Sufficient Second Order Optimality Conditions for C^1 Multiobjective Optimization Problems

2000 Mathematics Subject Classification: Primary 90C29; Secondary 90C30.

Oscillation Criteria for Nonlinear Differential Equations of Second Order with Damping Term

2000 Mathematics Subject Classification: 34C10, 34C15.

Interval Oscillation for Second Order Nonlinear Differential Equations with a Damping Term

2000 Mathematics Subject Classification: 34C10, 34C15.

Oscillation Criteria of Second-Order Quasi-Linear Neutral Delay Difference Equations

2000 Mathematics Subject Classification: 39A10.

Effect of second order signal-noise interactions in nonlinearity compensated optical transmission systems

In this Letter, we theoretically and numerically analyze the performance of coherent optical transmission systems that deploy inline or transceiver based nonlinearity compensation techniques. For systems where signal-signal nonlinear interactions are fully compensated, we find that beyond the performance peak the signal-to-noise ratio degradation has a slope of 3 dBSNR/dBPower suggesting a quartic rather than quadratic dependence on signal power. This is directly related to the fact that signals in a given span will interact not only with linear amplified spontaneous emission noise, but also with the nonlinear four-wave mixing products generated from signal-noise interaction in previous (hitherto) uncompensated spans. The performance of optical systems employing different nonlinearity compensation schemes were numerically simulated and compared against analytical predictions, showing a good agreement within a 0.4 dB margin of error.

Brillouin optical time-domain analysis assisted by second-order Raman amplification

We propose and experimentally demonstrate a new method to extend the range of Brillouin optical time domain analysis (BOTDA) systems. It exploits the virtual transparency created by second-order Raman pumping in optical fibers. The idea is theoretically analyzed and experimentally demonstrated in a 50 km fiber. By working close to transparency, we also show that the measurement length of the BOTDA can be increased up to 100 km with 2 meter resolution. We envisage extensions of this technique to measurement lengths well beyond this value, as long as the issue of relative intensity noise (RIN) of the primary Raman pump can be avoided. © 2010 Optical Society of America.

A projektek és a változtatások szerepelméleteinek összehasonlítása (Comparison of role concepts of projects and changes)

A szerzők jelen cikkükben a projektmenedzsment és a változásmenedzsment szakirodalmában olvasható szerepelméleteket hasonlítják össze. A hasonlóságok szembeötlőek, de nem nyilvánvaló, hogy az egyes definíciók pontosan miben egyeznek vagy térnek el egymástól. A két szakterület irodalmában nem találtak ilyen összehasonlító elemzést. Először összehasonlítják a projekt, az elsőfokú (morfostatikus) és a másodfokú (morfogenetikus) változás közkeletű definícióit, hogy körülhatárolhassák a közöttük lévő átfedéseket, ahol egyáltalán van értelme összevetniük a különböző szerepmeghatározásokat. Találnak közöttük átfedést, ahol a különböző szerepdefiníciók egyaránt érvényesek, így összehasonlíthatók egymással. A két szakterület szerepmeghatározásainak tartalmát elemezve teljes egyezések, részleges hasonlóságok és különbségek is találhatók. Legfontosabb megállapításuk az, hogy a tartalmi átfedések és kapcsolódások miatt mindkét szakterület oktatói, kutatói és gyakorlati művelői komoly haszonnal forgathatják a másik terület szerepelméleti szakirodalmát is. ________ This paper compares the role concepts which are in current use in project management and change management literature. The similarities are noticeable at first sight but it is not clear where the domains of the different definitions of the two management disciplines overlap and where they vary from each other significantly. The authors have not found such an interdisciplinary comparison in the literature of the two fields. At first, they compared the widely used definitions of project, first order (or morphostatic) and second order (or morphogenetic) changes to find the overlapping areas where it is reasonable to compare the different role definitions at all. They found an overlapping area where the different role definitions are all valid and the role theories can be compared. The typical project stakeholders are: project sponsor, project manager, project management team, project team, influencers, customer/user, performing organization etc. The typical change roles are: sponsor (initiating and sustaining), agent, target, advocate, facilitator etc. The authors found samenesses, similarities and differences alike between the two sets of roles. The most important conclusion is that the findings enable participants working on these types of activities to rely on both bodies of knowledge properly.

