9,440 research outputs found
Developing integrated parametric planning models for budgeting and managing complex projects
The applicability of integrated parametric models for the budgeting and management of complex projects is investigated. Methods for building a very flexible, interactive prototype for a project planning system, and software resources available for this purpose, are discussed and evaluated. The prototype is required to be sensitive to changing objectives, changing target dates, changing costs relationships, and changing budget constraints. To achieve the integration of costs and project and task durations, parametric cost functions are defined by a process of trapezoidal segmentation, where the total cost for the project is the sum of the various project cost segments, and each project cost segment is the integral of a linearly segmented cost loading function over a specific interval. The cost can thus be expressed algebraically. The prototype was designed using Lotus-123 as the primary software tool. This prototype implements a methodology for interactive project scheduling that provides a model of a system that meets most of the goals for the first phase of the study and some of the goals for the second phase
Josephson effect between superconducting nanograins with discrete energy levels
We investigate the Josephson effect between two coupled superconductors,
coupled by the tunneling of pairs of electrons, in the regime that their energy
level spacing is comparable to the bulk superconducting gap, but neglecting any
charging effects. In this regime, BCS theory is not valid, and the notion of a
superconducting order parameter with a well-defined phase is inapplicable.
Using the density matrix renormalization group, we calculate the ground state
of the two coupled superconductors and extract the Josephson energy. The
Josephson energy is found to display a reentrant behavior (decrease followed by
increase) as a function of increasing level spacing. For weak Josephson
coupling, a tight-binding approximation is introduced, which illustrates the
physical mechanism underlying this reentrance in a transparent way. The DMRG
method is also applied to two strongly coupled superconductors and allows a
detailed examination of the limits of validity of the tight-binding model
Controlling Behaviors in Middle School Youth’s Dating Relationships: Reactions and Help-Seeking Behaviors
This exploratory study examined middle school students’ (N = 380) help-seeking behaviors and other reactions to controlling behaviors in their dating relationships. Over three-fourths of the participants perpetrated and were victimized by controlling behaviors in their dating relationships. Youth used emotional/verbal and dominance/isolation forms of controlling behaviors. More youth were victimized by dominance/isolation controlling behaviors than emotional/verbal controlling behaviors. Gender and age differences emerged when evaluating the type of controlling behaviors youth used. The majority of youth were willing to seek help when confronted with various types of controlling behaviors in their dating relationships. Gender and age differences also emerged in youth’s reactions to controlling behaviors. More understanding of youth’s reactions to controlling behaviors in their dating relationships may assist prevention educators in intervening before controlling behaviors in dating relationships turn into actual dating violence
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A study of four methods of computing analysis of variance on a two-way design fixed-model with disproportionate cell frequencies
This study sought to determine the effect of varying degrees of disproportionality of four methods of handling disproportionality cell frequencies in two-way analysis of variance. A Monte Carlo simulation procedure was employed. Two multiple linear regression techniques and two "approximate" techniques were compared
Analysis of Dialogical Argumentation via Finite State Machines
Dialogical argumentation is an important cognitive activity by which agents
exchange arguments and counterarguments as part of some process such as
discussion, debate, persuasion and negotiation. Whilst numerous formal systems
have been proposed, there is a lack of frameworks for implementing and
evaluating these proposals. First-order executable logic has been proposed as a
general framework for specifying and analysing dialogical argumentation. In
this paper, we investigate how we can implement systems for dialogical
argumentation using propositional executable logic. Our approach is to present
and evaluate an algorithm that generates a finite state machine that reflects a
propositional executable logic specification for a dialogical argumentation
together with an initial state. We also consider how the finite state machines
can be analysed, with the minimax strategy being used as an illustration of the
kinds of empirical analysis that can be undertaken.Comment: 10 page
Low-frequency noise as a source of dephasing of a qubit
With the growing efforts in isolating solid-state qubits from external
decoherence sources, the material-inherent sources of noise start to play
crucial role. One representative example is electron traps in the device
material or substrate. Electrons can tunnel or hop between a charged and an
empty trap, or between a trap and a gate electrode. A single trap typically
produces telegraph noise and can hence be modeled as a bistable fluctuator.
Since the distribution of hopping rates is exponentially broad, many traps
produce flicker-noise with spectrum close to 1/f. Here we develop a theory of
decoherence of a qubit in the environment consisting of two-state fluctuators,
which experience transitions between their states induced by interaction with
thermal bath. Due to interaction with the qubit the fluctuators produce
1/f-noise in the qubit's eigenfrequency. We calculate the results of qubit
manipulations - free induction and echo signals - in such environment. The main
problem is that in many important cases the relevant random process is both
non-Markovian and non-Gaussian. Consequently the results in general cannot be
represented by pair correlation function of the qubit eigenfrequency
fluctuations. Our calculations are based on analysis of the density matrix of
the qubit using methods developed for stochastic differential equations. The
proper generating functional is then averaged over different fluctuators using
the so-called Holtsmark procedure. The analytical results are compared with
simulations allowing checking accuracy of the averaging procedure and
evaluating mesoscopic fluctuations. The results allow understanding some
observed features of the echo decay in Josephson qubits.Comment: 18 pages, 8 figures, Proc. of NATO/Euresco Conf. "Fundamental
Problems of Mesoscopic Physics: Interactions and Decoherence", Granada,
Spain, Sept.200
Readout of GEM Detectors Using the Medipix2 CMOS Pixel Chip
We have operated a Medipix2 CMOS readout chip, with amplifying, shaping and
charge discriminating front-end electronics integrated on the pixel-level, as a
highly segmented direct charge collecting anode in a three-stage gas electron
multiplier (Triple-GEM) to detect the ionization from Fe X-rays and
electrons from Ru. The device allows to perform moderate energy
spectroscopy measurements (20 % FWHM at 5.9 keV -rays) using only digital
readout and two discriminator thresholds. Being a truly 2D-detector, it allows
to observe individual clusters of minimum ionizing charged particles in
(70:30) and (70:30) mixtures and to achieve excellent
spatial resolution for position reconstruction of primary clusters down to
, based on the binary centroid determination method.Comment: 18 pages, 14 pictures. submitted to Nuclear Instruments and Methods
in Physics Research
Option pricing and perfect hedging on correlated stocks
We develop a theory for option pricing with perfect hedging in an inefficient
market model where the underlying price variations are autocorrelated over a
time tau. This is accomplished by assuming that the underlying noise in the
system is derived by an Ornstein-Uhlenbeck, rather than from a Wiener process.
With a modified portfolio consisting in calls, secondary calls and bonds we
achieve a riskless strategy which results in a closed expression for the
European call price which is always lower than Black-Scholes price. We also
obtain a partial differential equation for the option price and study the
sensitivity to several parameters and the risk of the dynamics of the call
price.Comment: 36 pages, 8 figures, 2 table
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