267 research outputs found
A Transportation Performance Measurement System with a Mississippi Case Study
In current literature and practices, there are no systematic and user-oriented intermodal transportation performance measures. After identifying customer needs and transportation goals, this paper proposes a set of system-level performance measures for intermodal transportation that are user-oriented, scalable, systematic, and scientific. The measures can be used to compare intermodal design alternatives or to evaluate existing transportation systems with any size and any mode. The highway system in Mississippi is analyzed as a case study. The case study demonstrates the existing data sources, the methods of calculating the measures, and the means of evaluating transportation systems with the measures
A Transportation Performance Measurement System with a Mississippi Case Study
In current literature and practices, there are no systematic and user-oriented intermodal transportation performance measures. After identifying customer needs and transportation goals, this paper proposes a set of system-level performance measures for intermodal transportation that are user-oriented, scalable, systematic, and scientific. The measures can be used to compare intermodal design alternatives or to evaluate existing transportation systems with any size and any mode. The highway system in Mississippi is analyzed as a case study. The case study demonstrates the existing data sources, the methods of calculating the measures, and the means of evaluating transportation systems with the measures
A Conceptual Framework for E-tailing Quality and Its Evaluation
The Internet’s influence in creating e-services has been revolutionary for retailer. Clearly, The Internet is fast becoming an important new channel for businesses in retailing, raising e-services as the emergent business paradigm in the industrialized world. Unfortunately, past research on measuring e-tailing quality is scarce. This paper provides a conceptual framework for e-tailing quality and discusses its evaluation. First, we summarize the main previous literature about service quality and e-service quality. Second, three analytical dimensions are identified: website quality, action quality and result quality, and each has its sub-dimensions. Each has different influence degree. Finally, we analyzing the evaluation way by comparing the online shoppers’ perceived and expectation e-service. Future recommendations are also offered
A Novel Neutral-Point Potential Balance Strategy for Three-Level NPC Back-to-Back Converter Based on the Neutral-Point Current Injection Model
The neutral-point (NP) potential balance control in three-level neutral-point-clamped (NPC) back-to-back converter is a research nodus. Its current strategies are the same as the strategies of a single three-level NPC converter. But the strategies do not give full play to its advantages that the neutral-point current can only flow through the connected midlines in both sides of the converter but does not flow through the DC-bus capacitors. In this paper, firstly the NP potential model based on the NP current injected is proposed. It overcomes numerous variable constraints and mutual coupling in the conventional model based on the zero-sequence voltage injected. And then on this basis, three NP-potential balance control algorithms, unilateral control, bilateral independent control, and bilateral coordinated control, are proposed according to difference requirements. All of these algorithms use the midlines rather than the DC-bus capacitors to flow the NP current as much as possible. Their control abilities are further quantitatively analyzed and compared. Finally, simulation results verify the validity and effectiveness of these algorithms
Modulation of the Work Function by the Atomic Structure of Strong Organic Electron Acceptors on H-Si(111)
Advances in hybrid organic/inorganic architectures for optoelectronics can be
achieved by understanding how the atomic and electronic degrees of freedom
cooperate or compete to yield the desired functional properties. Here we show
how work-function changes are modulated by the structure of the organic
components in model hybrid systems. We consider two cyano-quinodimethane
derivatives (F4-TCNQ and F6-TCNNQ), which are strong electron-acceptor
molecules, adsorbed on H-Si(111). From systematic structure searches employing
range-separated hybrid HSE06 functional including many body van der Waals
contributions, we predict that despite their similar composition, these
molecules adsorb with significantly different densely-packed geometries in the
first layer, due to strong intermolecular interaction. F6-TCNNQ shows a much
stronger intralayer interaction (primarily due to van der Waals contributions)
than F4-TCNQ in multilayered structures. The densely-packed geometries induce a
large interface-charge rearrangement that result in a work-function increase of
1.11 and 1.76 eV for F4-TCNQ and F6-TCNNQ, respectively. Nuclear fluctuations
at room temperature produce a wide distribution of work-function values, well
modeled by a normal distribution with {\sigma}=0.17 eV. We corroborate our
findings with experimental evidence of pronounced island formation for F6-TCNNQ
on H-Si(111) and with the agreement of trends between predicted and measured
work-function changes
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