Resonance scattering of light by spherical photonic clusters: analytical approach

Scattering of light by the photonic clusters made of small particles is studied with the help of the quasiperiodicity condition and the local perturbation method. The analytical expression for the field scattered by the cluster is presented and the conditions of resonance scattering are found. The conditions of the zero scattering by the cluster are also found.Comment: 11 page

Context as foundation for a semantic desktop

Adoption of semantic web technologies and principles presents an opportunity to change the conceptual model of desktop computing. Moving from a traditional position where the desktop is largely tied to a specific computational device, a semantic desktop could exist as a broad, networked space defined relative to the user. In this position paper we argue that personal, computing, and knowledge contexts are the appropriate means by which to define and shape the desktop space, and that collectively they provide the foundation for novel functionality in a semantic desktop

Linkage by Generically Gorenstein Cohen-Macaulay Ideals.

In a Gorenstein local ring R, two ideals A and B are said to be linked by an ideal I if the two relations A = (I: B) and B = (I: A) hold. In the case that I is a complete intersection, or a Gorenstein ideal, it is known that linkage preserves the Cohen-Macaulay property. That is, if A is a Cohen-Macaulay ideal, then so is B. However, if I is allowed to be a generically Gorenstein, Cohen-Macaulay ideal, easy examples show that this type of linkage does not preserve the Cohen-Macaulay property. The primary purpose of this work is to investigate how much of the Cohen-Macaulay property this more general kind of linkage does preserve. By associating to I an auxiliary ideal J, for which J/I is isomorphic to the canonical module K\sb{R/I} of R/I, we are able to give complete conditions for various types of Cohen-Macaulay conditions that B possesses, when B is linked by I to a Cohen-Macaulay ideal A. In particular, we give a criterion for B to be a Cohen-Macaulay ideal, and when it is not, for R/B to have high depth. We also give a description in some cases of the non-Cohen-Macaulay locus of R/B, including a calculation of its dimension. In these cases, there is an interesting relationship between the depth of R/B and the dimension of the non-Cohen-Macaulay locus. Finally, we give some remarks on a construction of a free resolution of R/B from given resolutions

Validation of a Thermo-Ablative Model of Elastomeric Internal Insulation Materials

In thermo-ablative material modeling, as in many fields of analysis, the quality of the existing models significantly exceeds that of the experimental data required for their validation. In an effort to narrow this gap, a laboratory-scale internal insulation test bed was developed that exposes insulation samples to realistic solid rocket motor (SRM) internal environments while being instrumented to record real-time rates of both model inputs (i.e., chamber pressure, total surface heat flux, and radiative heat flux) as well as model outputs (i.e., material decomposition depths (MDDs) and in-depth material temperatures). In this work, the measured SRM internal environment parameters were used in conjunction with equilibrium thermochemistry codes as inputs to one-dimensional thermo-ablative models of the PBINBR and CFEPDM insulation samples used in the lab-scale test firings. The computed MDD histories were then compared with those deduced from real-time X-ray radiography of the insulation samples, and the calculated in-depth temperatures were compared with those measured by embedded thermocouples. The results of this exercise emphasize the challenges of modeling and testing elastomeric materials in SRM environments while illuminating the path forward to improved fidelity

Validation of a Solid Rocket Motor Internal Environment Model

In a prior effort, a thermal/fluid model of the interior of Penn State University's laboratory-scale Insulation Test Motor (ITM) was constructed to predict both the convective and radiative heat transfer to the interior walls of the ITM with a minimum of empiricism. These predictions were then compared to values of total and radiative heat flux measured in a previous series of ITM test firings to assess the capabilities and shortcomings of the chosen modeling approach. Though the calculated fluxes reasonably agreed with those measured during testing, this exercise revealed means of improving the fidelity of the model to, in the case of the thermal radiation, enable direct comparison of the measured and calculated fluxes and, for the total heat flux, compute a value indicative of the average measured condition. By replacing the P1-Approximation with the discrete ordinates (DO) model for the solution of the gray radiative transfer equation, the radiation intensity field in the optically thin region near the radiometer is accurately estimated, allowing the thermal radiation flux to be calculated on the heat-flux sensor itself, which was then compared directly to the measured values. Though the fully coupling the wall thermal response with the flow model was not attempted due to the excessive computational time required, a separate wall thermal response model was used to better estimate the average temperature of the graphite surfaces upstream of the heat flux gauges and improve the accuracy of both the total and radiative heat flux computations. The success of this modeling approach increases confidence in the ability of state-of-the-art thermal and fluid modeling to accurately predict SRM internal environments, offers corrections to older methods, and supplies a tool for further studies of the dynamics of SRM interiors

Tailoring Technical Services Data to Fit the Changing Needs of Academic Liaisons

Increasingly dynamic collections, changing curriculums, and tightening budgets work together to put more and more pressure on liaisons to stay well-informed and respond nimbly when confronting collection management decisions and opportunities. In many cases, data potentially useful to liaisons already exists within technical services units as a product of other library activities and functions. When approached from a collection management perspective, this data can often be repurposed to meet the information needs of academic liaisons and other collection managers as they attempt to meet the demands of evolving liaison roles and changing collection priorities. The presenters will discuss their efforts at the University of Kentucky Libraries to develop enhanced reporting instruments and procedures intended to employ technical services data to the greater benefit of academic liaisons

Arab Spring Book Exhibit Bibliography and Call Numbers

An exhibit of books about Arab Spring was held in the William T. Young Library from Oct. 2014 through Feb. 2015 in celebration of the Year of the Middle Year at the University of Kentucky. An annotated bibliography for the exhibit is available by clicking the Download button on the right. Click here to view the online guide about the book exhibit