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We give a simple proof of the (perhaps not so) well known fact that exponential polynomials of order k with real exponents have at most k − 1 real zeros. We deduce several results that relate to impulsive controllability and sampled observability of finite-dimensional linear time-invariant dynamical systems. We prove that the initial state of a continuous-time linear time-invariant dynamical system of dimension n can be uniquely reconstructed from the sampled output regardless of its sampling time sequence of length n if and only if the system is observable and all the eigenvalues of the system matrix are real. This result thus characterizes sampled observability with arbitrary sampling times. Likewise, we prove that the system is controllable by means of n impulses regardless of when they occur if and only if the system is controllable and all the eigenvalues of the system matrix are real. We also show that, if the system is observable and all the eigenvalues of the system matrix are real, then there exists an initial state such that the times where the output crosses a prescribed threshold are prescribed m times with m < n. [ABSTRACT FROM AUTHOR]

This paper concerns the minimax center of a collection of linear subspaces. For k -dimensional subspaces of an n -dimensional vector space, this can be cast as finding the center of a minimum enclosing ball on a Grassmann manifold. For subspaces of differing dimension, the setting becomes a disjoint union of Grassmannians rather than a single manifold, and the problem is no longer well-defined. However, natural geometric maps exist between these manifolds with a well-defined notion of distance for the images of the subspaces under the mappings. Solving the problem in this context leads to a candidate minimax center on each of the constituent manifolds, but does not provide intuition about which candidate is the best representation of the data. Additionally, the solutions of different rank are generally not nested so a deflationary approach will not suffice, and the problem must be solved independently on each manifold. We propose an optimization problem parametrized by the rank of the minimax center. The solution is computed with a subgradient algorithm applied to the dual problem. By scaling the objective and penalizing the information lost by the rank- k minimax center, we jointly recover an optimal dimension, k ⁎ , and a subspace at the center of the minimum enclosing ball, U ⁎ , that best represents the data. [ABSTRACT FROM AUTHOR]

Low-rank matrix completion is the problem of recovering the missing entries of a data matrix by using the assumption that the true matrix admits a good low-rank approximation. Much attention has been given recently to exploiting correlations between the column/row entities to improve the matrix completion quality. In this paper, we propose preconditioned gradient descent algorithms for solving the low-rank matrix completion problem with graph Laplacian-based regularizers. Experiments on synthetic data show that our approach achieves significant speedup compared to an existing method based on alternating minimization. Experimental results on real world data also show that our methods provide low-rank solutions of similar quality in comparable or less time than the state-of-the-art method. [ABSTRACT FROM AUTHOR]

We address the numerical problem of recovering large matrices of low rank when most of the entries are unknown. We exploit the geometry of the low-rank constraint to recast the problem as an unconstrained optimization problem on a single Grassmann manifold. We then apply second-order Riemannian trust-region methods (RTRMC 2) and Riemannian conjugate gradient methods (RCGMC) to solve it. A preconditioner for the Hessian is introduced that helps control the conditioning of the problem and we detail preconditioned versions of Riemannian optimization algorithms. The cost of each iteration is linear in the number of known entries. The proposed methods are competitive with state-of-the-art algorithms on a wide range of problem instances. In particular, they perform well on rectangular matrices. We further note that second-order and preconditioned methods are well suited to solve badly conditioned matrix completion tasks. [ABSTRACT FROM AUTHOR]

Abstract: Corrosion is an essential operational factor to characterize for future demonstration and commercial carbon capture plants. In this paper, three approaches have been used to investigate corrosion in CO2 capture pilot plants: corrosion coupons, on-line monitoring and pilot plant inspection. These tests were realized in two pilot plants: Esbjerg, Dong Energy and Maasvlakte, TNO. Consistent results were obtained. In general, carbon steel and austenitic stainless steel behave well in most of the zones. Several more critical zones have been identified: stripper sump, high temperature lean solvent pipe, reboiler and reclaimer. Some corrosion mechanisms such as flow induced degradation, corrosion due to CO2 or the corrosive effect of the solvent degradation have been evidenced. [Copyright &y& Elsevier]

• Study of power losses in the economic dispatch. • Development of a method for this non-smooth and non-convex problem. • Guaranteed accuracy solution with respect to the optimal global solution. The economic dispatch problem is a fundamental problem in power system operations. An extensive body of literature has focused on providing fast and robust algorithms for solving the various instances of the economic dispatch. In order to capture physical effects such as the power losses of the network or the valve-point loading effect of combined cycle gas turbines, non-convex models of the economic dispatch have been considered. However, these features of the problem render the convergence analysis more challenging, and few methods in the literature provide insights on the global optimality of the derived solution. In this work, we propose an algorithm that efficiently provides a feasible solution, along with a lower bound, to a non-smooth and non-convex instance of the economic dispatch problem. We test our method on extensively studied test cases, and show that, in comparison with state-of-the-art methods and within a comparable computation time, it provides a solution with a much lower deviation from the power balance constraint, while furthermore producing a lower bound with an optimality gap below one percent. [ABSTRACT FROM AUTHOR]

