6,090 research outputs found

    Averaging of the electron effective mass in multicomponent transparent conducting oxides

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    We find that layered materials composed of various oxides of cations with s2s^2 electronic configuration, XY2XY_2O4_4, XX=In or Sc, YY=Ga, Zn, Al, Cd and/or Mg, exhibit isotropic electron effective mass which can be obtained via averaging over those of the corresponding single-cation oxide constituents. This effect is due to a hybrid nature of the conduction band formed from the s-states of {\it all} cations and the oxygen p-states. Moreover, the observed insensitivity of the electron effective mass to the oxygen coordination and to the distortions in the cation-oxygen chains suggests that similar behavior can be expected in technologically important amorphous state. These findings significantly broaden the range of materials as efficient transparent conductor hosts.Comment: Figures with higher resolution include

    Unconventional approaches to combine optical transparency with electrical conductivity

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    Combination of electrical conductivity and optical transparency in the same material -- known to be a prerogative of only a few oxides of post-transition metals, such as In, Sn, Zn and Cd -- manifests itself in a distinctive band structure of the transparent conductor host. While the oxides of other elements with s2s^2 electronic configuration, for example, Mg, Ca, Sc and Al, also exhibit the desired optical and electronic features, they have not been considered as candidates for achieving good electrical conductivity because of the challenges of efficient carrier generation in these wide-bandgap materials. Here we demonstrate that alternative approaches to the problem not only allow attaining the transport and optical properties which compete with those in currently utilized transparent conducting oxides (TCO), but also significantly broaden the range of materials with a potential of being developed into novel functional transparent conductors.Comment: Accepted for publicatio

    On the microeconomic problems studied by portfolio theory

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    In the paper we consider economically motivated problems, which are treated with the help of methods of portfolio theory that goes back to the papers by H. Markowitz [1] and J. Tobin [2]. We show that the portfolio theory initially developed for risky securities (stocks) could be applied to other objects. In the present paper we consider several situations where such an application is reasonable and seems to be fruitful. Namely, we consider the problems of constructing the efficient portfolio of banking services and the portfolio of counteragents of a firm. © 2012 American Institute of Physics

    Demographic Transformation and the Future of Museums

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    In 2009 the Center for the Future of Museums commissioned Betty Farrell to produce a report to explore in more detail the demographic trends in American society and their implications for museums. The report identifies, synthesizes, and interprets existing research on demographics, cultural consumer attitudes, museum diversity practices, and related topics. It is meant to help the museum field explore the future of museums in a "majority minority" society. Topics of inquiry include national demographic projections for the next 25 years with a focus on the shifting racial and ethnic composition of the United States; current patterns of museum attendance (and cultural participation more generally) by race, ethnicity, cultural origin and other relevant factors; culturally/ethnically specific attitudes towards museums, including perceptual and behavioral barriers to museum attendance; ways that museums currently reach out to diverse audiences; specific models and best practices; and larger trends in societal attitudes towards racial and other classifications

    Work hardening behavior in a steel with multiple TRIP mechanisms

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    Transformation induced plasticity (TRIP) behavior was studied in steel with composition Fe-0.07C-2.85Si-15.3Mn-2.4Al-0.017N that exhibited two TRIP mechanisms. The initial microstructure consisted of both {\epsilon}- and {\alpha}-martensites with 27% retained austenite. TRIP behavior in the first 5% strain was predominately austenite transforming to {\epsilon}-martensite (Stage I), but upon saturation of Stage I, the {\epsilon}-martensite transformed to {\alpha}-martensite (Stage II). Alloy segregation also affected the TRIP behavior with alloy rich regions producing TRIP just prior to necking. This behavior was explained by first principle calculations that revealed aluminum significantly affected the stacking fault energy in Fe-Mn-Al-C steels by decreasing the unstable stacking fault energy and promoting easy nucleation of {\epsilon}-martensite. The addition of aluminum also raised the intrinsic stacking fault energy and caused the {\epsilon}-martensite to be unstable and transform to {\alpha}-martensite under further deformation. The two stage TRIP behavior produced a high strain hardening exponent of 1.4 and led to ultimate tensile strength of 1165 MPa and elongation to failure of 35%.Comment: submitted to Met. Mater. Trans. A manuscript E-TP-12-953-

    Assessment of Company Competitive Advantage Strategy Through Supply Chain

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    Abstract— The article discusses the methodological aspects of an enterprise competitiveness improvement based on the strategic development of supply chain management. In modern conditions, a high level of quality provision in enterprise activities is becoming an important factor forming a competitive advantage in the context of enterprise struggle increase both during the economic recovery and during the period of financial decline in various economic and political situations. The aim of the work is to justify the methodological aspects of the company competitive advantage strategy evaluation through the supply chain management. The study proposed an algorithm for a competitive advantage strategy selection using the example of a modern pulp and paper mill, developed the methodology for assessing the impact of strategic competitive abilities on company sustainable development, and identified strategic competitive advantages. Our model confirmed the relationship between supply chain management measures (strategic partnership with supplier, customer relationship management, informing level, informing quality and procrastination) and a competitive advantage’s component
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