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971.
Jonathan J. Wierer Jeffrey Y. Tsao Dmitry S. Sizov 《Laser \u0026amp; Photonics Reviews》2013,7(6):963-993
Solid‐state lighting (SSL) is now the most efficient source of high color quality white light ever created. Nevertheless, the blue InGaN light‐emitting diodes (LEDs) that are the light engine of SSL still have significant performance limitations. Foremost among these is the decrease in efficiency at high input current densities widely known as “efficiency droop.” Efficiency droop limits input power densities, contrary to the desire to produce more photons per unit LED chip area and to make SSL more affordable. Pending a solution to efficiency droop, an alternative device could be a blue laser diode (LD). LDs, operated in stimulated emission, can have high efficiencies at much higher input power densities than LEDs can. In this article, LEDs and LDs for future SSL are explored by comparing: their current state‐of‐the‐art input‐power‐density‐dependent power‐conversion efficiencies; potential improvements both in their peak power‐conversion efficiencies and in the input power densities at which those efficiencies peak; and their economics for practical SSL. 相似文献
972.
973.
974.
Wenrui Hao Jonathan D. Hauenstein Bei Hu Timothy McCoy Andrew J. Sommese 《Journal of Computational and Applied Mathematics》2013
We consider a free boundary problem modeling tumor growth where the model equations include a diffusion equation for the nutrient concentration and the Stokes equation for the proliferation of tumor cells. For any positive radius R, it is known that there exists a unique radially symmetric stationary solution. The proliferation rate μ and the cell-to-cell adhesiveness γ are two parameters for characterizing “aggressiveness” of the tumor. We compute symmetry-breaking bifurcation branches of solutions by studying a polynomial discretization of the system. By tracking the discretized system, we numerically verified a sequence of μ/γ symmetry breaking bifurcation branches. Furthermore, we study the stability of both radially symmetric and radially asymmetric stationary solutions. 相似文献
975.
Jonathan D. Hauenstein 《Acta Appl Math》2013,125(1):105-119
Given a polynomial system f, a fundamental question is to determine if f has real roots. Many algorithms involving the use of infinitesimal deformations have been proposed to answer this question. In this article, we transform an approach of Rouillier, Roy, and Safey El Din, which is based on a classical optimization approach of Seidenberg, to develop a homotopy based approach for computing at least one point on each connected component of a real algebraic set. Examples are presented demonstrating the effectiveness of this parallelizable homotopy based approach. 相似文献
976.
Categorical skew lattices are a variety of skew lattices on which the natural partial order is especially well behaved. While most skew lattices of interest are categorical, not all are. They are characterized by a countable family of forbidden subalgebras. We also consider the subclass of strictly categorical skew lattices. 相似文献
977.
A novel approach to nanoparticle synthesis was developed whereby foam bubble bursting produced aerosol droplets, an approach
patterned after the marine foam aerosol cycle. The droplets were dried to remove solvent, leaving nanometer-sized particles
composed of precursor material. Nanoparticles composed of sodium chloride (mean diameter, 100 nm), phosphotungstic acid ( 55 nm), and bovine insulin ( 5–30 nm) were synthesized. Foam droplet separation can be carried out at ambient temperature and pressure. The ‘soft’ nature
of the process makes it compatible with a wide range of materials. 相似文献
978.
José Alejandro Arminio-Ravelo Anders W. Jensen Dr. Kim D. Jensen Dr. Jonathan Quinson Prof. Dr. María Escudero-Escribano 《Chemphyschem》2019,20(22):2956-2963
Proton exchange membrane water electrolysers are very promising renewable energy conversion devices that produce hydrogen from sustainable feedstocks. These devices are mainly limited by the sluggish kinetics of the oxygen evolution reaction (OER). Ir-based nanoparticles are both reasonably active and stable for the OER in acidic media. The electrolyte composition and the pH may play a crucial role in electrocatalysis, yet they have been widely overlooked for the OER. Herein, we present a study on the effects of the composition and concentration of the electrolyte on commercial Ir black nanoparticles using concentrations of 0.05 M, 0.1 M and 0.5 M of both sulphuric and perchloric acid. The results show an important effect of the electrolyte composition on the catalytic performance of the Ir nanoparticles. The concentration of H2SO4 interferes on the oxidation of Ir and decreases the catalytic performance of the catalyst. HClO4 does not show strong interferences in the electrochemistry of Ir. Higher catalytic performances are observed in HClO4 electrolytes in comparison to H2SO4 with little effect of the concentration of HClO4. 相似文献
979.
It is widely considered that, for Higgs boson searches at the CERN Large Hadron Colider, WH and ZH production where the Higgs boson decays to bb are poor search channels due to large backgrounds. We show that at high transverse momenta, employing state-of-the-art jet reconstruction and decomposition techniques, these processes can be recovered as promising search channels for the standard model Higgs boson around 120 GeV in mass. 相似文献
980.
The nature of the Extended Analog Computer 总被引:1,自引:0,他引:1
Jonathan W. Mills 《Physica D: Nonlinear Phenomena》2008,237(9):1235-1256
This paper defines the relationship between Rubel’s Extended Analog Computer (EAC) model and Indiana University’s implementation of it, a fundamental distinction that is necessary to understand the design, implementation, operation, and applications of the EAC. Beginning with the detailed structure of the current EAC, its method of computing is illustrated with diagrams and three applications. Next, the Δ-digraph, a labeled directed graph, is introduced to show how unconventional and conventional computers relate nature, mathematics and computer architecture. The Δ-digraph defines the paradigms of analogy and algorithm, illustrates how applications for the EAC are analogies developed by choosing the semantics for a machine configuration, and suggests how partial differential equations might be compiled to EAC configurations (a difficult problem compared to compiling a digital computer program, and one that is still not solved). The Δ-digraph also distinguishes between the EAC’s explicit functions (whose operation is defined in the structure of its components) and implicit functions (whose operation is inherent in the properties of matter and energy). Brief case studies show how industry and academia are adopting the EAC. The paper closes with topics and open questions for future research. 相似文献