Principal component and second generation wavelet analysis of Treasury yield curve evolution

Prices of U.S. Treasury securities vary over time and across maturities. When the market in Treasurys is sufficiently complete and frictionless, these prices may be modeled by a function time and maturity. A cross-section of this function for time held fixed is called the yield curve; the aggregate of these sections is the evolution of the yield curve. This dissertation studies aspects of this evolution. ^ There are two complementary approaches to the study of yield curve evolution here. The first is principal components analysis; the second is wavelet analysis. In both approaches both the time and maturity variables are discretized. In principal components analysis the vectors of yield curve shifts are viewed as observations of a multivariate normal distribution. The resulting covariance matrix is diagonalized; the resulting eigenvalues and eigenvectors (the principal components) are used to draw inferences about the yield curve evolution. ^ In wavelet analysis, the vectors of shifts are resolved into hierarchies of localized fundamental shifts (wavelets) that leave specified global properties invariant (average change and duration change). The hierarchies relate to the degree of localization with movements restricted to a single maturity at the base and general movements at the apex. Second generation wavelet techniques allow better adaptation of the model to economic observables. Statistically, the wavelet approach is inherently nonparametric while the wavelets themselves are better adapted to describing a complete market. ^ Principal components analysis provides information on the dimension of the yield curve process. While there is no clear demarkation between operative factors and noise, the top six principal components pick up 99% of total interest rate variation 95% of the time. An economically justified basis of this process is hard to find; for example a simple linear model will not suffice for the first principal component and the shape of this component is nonstationary. ^ Wavelet analysis works more directly with yield curve observations than principal components analysis. In fact the complete process from bond data to multiresolution is presented, including the dedicated Perl programs and the details of the portfolio metrics and specially adapted wavelet construction. The result is more robust statistics which provide balance to the more fragile principal components analysis. ^

Entering an academic discourse community: A case study of the coping strategies of eleven english as a second language students

This case study follows eleven non-English speaking students as they adapt to community college, content courses. The three classes examined are required freshman classes--Humanities, Social Environment, and Individual in Transition. In order to cope with the demands of these classes, students must penetrate the academic discourse community and have effective relationships with their instructors and their peers. The results of the study are based on interviews with eleven non-native speaking (NNS) students and their instructors and on an analysis of student writing assignments, course syllabi, and exams. Three general areas are examined: (a) students' first-language (L1) education, (b) the requirements of their content classes, and (c) the affective factors which influence their adaptation process. The case of these students reveals that: 1. Students draw on their L1 education, especially in terms of content, as they cope with the demands of these content classes. 2. In some areas L1 educational experiences interfere with students' ability to adapt. 3. The content classes require students to have well developed reading, writing, oral, and aural skills. 4. Students must use higher level cognitive skills to be successful in content classes. 5. Affective factors play a role in students' success in content classes. The discussion section includes possible implications of this data for college level English as a Second Language courses.

Solitons in Exciton-Polariton System: Reduced Modelling, Analysis, and Numerical Studies

In this dissertation, we study the behavior of exciton-polariton quasiparticles in semiconductor microcavities, under the sourceless and lossless conditions.

First, we simplify the original model by removing the photon dispersion term, thus effectively turn the PDEs system to an ODEs system,

and investigate the behavior of the resulting system, including the equilibrium points and the wave functions of the excitons and the photons.

Second, we add the dispersion term for the excitons to the original model and prove that the band of the discontinuous solitons now become dark solitons.

Third, we employ the Strang-splitting method to our sytem of PDEs and prove the first-order and second-order error bounds in the $H^1$ norm and the $L_2$ norm, respectively.

Using this numerical result, we analyze the stability of the steady state bright soliton solution. This solution revolves around the $x$-axis as time progresses

and the perturbed soliton also rotates around the $x$-axis and tracks closely in terms of amplitude but lags behind the exact one. Our numerical result shows orbital

stability but no $L_2$ stability.

Second-Order Risk Constraints

This paper discusses how numerically imprecise information can be modelled and how a risk evaluation process can be elaborated by integrating procedures for numerically imprecise probabilities and utilities. More recently, representations and methods for stating and analysing probabilities and values (utilities) with belief distributions over them (second order representations) have been suggested. In this paper, we are discussing some shortcomings in the use of the principle of maximising the expected utility and of utility theory in general, and offer remedies by the introduction of supplementary decision rules based on a concept of risk constraints taking advantage of second-order distributions.

