark one of the recently proposed infrared energy
correction techniques to extrapolate our results to the limit of an infinite
model space. We also discuss its applicability to global calculations of
nuclear masses.Comment: 12 pages, 12 figure
Restriction of odd degree characters and natural correspondences
Let be an odd prime power, , and let denote a maximal
parabolic subgroup of with Levi subgroup . We restrict the odd-degree irreducible characters of to
to discover a natural correspondence of characters, both for and
. A similar result is established for certain finite groups with
self-normalizing Sylow -subgroups. We also construct a canonical bijection
between the odd-degree irreducible characters of and those of , where
is any maximal subgroup of of odd index; as well as between the
odd-degree irreducible characters of or with odd
and those of , where is a Sylow -subgroup of . Since our
bijections commute with the action of the absolute Galois group over the
rationals, we conclude that the fields of values of character correspondents
are the same. We use this to answer some questions of R. Gow
Black Bottom
For this paper, I chose to examine the character of Beneatha Younger from A Raisin in the Sun, her relationships with other characters, and how it relates to Afrocentrism
Body randomization reduces the sim-to-real gap for compliant quadruped locomotion
Designing controllers for compliant, underactuated robots is challenging and usually requires a learning procedure. Learning robotic control in simulated environments can speed up the process whilst lowering risk of physical damage. Since perfect simulations are unfeasible, several techniques are used to improve transfer to the real world. Here, we investigate the impact of randomizing body parameters during learning of CPG controllers in simulation. The controllers are evaluated on our physical quadruped robot. We find that body randomization in simulation increases chances of finding gaits that function well on the real robot
Cognitive-linguistic manipulation and persuasion in Agatha Christie
This thesis presents some of the many methods which Agatha Christie uses to manipulate readers away from and towards the eventual resolutions of her fiction. It draws on a variety of linguistic, psychological, narratological and stylistic models to describe the specific techniques employed by Christie to manipulate and distract her readers.
The research undertaken employs practical studies in schemata, scenario-dependence, depth of cognitive processing, rhetorical-structural persuasion, unreliable narration, social cognition theories of character attribution, and ideas from the study of mind style to analyse manipulation in some of Christieâs most notable works. These works include the novels Murder on the Orient Express, The Murder of Roger Ackroyd, Death in the Clouds, Cards on the Table and The ABC Murders, in addition to lesser-known short stories from The Thirteen Problems and Poirot Investigates.
More specifically, following the introduction, the analyses in Chapter 2 operate through models of the psychological processing of texts and the way that linguistic indicators are interpreted by readers. âRed herringsâ and âburied cluesâ are defined and examined using cognitive theories of schemata (information networks), scenario-dependence and a readerâs depth of processing. This is followed by Chapter 3, a rhetorical and structural analysis of persuasive practices within an extract of Christieâs fiction, where her detective Hercule Poirot attempts to convince both the assembled characters and the novelâs reader of the necessary truth of the solution he is presenting. In this chapter I introduce my own adaptation of Rhetorical Structure Theory designed for analyses of long extracts of a narrative text is also introduced. Chapter 4 looks at narratological and cognitive methods of describing character and narrator unreliability and ambiguity, through studies of an unreliable narrator, the nature of some witnessesâ minds within different novels, and the presentation of the ambiguous thoughts of an important suspect using techniques taken from the study of mind style.
The thesis aims primarily to describe and illustrate in a systematic manner a selection of the many different ways in which Christie manipulates readers, and points the way to other techniques of this sort. The breadth of the frameworks employed is intended to emphasise the range of Christieâs techniques, and to demonstrate that detective fiction contains many uses of complex manipulation which would bear further study
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