Background: The replacement of the diseased aortic valve with a pulmonary autograft has been shown to provide excellent hemodynamic results and to be associated with low morbidity and mortality rates. Methods: From 1991 to 2005, 219 patients undergoing the Ross operation were identified. All patients underwent transthoracic echocardiography at discharge and were scheduled for a yearly study thereafter. The echocardiographic study consisted of a morphologic analysis of the pulmonary autograft with measurement of end-systolic diameters at three levels: annulus, sinuses of Valsalva, and origin of the ascending aorta 2 cm above the sinotubular junction. The dynamic analysis evaluated the function of the aortic autograft and the pulmonary homograft. Maximal and mean aortic and pulmonary transvalvular pressure gradients were investigated. Results: The 30-day mortality was 1.8% (n = 4). Cardiac deaths were not related to the autograft. The 10-year actuarial survival was 95.7% ± 2.1%. Six patients (2.8%) had grade 2 autograft valve regurgitation. No grade 3 or 4 pulmonary regurgitation was identified. At their most recent follow-up, 28 patients (13.1%) had grade 1 insufficiency of the pulmonary homograft, and 10 patients (4.6%) had a peak transvalvular gradient of 17.9 ± 10.2 mm Hg. Conclusions: Our current experience suggests that replacement of the aortic root with a pulmonary autograft can be safely performed in infants, children, and adults and is associated with low mortality and morbidity rates. It constitutes an elegant alternative to the use of prosthetic valves in the treatment of aortic valve diseases. [Copyright &y& Elsevier]

Abstract: A numerical algorithm is proposed for computing an extreme eigenpair of a symmetric/positive-definite matrix pencil . The leftmost or the rightmost eigenvalue can be targeted. Knowledge of is only required through a routine that performs matrix–vector products. The method has excellent global convergence properties and its local rate of convergence is superlinear. It is based on a constrained truncated-CG trust-region strategy to optimize the Rayleigh quotient, in the framework of a recently proposed trust-region scheme on Riemannian manifolds. [Copyright &y& Elsevier]

Abstract: Formulas are derived for the probability density function and the probability distribution function of the largest canonical angle between two p-dimensional subspaces of chosen from the uniform distribution on the Grassmann manifold (which is the unique distribution invariant by orthogonal transformations of ). The formulas involve the gamma function and the hypergeometric function of a matrix argument. [Copyright &y& Elsevier]

A continuous-time differential equation inspired by the Rayleigh quotient iteration for a symmetric matrix A is studied. The set of all continuous solutions, termed the Rayleigh quotient flow, is shown to be a time-scaled version of the Newton flow for Rayleigh quotient cost functional. The scaling factor ensures that the rate of variation of the Rayleigh quotient is constant and positive along solutions. This interpretation leads to a precise phase portrait for the Rayleigh quotient flow. It is shown that a complete (non-degenerate) solution of the Rayleigh quotient flow visits each of the eigenvectors of A in ascending order. [Copyright &y& Elsevier]

The stock of the European eel (Anguilla anguilla) is in a multi-decadal decline. Therefore, trade in European eel is now restricted by EU law and the listing in CITES Appendix II. EU law prohibits the trade of European eel across the EU's outer border and CITES regulates the global trade elsewhere. In November and December 2019, we purchased 108 eel products in 21 cities in five major eel importing countries in Europe (Germany, Belgium, Netherlands, Great Britain, France) and three online shops. All were imported from China and 73 samples were genetically identified as American eel (A. rostrata), 33 as Japanese eel (A. japonica), and a single sample each as European eel and Indian shortfin eel (A. bicolor pacifica). The one European eel sample violated the EU trade ban and CITES trade regulations. However, 28.7 % of the product labels violated EU Regulation (EU) No 1169/2011 on the provision of food information to consumers (FIC). Our results imply that Chinese exporters sell their European eel products outside the EU market and therefore avoid violating EU law. However, fraudulent labelling point at inadequate existing EU labelling requirements for prepared and preserved products and ongoing molecular genetic control of eel commodities entering the EU from China. The data that support the findings of this study are openly available in Genbank at www.ncbi.nlm.nih.gov/genbank/ under the consecutive accession numbers MN973673 - MN973780. Basic data on unagi kabayaki products are listed in Table 1, details can be obtained from the corresponding author on request. [ABSTRACT FROM AUTHOR]

• Impact of the valve point effect in the economic dispatch. • Implementation of heuristics and tests on modified benchmark problems. • Optimality gap analysis of the global solution of the non-convex problem. Gas units are becoming an increasingly important component of modern power system operations, due to the flexibility that they offer in a regime of large-scale renewable energy integration. The valve point effect refers to the loss of efficiency when operating a turbine off a valve point, that is just after the previous valve opens. The valve point effect for gas power plants is a primary attribute of their operation, however its representation raises computational challenges, due to the non-convex and non-smooth model that is required for representing the fuel cost. In this work, a new heuristic based on successive piecewise approximations of the cost function is described. This heuristic consists in two steps: first, the optimization is run over the whole feasible set and a lower bound for the optimal objective is obtained, then the feasible solutions collected in the previous step are enhanced through local searches. The approach is tested on several IEEE bus systems that have been extended with generators obeying a valve point effect. [ABSTRACT FROM AUTHOR]