Upper Secondary Students’ Beliefs About Learning English as a Foreign Language : A contrast between the students’ beliefs and the Swedish curriculum

Learning English as a foreign language (EFL) entails different factors. Language learners use different strategies in order to make their language acquisition successful. Motivation and self-regulated learning are other factors that influence how successful the EFL learner is. This paper aims to analyze the beliefs of upper secondary students in a Swedish school about learning EFL, as well as how their beliefs relate to what is specified in the Swedish curriculum. An analysis of the differences between students’ beliefs and what is stated in the curriculum was done. A survey was conducted on a total of 54 students who were enrolled in the social sciences program. The results showed that students believed that motivation and self-regulated learning were important factors for a successful learning. For them, the language skill of reception is more important than production, which does not correspond with what it is stated in the national curriculum. First and second year students’ beliefs were similar in most of the cases, but not all of them.

A Posteriori Error Analysis of hp-Version Discontinuous Galerkin Finite Element Methods for Second-Order Quasilinear Elliptic Problems

We develop the a-posteriori error analysis of hp-version interior-penalty discontinuous Galerkin finite element methods for a class of second-order quasilinear elliptic partial differential equations. Computable upper and lower bounds on the error are derived in terms of a natural (mesh-dependent) energy norm. The bounds are explicit in the local mesh size and the local degree of the approximating polynomial. The performance of the proposed estimators within an automatic hp-adaptive refinement procedure is studied through numerical experiments.

Uniform second-order solution for supersonic flow over delta wing using reverse-flow integral method,

"CM-1034."

Three-dimensional kinetic simulations of active suspensions: effect of chemotaxis and steric interaction

In this work, the effects of chemotaxis and steric interactions in active suspensions are analyzed by extending the kinetic model proposed by Saintillan and Shelley [1, 2]. In this model, a conservation equation for the active particle configuration is coupled to the Stokes equation for the flow arising from the force dipole exerted by the particles on the fluid. The fluid flow equations are solved spectrally and the conservation equation is solved by second-order finite differencing in space and second-order Adams-Bashforth time marching. First, the dynamics in suspensions of oxytactic run-and-tumble bacteria confined in thin liquid films surrounded by air is investigated. These bacteria modify their tumbling behavior by making temporal comparisons of the oxygen concentration, and, on average, swim towards high concentrations of oxygen. The kinetic model proposed by Saintillan and Shelley [1, 2] is modified to include run-and-tumble effects and oxygentaxis. The spatio-temporal dynamics of the oxygen and bacterial concentration are analyzed. For small film thicknesses, there is a weak migration of bacteria to the boundaries, and the oxygen concentration is high inside the film as a result of diffusion; both bacterial and oxygen concentrations quickly reach steady states. Above a critical film thickness (approximately 200 micron), a transition to chaotic dynamics is observed and is characterized by turbulent-like 3D motion, the formation of bacterial plumes, enhanced oxygen mixing and transport into the film, and hydrodynamic velocities of magnitudes up to 7 times the single bacterial swimming speed. The simulations demonstrate that the combined effects of hydrodynamic interactions and oxygentaxis create collective three-dimensional instabilities which enhances oxygen availability for the bacteria. Our simulation results are consistent with the experimental findings of Sokolov et al. [3], who also observed a similar transition with increasing film thickness. Next, the dynamics in concentrated suspensions of active self-propelled particles in a 3D periodic domain are analyzed. We modify the kinetic model of Saintillan and Shelley [1, 2] by including an additional nematic alignment torque proportional to the local concentration in the equation for the rotational velocity of the particles, causing them to align locally with their neighbors (Doi and Edwards [4]). Large-scale three- dimensional simulations show that, in the presence of such a torque both pusher and puller suspensions are unstable to random fluctuations and are characterized by highly nematic structures. Detailed measures are defined to quantify the degree and direction of alignment, and the effects of steric interactions on pattern formation will be presented. Our analysis shows that steric interactions have a destabilizing effect in active suspensions.