A geometric characterization of “optimality-equivalent” relaxations

An optimization problem is defined by an objective function to be maximized with respect to a set of constraints. To overcome some theoretical and practical difficulties, the constraint-set is sometimes relaxed and “easier” problems are solved. This led us to study relaxations providing exactly the same set of optimal solutions. We give a complete characterization of these relaxations and present several examples. While the relaxations introduced in this paper are not always easy to solve, they may help to prove that some mathematical programs are equivalent in terms of optimal solutions. An example is given where some of the constraints of a linear program can be relaxed within a certain limit.     

Improving Software Performance with Configurable Logic

We examine the energy and performance benefits that can be obtained by re-mapping frequently executed loops from a microprocessor to reconfigurable logic. We present a design flow that finds critical software loops automatically and manually re-implements these inconfigurable logic by implementing them in SA-C, a C language variation supportinga dataflow computation model and designed to specify and map DSP applicationsonto reconfigurable logic. We apply this design flow on several examples fromthe MediaBench benchmark suite and report the energy and performance improvements.     

Surface équivalente radar d’objets composés de conducteur et de diélectrique de formes arbitraires

The radar cross section of metal-dielectric objects is modelized by means of an integral representation of the fields. The resulting integral equations are solved using a moment method approach applied directly to these equations or after the introduction of an approximate surface impedance boundary condition.     

Rational domain swaps decipher programming in fungal highly reducing polyketide synthases and resurrect an extinct metabolite

The mechanism of programming of iterative highly reducing polyketide synthases remains one of the key unsolved problems of secondary metabolism. We conducted rational domain swaps between the polyketide synthases encoding the biosynthesis of the closely related compounds tenellin and desmethylbassianin. Expression of the hybrid synthetases in Aspergillus oryzae led to the production of reprogrammed compounds in which the changes to the methylation pattern and chain length could be mapped to the domain swaps. These experiments reveal for the first time the origin of programming in these systems. Domain swaps combined with coexpression of two cytochrome P450 encoding genes from the tenellin biosynthetic gene cluster led to the resurrection of the extinct metabolite bassianin.     

Existence and Nonlinear Stability of Stationary States for the Semi-Relativistic Schrödinger-Poisson System

We study the stationary states of the semi-relativistic Schrödinger-Poisson system in the repulsive (plasma physics) Coulomb case. In particular, we establish the existence and the nonlinear stability of a wide class of stationary states by means of the energy-Casimir method. We generalize the global well-posedness result of (Abou Salem et al. in Dyn Partial Differ Equ 9(2):121–132, 2012) for the semi-relativistic Schrödinger-Poisson system to spaces with higher regularity.     

Comparing multi-dimensional contingency fit to financial performance of organizations

In theory, it is widely accepted that an organization’s optimal structure is contingent upon various situational factors such as market conditions, nature of work and properties of technology. In practice, providing practical advice based on this understanding has been difficult. This paper demonstrates that it is possible to find a correlation between financial performance, as measured by growth in Return on Assets, and degree of compliance with the recommendations of the contingency theory model known as Interaction Value Analysis (IVA). IVA is based on an abstract theoretical representation of organizational work as a series of value-adding interactions among rational value-maximizing agents. Six different dimensions of an organization’s situation are represented as parameters of the equation that sums up the value added by all interactions within the organization. This “Multi-dimensional” approach is contrasted with the “Multi-contingency” model, which aggregates the effects of multiple contingent-design rules without considering how the rules overlap or otherwise influence one another. The success of the six-parameter IVA model in partially predicting financial performance is an inducement to expand IVA to include more of the parameters included in the Multi-contingency model.     

802GHz integrated horn antennas imaging array

This short paper presents the pattern measurements at 802GHz of a single element in a 256-element integrated horn imaging array. The integrated-horn antenna consists of a dipole-antenna suspended on a 1μm dielectric membrane inside a pyramidal cavity etched in Silicon. The theoretical far-field patterns, calculated using reciprocity and Floquet-modes representation of the free-space field, agree well with the measured far-field patterns at 802GBz. The associated directivity for a 1.40 λ horn aperture, calculated from the measured E and H-plane patterns is 12.3dB±0.2dB. This work demonstrates that high-efficiency integrated-horn antennas are easily scalable to terahertz frequencies and could be used for radio-astronomical and plasma-diagnostic applications.     

Computing the Initial Temperature of Simulated Annealing

The classical version of simulated annealing is based on a cooling schedule. Generally, the initial temperature is set such that the acceptance ratio of bad moves is equal to a certain value ₀. In this paper, we first propose a simple algorithm to compute a temperature which is compatible with a given acceptance ratio. Then, we study the properties of the acceptance probability. It is shown that this function is convex for low temperatures and concave for high temperatures. We also provide a lower bound for the number of plateaux of a simulated annealing based on a geometric cooling schedule. Finally, many numerical experiments are reported.     

Synthesis of single-phase anatase nanocrystallites at near room temperatures

Single-phase aqueous solutions of nanocrystalline anatase titanium dioxide were produced under ambient pressure and at a temperature as low as 38 degree C using the sol-gel process.     

Transparent and Flexible Mn1−x−y(CexLay)O2−δ Ultrathin-Film Device for Highly-Stable Pseudocapacitance Application

Control over the fabrication of state-of-the-art portable pseudocapacitors with the desired transparency, mechanical flexibility, capacitance, and durability is challenging, but if resolved will have fundamental implications. Here, defect-rich Mn_1−x−y(Ce_xLa_y)O_2−δ ultrathin films with controllable thicknesses (5–627 nm) and transmittance (≈29–100%) are fabricated via an electrochemical chronoamperometric deposition using a aqueous precursor derived from end-of-life nickel-metal hydride batteries. Due to percolation impacts on the optoelectronic properties of ultrathin films, a representative Mn_1−x−y(Ce_xLa_y)O_2−δ film with 86% transmittance exhibits an outstanding areal capacitance of 3.4 mF cm⁻², mainly attributed to the intercalation/de-intercalation of anionic O²⁻ through the atomic tunnels of the stratified Mn_1−x−y(Ce_xLa_y)O_2−δ crystallites. Furthermore, the Mn_1−x−y(Ce_xLa_y)O_2−δ thin-film device exhibits excellent capacitance retention of ≈90% after 16 000 cycles. Such stability is associated with intervalence charge transfer occurring among interstitial Ce/La cations and Mn oxidation states within the Mn_1−x−y(Ce_xLa_y)O_2−δ structure. The energy and power densities of the transparent flexible Mn_1−x−y(Ce_xLa_y)O_2−δ full-cell pseudocapacitor device, is measured to be 0.088 μWh cm⁻² and 843 µW cm⁻², respectively. These values show insignificant changes under vigorous twisting and bending to 45–180° confirming these value-added materials are intriguing alternatives for size-sensitive energy storage devices.