• Energy Research

Abstract Given a complex m × n matrix A, we index its singular values as σ 1 ( A ) ⩾ σ 2 ( A ) ⩾ ⋯ and call the value E ( A ) = σ 1 ( A ) + σ 2 ( A ) + ⋯ the energy of A, thereby extending the concept of graph energy, introduced by Gutman. Koolen and Moulton proved that E ( G ) ⩽ ( n / 2 ) ( 1 + n ) for any graph G of order n and exhibited an infinite family of graphs with E ( G ) = ( v ( G ) / 2 ) ( 1 + v ( G ) ) . We prove that for all sufficiently large n, there exists a graph G = G ( n ) with E ( G ) ⩾ n 3 / 2 / 2 − n 11 / 10 . This implies a conjecture of Koolen and Moulton. We also characterize all square nonnegative matrices and all graphs with energy close to the maximal one. In particular, such graphs are quasi-random.

A numerical scheme for computing the maximal energy release rate and its sensitivities is formulated. Herein, variations of design as well as variations of the constitutive law are considered.

Es wird gezeigt, wie die nicht-relativistische Bedingung fur die maximale Energie eines Teilchens - bei gleicher Geschwindigkeit aller ubrigen Teilchen -, abgeandert wird, falls eines oder mehrere Teilchen verschwindende Ruhmasse haben. Remark on the Maximal Energy of a Particle in a Three-Particle Disintegration It is shown how the non-relativistic condition for maximal energy of one particle - for equal velocities of all the others -, is modified if one or more particles have rest-mass zero.

Abstract In order to maximize the electrical energy harvested by photovoltaic panels in a setup with fixed angles, it is important to get the angle optimized. In the present work, sunlight availability or sky coverage conditions of year-long period based on ten years’ data are counted in the modeling to optimize the PV panel tilt angles targeting for the maximal energy in a year. The analysis uses precise sunray calculation models. The energy harvested in every 6 minutes by a PV panel is summated for the daily time period from sunrise to sunset when the sun elevation angles are above 5 degree, with the sky-coverage factor multiplied. The results show that the annual solar energy received by a PV solar panel tilted with a fixed angle equal to the local latitude (at Tucson AZ, USA) could reach 2297 kWh/m2 under 10-year averaged sky coverage conditions. However, the gain in the yearly solar energy harvest is expected to be about 4.28%, 7.06%, and 8.42% higher if a PV panel is inclined optimally according to two-season, four-season, and monthly adjustments, respectively, compared to the optimized life-long fixed angle.

Article provides a concept of electrical subsystem to be used to design a power-assist wheelchair. Concept development is based on analysis of commercial products to provide a more cost-effective solution. Developed concept includes battery pack, charger, drive and propulsion motors. Battery pack is designed to be easily replaceable and chargeable, while motor and drive system is developed to provide maximal energy efficiency.

We report on the first experimental implementation of a scalable M-ary quantum receiver with time-resolved photon detection and real-time adaptive displacement using off-the-shelf components. We implemented M=4, 6, 8, 12, and 16 coherent frequency shift keying communication links with optimal parameters for maximal energy sensitivity. Then, we compared the measured sensitivity with the best sensitivity that can be achieved with a perfect classical measurement (shot noise limit). We observe unconditional, below the shot-noise limit sensitivity and a favorable sensitivity scaling with the alphabet length M.