5,780 research outputs found

    Evaluation of management strategies for the operation of high-speed railways in China

    Get PDF
    High-Speed Train (HST) operations have recently been introduced in rail passenger transportation markets worldwide. Although the technologies for such operations have levelled at speeds of around 300 km/h, the operating parameters to be adopted in each application will differ from country to country. The operating environment will be one of the crucial success factors for the implementation of HST operations in China. This paper compares three different management/ownership models which might be used in China. The paper analyzes the characteristics of each model and proposes an optimal plan of an operational system to develop HST operations in China by using a hierarchy goals achievement matrix approach

    Synthesis of a Molecular Charm Bracelet via Click Cyclization and Olefin Metathesis Clipping

    Get PDF
    We describe the synthesis of a polycatenated cyclic polymer, a structure that resembles a molecular charm bracelet. Ruthenium-catalyzed ring-opening metathesis polymerization of an aminocontaining cyclic olefin monomer in the presence of a chain transfer agent generated an α,ω-diazide functionalized polyamine. Cyclization of the resulting linear polyamine using pseudo-high-dilution coppercatalyzed click cyclization produced a cyclic polymer in 19% yield. The click reaction was then further employed to remove linear contaminants from the cyclic polymer using azide- and alkyne-functionalized scavenging resins, and the purified cyclic polymer product was characterized by gel permeation chromatography, ^1H NMR spectroscopy, and IR spectroscopy. Polymer hydrogenation and conversion to the corresponding polyammonium species enabled coordination and interlocking of diolefin polyether fragments around the cyclic polymer backbone using ruthenium-catalyzed ring-closing olefin metathesis to afford a molecular charm bracelet structure. This charm bracelet complex was characterized by ^1H NMR spectroscopy, and the catenated nature of the small rings was confirmed using two-dimensional diffusion-ordered NMR spectroscopy

    Blur resolved OCT: full-range interferometric synthetic aperture microscopy through dispersion encoding

    Get PDF
    We present a computational method for full-range interferometric synthetic aperture microscopy (ISAM) under dispersion encoding. With this, one can effectively double the depth range of optical coherence tomography (OCT), whilst dramatically enhancing the spatial resolution away from the focal plane. To this end, we propose a model-based iterative reconstruction (MBIR) method, where ISAM is directly considered in an optimization approach, and we make the discovery that sparsity promoting regularization effectively recovers the full-range signal. Within this work, we adopt an optimal nonuniform discrete fast Fourier transform (NUFFT) implementation of ISAM, which is both fast and numerically stable throughout iterations. We validate our method with several complex samples, scanned with a commercial SD-OCT system with no hardware modification. With this, we both demonstrate full-range ISAM imaging, and significantly outperform combinations of existing methods.Comment: 17 pages, 7 figures. The images have been compressed for arxiv - please follow DOI for full resolutio

    Power Dependent Lineshape Corrections for Quantitative Spectroscopy

    Get PDF
    The Voigt profile - a convolution of a Gaussian and a Lorentzian - accurately describes the absorption lines of atomic and molecular gases at low probe powers. Fitting such to experimental spectra yields both the Lorentzian natural linewidth and the Gaussian Doppler broadening. However, as the probe power increases saturation effects introduce spurious power dependence into the fitted Doppler width. Using a simple atomic model, we calculate power-dependent corrections to the Voigt profile, which are parametrized by the Gaussian Doppler width, the Lorentzian natural linewidth, and the optical depth. We show numerically and experimentally that including the correction term substantially reduces the spurious power dependence in the fitted Gaussian width.Comment: 4 pages, 3 figure

    Dry Powder Deposition and Compaction for Functionally Graded Ceramics

    Full text link
    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65992/1/j.1551-2916.2006.01272.x.pd

    A Systemic Framework for Improving Clients\u27 Understanding of Software Requirements

    Get PDF
    This research proposes a systemic framework for the understanding of client requirements in Information System development that is particularly relevant for project contexts characterized by diversity of stakeholder values and significant complexity. In spite of the strong research tradition associated with Soft Systems Methodology and the growing interest in the Work System Method, the level of use of those by practitioners is not high as such situations require harnessing the strengths of more than one methodology. The paper explores the selection of techniques from three systems methodologies and mixing them to be applied in the process of requirements understanding by clients. The mixing of methods from various methodologies is justified through the principles of Critical Systems Practice and the process of their use is guided by Action Design Research. The contribution of the paper for the field of Information Systems is in the proposal of a more powerful framework for promoting organizational learning about software requirements understanding by clients

    Permittivity of Porous Titanate Dielectrics

    Full text link
    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65907/1/j.1551-2916.2006.01323.x.pd
    corecore