Conserved- and zero-mean quadratic quantities in oscillatory systems

We study quadratic functionals of the variables of a linear oscillatory system and their derivatives. We show that such functionals are partitioned in conserved quantities and in trivially- and intrinsic zero-mean quantities. We also state an equipartition of energy principle for oscillatory systems

State maps for linear systems

Modeling of physical systems consists of writing the equations describing a phenomenon and yields as a result a set of differential-algebraic equations. As such, state-space models are not a natural starting point for modeling, while they have utmost importance in the simulation and control phase. The paper addresses the problem of computing state variables for systems of linear differential-algebraic equations of various forms. The point of view from which the problem is considered is the behavioral one, as put forward in [J. C. Willems, Automatica J. IFAC, 22 (1986), pp. 561–580; DynamicsReported,2(1989),pp.171–269;IEEETrans.Automat.Control,36(1991),pp. 259–294]

Exclusivity as Inefficient Insurance

It is well established that an incumbent firm may use exclusivity contracts so as to monopolize an industry or deter entry. Such an anticompetitive practice could be tolerated if it were associated with sufficiently large efficiency gains, e.g. insuring buyers against price volatility. In this paper we study the trade-off between positive effects (risk sharing) and negative effects (exclusion) of exclusivity contracts. We revisit the seminal model of Aghion and Bolton (1987) under risk-aversion and show that although exclusivity contracts induce optimal risk-sharing, they can be used not only to deter the entry of a more efficient rival on the product market but also to crowd out financial investors willing to insure the buyer at competitive rates. We further show that in a world without financial investors, purely financial bilateral instruments, such as forward contracts, achieve optimal risk sharing without distorting product market outcomes. Thus, there is no room for an insurance defense of exclusivity contracts.exclusivity;contracts;monopolization;risk-aversion;risk-sharing;damages

Exclusion Through Speculation

Many commodities are traded on both a spot market and a derivative market. We show that an incumbent producer may use financial derivatives to extract rent from a potential entrant. The incumbent can indeed sell insurance to a large buyer to commit himself to compete aggressively in the spot market and drive the price down for the entrant. It can do so by selling derivatives for more than his expected production level, i.e. by taking a speculative position. This comes at the cost of inefficiently deterring entry.exclusion;monopolization;contracts;financial contracts;derivatives;risk aversion;speculation

An investigation of dynamic instability of stiffened rectangular plates

Boundaries of regions of parametric instability of simply supported stiffened rectangular plat

An investigation of the parametric resonance of rectangular plates reinforced with closely spaced stiffeners

Parametric resonance and structural stability model of uniformly reinforced flat plate

Singularity-sensitive gauge-based radar rainfall adjustment methods for urban hydrological applications

Gauge-based radar rainfall adjustment techniques have been widely used to improve the applicability of radar rainfall estimates to large-scale hydrological modelling. However, their use for urban hydrological applications is limited as they were mostly developed based upon Gaussian approximations and therefore tend to smooth off so-called "singularities" (features of a non-Gaussian field) that can be observed in the fine-scale rainfall structure. Overlooking the singularities could be critical, given that their distribution is highly consistent with that of local extreme magnitudes. This deficiency may cause large errors in the subsequent urban hydrological modelling. To address this limitation and improve the applicability of adjustment techniques at urban scales, a method is proposed herein which incorporates a local singularity analysis into existing adjustment techniques and allows the preservation of the singularity structures throughout the adjustment process. In this paper the proposed singularity analysis is incorporated into the Bayesian merging technique and the performance of the resulting singularity-sensitive method is compared with that of the original Bayesian (non singularity-sensitive) technique and the commonly used mean field bias adjustment. This test is conducted using as case study four storm events observed in the Portobello catchment (53 km2) (Edinburgh, UK) during 2011 and for which radar estimates, dense rain gauge and sewer flow records, as well as a recently calibrated urban drainage model were available. The results suggest that, in general, the proposed singularity-sensitive method can effectively preserve the non-normality in local rainfall structure, while retaining the ability of the original adjustment techniques to generate nearly unbiased estimates. Moreover, the ability of the singularity-sensitive technique to preserve the non-normality in rainfall estimates often leads to better reproduction of the urban drainage system's dynamics, particularly of peak runoff flows

Deep level transient spectroscopy study for the development of ion-implanted silicon field-effect transistors for spin-dependent transport

A deep level transient spectroscopy (DLTS) study of defects created by low-fluence, low-energy ion implantation for development of ion-implanted silicon field-effect transistors for spin-dependent transport experiments is presented. Standard annealing strategies are considered to activate the implanted dopants and repair the implantation damage in test metal-oxide-semiconductor (MOS) capacitors. Fixed oxide charge, interface trapped charge and the role of minority carriers in DLTS are investigated. A furnace anneal at 950 $\rm ^{o}$C was found to activate the dopants but did not repair the implantation damage as efficiently as a 1000 $\rm ^{o}$C rapid thermal anneal. No evidence of bulk traps was observed after either of these anneals. The ion- implanted spin-dependent transport device is shown to have expected characteristics using the processing strategy determined in this study.Comment: 4 pages, 6 figure