Abstract: We consider the problem of approximating a rational transfer function of high degree by another rational transfer function of much smaller degree. We derive the gradients of the -norm of the approximation error and show how stationary points can be described via tangential interpolation. [Copyright &y& Elsevier]

Abstract: The economic load dispatch problem (ELDP) is a classical problem in the power systems community. It consists in the optimal scheduling of the output of power generating units to meet the required load demand subject to unit and system inequality and equality constraints. This optimization problem is challenging on three different levels: the geometry of its feasible set, the non-differentiability of its cost function and the multimodal aspect of its landscape. For this reason, ELDP has received much attention in the past few years and numerous derivative-free techniques have been proposed to tackle its multimodal and nondifferentiable characteristics. In this work we propose a different approach, exploiting the rich geometrical structure of the problem. We show that the (nonlinear) equality constraint can be handled in the framework of Riemannian manifolds and we develop a feasible (all iterates satisfy the constraints) subgradient descent algorithm to provide fast convergence to local minima. To this end, we show that Clarke’s calculus can be used to compute a deterministic admissible descent direction by solving a simple, low-dimensional quadratic program. We test our approach on four real data sets. The proposed method provides fast local convergence and scales well with respect to the problem dimension. Finally, we show that the proposed algorithm, being a local optimization method, can be incorporated in existing heuristic techniques to provide a better exploration of the search space. [Copyright &y& Elsevier]

Abstract: The multi-gate architecture is considered as a key enabler for further CMOS scaling thanks to its improved electrostatics and short-channel effect control. FinFETs represent one of the architectures of interest within that family together with Ω-gates, Π-gates, gate-all-around… They can readily be manufactured starting from SOI or bulk substrates even though more efforts have been dedicated to the SOI option so far. We report in this work an extensive benchmark of their critical electrical figures of merit (FOM) and their limitations. Both alternatives show better scalability (threshold voltage –V t vs. L) than PLANAR CMOS and exhibit similar intrinsic device performance (I off vs. I on). Introducing SOI substrates and low doped fins results in lower junction capacitance, higher mobility and voltage gain with reduced threshold voltage mismatch. Using an optimized integration to minimize parasitic capacitances and resistances we demonstrate high-performing FinFET ring-oscillators with delays down to 10ps/stage for both SOI and bulk FinFETs. SRAM cells are also reported to work, scaling similarly with the supply voltage (VDD) for the two FinFET integration schemes. [Copyright &y& Elsevier]

Abstract: We report the simultaneous improvement of both on- and off-properties for n- and p-channel MOSFETs by means of carbon co-implantation at extension level, using conventional spike annealing. For the first time, spike-annealed NFETs with phosphorus-implanted source/drain extensions (SDE) are shown to outperform conventional As-implanted devices in the deca-nanometric range. Parameters such as on-current, drain-induced barrier lowering (DIBL), external resistance (R EXT) vs. effective channel length (L eff) trade-off are examined. To obtain the full benefit of carbon co-implantation, we recommend adjusting pocket, highly doped drain (HDD) and spacer parameters. [Copyright &y& Elsevier]

Abstract: We report for the first time that the optimization of a HfSiON process on Ni-FUSI devices is best tackled using a design of experiments (DOE [Myers RH, Montgomery. Response surface methodology. New York, DC: Wiley; 1995]) approach. We show that a DOE allows for directly linking process parameters to relevant short channel performance metrics. By tuning the SiO2 thickness, HfSiO thickness, Hf concentration, nitridation parameters and by using response surface modeling (RSM), we report an improvement of 12%/17% in nMOS/pMOS drive current (I dsat 600/255uA/μm at I off =20pA/μm and V dd =1.1V) over our reference process. In parallel, we demonstrate that by selecting the right parameters, plasma nitridation can outperform thermal nitridation with NH3. We believe that this new approach will be useful for device engineers and can be easily applied. [Copyright &y& Elsevier]

Injection of manganese (Mn2+), a paramagnetic tract tracing agent and calcium analogue, into the high vocal center of starlings labeled within a few hours the nucleus robustus archistriatalis and area X as observed by in vivo magnetic resonance imaging. Structures highlighted by Mn2+ accumulation assumed the expected tri-dimensional shape of the nucleus robustus archistriatalis and area X as identified by classical histological or neurochemical methods. The volume of these nuclei could be accurately calculated by segmentation of the areas highlighted by Mn2+. Besides confirming previously established volumetric sex differences, Mn2+ uptake into these nuclei revealed new functional sex differences affecting Mn2+ transport. A faster transport was observed in males than in females and different relative amounts of Mn2+ were transported to nucleus robustus archistriatalis and area X in males as compared to females.This new in vivo approach, allowing repeated measures, opens new vistas to study the remarkable seasonal plasticity in size and activity of song-control nuclei and correlate neuronal activity with behavior. It also provides new insights on in vivo axonal transport and neuronal activity in song-control nuclei of oscines. [Copyright &y& Elsevier]