766 research outputs found
New data acquisition system records bearing measurements directly
Digital data acquisition system records steady state and dynamic data of bearing and shaft displacement. Elliptical orbits formed can be reconstructed and the data reduced automatically. System also reads pressures, temperatures, flows, and torque during any one data scan
New developments on free electron lasers based on self-amplified spontaneous emission
After a brief introduction to the basic concept of Free Electron Lasers operating in the Self-Amplified Spontaneous Emission (SASE) mode, the paper presents the rapid progress achieved during the past 3 years in successfully proving this FEL process at shorter and shorter wavelengths, meanwhile reaching 80 nm. The technical challenges are discussed to be overcome in building FEL facilities for wavelengths much below the visible, and these challenges are compared with the present state-of-the-art. Finally, approved and proposed SASE FEL projects are briefly summarized
Linac-based free electron laser
A basic treatment of the principle of the linac-driven free-electron laser (FEL) is given. The first part of the paper describes the FEL in low-gain approximation, and in the second part the high-gain FEL theory is given. The majority of the treatment describes FELs in one dimensional approximation, neglecting effects by diffraction of radiation and by electron beam emittance. Only in the final section a few remarks on these issues are given. The ambition of the paper is by no means any progress in FEL theory but a clear presentation of basic FEL theory concepts with explicit derivation of the formulae from first principles
Potassium topping cycles for stationary power
A design study was made of the potassium topping cycle powerplant for central station use. Initially, powerplant performance and economics were studied parametrically by using an existing steam plant as the bottom part of the cycle. Two distinct powerplants were identified which had good thermodynamic and economic performance. Conceptual designs were made of these two powerplants in the 1200 MWe size, and capital and operating costs were estimated for these powerplants. A technical evaluation of these plants was made including conservation of fuel resources, environmental impact, technology status, and degree of development risk. It is concluded that the potassium topping cycle could have a significant impact on national goals such as air and water pollution control and conservation of natural resources because of its higher energy conversion efficiency
Hydrodynamic journal bearing test and analysis
Hydrodynamic journal bearing test and analysi
InP-quantum dots in Al0.20Ga0.80InP with different barrier configurations
Systematic ensemble photoluminescence studies have been performed on type-I
InP-quantum dots in Al0.20Ga0.80InP barriers, emitting at approximately 1.85 eV
at 5 K. The influence of different barrier configurations as well as the
incorporation of additional tunnel barriers on the optical properties has been
investigated. The confinement energy between the dot barrier and the
surrounding barrier layers, which is the sum of the band discontinuities for
the valence and the conduction bands, was chosen to be approximately 190 meV by
using Al0.50Ga0.50InP. In combination with 2 nm thick AlInP tunnel barriers,
the internal quantum efficiency of these barrier configurations can be
increased by up to a factor of 20 at elevated temperatures with respect to
quantum dots without such layers.Comment: physica status solidi (c) (Proceedings of QD 2008
Using the new products margin to predict the industry-level impact of trade reform
This paper develops a methodology for predicting the impact of trade liberalization on exports by industry (3-digit ISIC) based on the pre-liberalization distribution of exports by product (5-digit SITC). Using the results of Kehoe and Ruhl (2013) that much of the growth in trade after trade liberalization is in products that are traded very little or not at all, we predict that industries with a higher share of exports generated by least traded products will experience more growth. Using our methodology, we develop predictions for industry-level changes in trade for the United States and Korea following the U.S.-Korea Free Trade Agreement (KORUS). As a test for our methodology, we show that it performs significantly better than the applied general equilibrium models originally used for the policy evaluation of the North American Free Trade Agreement (NAFTA)
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