Conditions for the uniqueness of the optimal solution in linear semi-infinite programming

In this paper, we establish different conditions for the uniqueness of the optimal solution of a semi-infinite programming problem. The approach here is based on the differentiability properties of the optimal value function and yields the corresponding extensions to the general linear semi-infinite case of many results provided by Mangasarian and others. In addition, detailed optimality conditions for the most general problem are supplied, and some features of the optimal set mapping are discussed. Finally, we obtain a dimensional characterization of the optimal set, provided that a usual closedness condition (Farkas-Minkowski condition) holds.     

Caballero: a high current flux compressor system for 100 MJ solidliner experiments

Pulse power systems delivering in excess of 100 MJ represent one of the next major challenges to the community. While laboratory pulse power systems in this energy range are feasible, they represent very substantial investments of both time and resources. Prudence requires that fundamental proof of principle for the contemplated application be established before such massive resources are committed. Explosive pulse power systems using magnetic flux compression provide a direct path to such demonstrations. Furthermore, as energy requirements grow, they may represent the only affordable source of ultra-high energy environments. In this paper we report the results of an experimental test of a first generation disk generator system. Individual disk segments have been tested with framing camera diagnostics to evaluate overall performance dynamics and material, and fabrication failure points. In general no bulk failures were observed in several shots and the critical weld joints were seen to maintain integrity for at least 4 μs after arrival of the detonation front. Single module pulse power experiments have been conducted at reduced initial current (1.5-2.0 MA) with a fixed inductance load of 0.22 nH     

A lower bound to the π0π0 S-wave scattering length

A new lower bound to the π⁰π⁰ S-wave scattering length is found in terms of the D-wave scattering length. The main ingredients of the method are the Roy exact partial-wave equations and an extensive use of unitarity in the physical region. For a value of a₂ = 7.3 × 10^?4, we get the bound a₀ ? ?0.33.     

Universal fluctuations in correlated systems

The probability density function (PDF) of a global measure in a large class of highly correlated systems has been suggested to be of the same functional form. Here, we identify the analytical form of the PDF of one such measure, the order parameter in the low temperature phase of the 2D XY model. We demonstrate that this function describes the fluctuations of global quantities in other correlated equilibrium and nonequilibrium systems. These include a coupled rotor model, Ising and percolation models, models of forest fires, sandpiles, avalanches, and granular media in a self-organized critical state. We discuss the relationship with both Gaussian and extremal statistics.     

Enhanced critical currents of superconducting ErNi2B2C in the ferromagnetically ordered state

We report on transport and magnetization studies of the critical current in single crystal ErNi2B2C for applied fields below 4 kG. Below T approximately 2.5 K superconductivity coexists with weak ferromagnetism. We find that the critical currents are strongly enhanced for all field orientations in this ferromagnetic regime, corresponding to a threefold increase of the pinning force of the flux line lattice. We speculate that this increase is due to strong pair breaking by the ferromagnetism.     

Growth, morphological and structural characterization of Pb1−xSnxTe single crystals

Pb_1−xSn_xTe single crystals have been grown by a vertical Bridgman method. They have typical Hall mobilities and carrier concentration values of 10³ cm²/V · s and 10¹⁸ cm^-3, respectively, and change from p- to n-type as the Sn content increases. The ingots were single crystal with a subgrain structure that has a misorientation no higher than 2′. The segregation of Sn has been determined and it suggests that there is a convective flow in the liquid.     

An N‐Heterocyclic‐Carbene‐Derived Distonic Radical Cation

We present the discovery of a novel radical cation formed through one‐electron oxidation of an N‐heterocyclic carbene–carbodiimide (NHC–CDI) zwitterionic adduct. This compound possesses a distonic electronic structure (spatially separate spin and charge regions) and displays persistence under ambient conditions. We demonstrate its application in a redox‐flow battery exhibiting minimal voltage hysteresis, a flat voltage plateau, high Coulombic efficiency, and no performance decay for at least 100 cycles. The chemical tunability of NHCs and CDIs suggests that this approach could provide a general entry to redox‐active NHC–CDI adducts and their persistent radical ions for various applications.