True North: songs of the Arctic

This work consists of a 4-movement piece for orchestra, commissioned by the New Jersey Youth Symphony. The music is inspired by an expeditionary residency to the high arctic region of Svalbard led by The Arctic Circle organization. It is an effort to allow connections to grow between musicians and a rapidly disappearing part of our natural world. The music also serves an educational purpose by introducing extended techniques young musicians in a clear, playable and easy to execute manner

BCFT and OSFT moduli: an exact perturbative comparison

Starting from the pseudo-${\cal B}_0$ gauge solution for marginal deformations in OSFT, we analytically compute the relation between the perturbative deformation parameter $\tilde\lambda$ in the solution and the BCFT marginal parameter $\lambda$, up to fifth order, by evaluating the Ellwood invariants. We observe that the microscopic reason why $\tilde\lambda$ and $\lambda$ are different is that the OSFT propagator renormalizes contact term divergences differently from the contour deformation used in BCFTComment: 26+5 pages, 10 figures V2: minor improvements, published versio

Topological Performance Measures as Surrogates for Physical Flow Models for Risk and Vulnerability Analysis for Electric Power Systems

Critical infrastructure systems must be both robust and resilient in order to ensure the functioning of society. To improve the performance of such systems, we often use risk and vulnerability analysis to find and address system weaknesses. A critical component of such analyses is the ability to accurately determine the negative consequences of various types of failures in the system. Numerous mathematical and simulation models exist which can be used to this end. However, there are relatively few studies comparing the implications of using different modeling approaches in the context of comprehensive risk analysis of critical infrastructures. Thus in this paper, we suggest a classification of these models, which span from simple topologically-oriented models to advanced physical flow-based models. Here, we focus on electric power systems and present a study aimed at understanding the tradeoffs between simplicity and fidelity in models used in the context of risk analysis. Specifically, the purpose of this paper is to compare performances measures achieved with a spectrum of approaches typically used for risk and vulnerability analysis of electric power systems and evaluate if more simplified topological measures can be combined using statistical methods to be used as a surrogate for physical flow models. The results of our work provide guidance as to appropriate models or combination of models to use when analyzing large-scale critical infrastructure systems, where simulation times quickly become insurmountable when using more advanced models, severely limiting the extent of analyses that can be performed

An evaluation of hospitality recruiters' perceptions of recruiting events [abstract]

Abstract only availableFaculty Mentor: Dr. James Groves, Hotel & Restaurant ManagementTraditionally, many hospitality companies have recruited college students by attending career days on campus and through interviews scheduled with hospitality career centers. The accepted model of recruiting and interviewing students was to first contact the student on campus, hold an initial interview, and invite the most qualified candidates to a company location for further interviews. However, during the 1990s, hospitality companies began reevaluating the necessity of this recruiting strategy. The apparent result of this change has been a diminished presence of companies physically coming to campus to recruit students. The purpose of this research was to obtain the perception of recruiters who regularly come to the MU campus as to their perceptions of current recruiting methods. Recruiters were specifically asked their perceptions concerning types of events they had recruited in the past, their preference as to type of event, and expected results (students hired) from these events. Results will indicate the best types of events for programs to host to attract recruiters to Hotel and Restaurant students. Results are expected to be useful for Hotel and Restaurant Management programs and for career services offices

Grotta della monaca (Calabria, Italia Meridionale). Una miniera neolitica per l'estrazione dell'ocra

Grotta della Monaca è una cavità carsica situata in Calabria (Italia meridionale). Ricerche archeologiche condotte sin dall’anno 2000, tuttora in corso, hanno permesso di riconoscere al suo interno le tracce di un’intensa attività estrattiva neolitica diretta allo sfruttamento di idrossidi di ferro (goethite e lepidocrocite), di cui la cavità è ricca. Le datazioni radiocarboniche inquadrano le coltivazioni minerarie tra V e IV millennio a.C. L’eccellente stato di conservazione delle testimonianze permette una sorprendente ricostruzione delle antiche strategie di acquisizione delle risorse minerarie ferrose

A Generalised RBF Finite Difference Approach to Solve Nonlinear Heat Conduction Problems on Unstructured Datasets

Radial Basis Functions have traditionally been used to provide a continuous interpolation of scattered data sets. However, this interpolation also allows for the reconstruction of partial derivatives throughout the solution field, which can then be used to drive the solution of a partial differential equation. Since the interpolation takes place on a scattered dataset with no local connectivity, the solution is essentially meshless. RBF-based methods have been successfully used to solve a wide variety of PDEs in this fashion. Such full-domain RBF methods are highly flexible and can exhibit spectral convergence rates Madych & Nelson (1990). However, in their traditional implementation the fully-populated matrix systems which are produced lead to computational complexities of at least order-N2 with datasets of size N. In addition, they suffer fromincreasingly poor numerical conditioning as the size of the dataset grows, and also with increasingly flat interpolating functions. This is a consequence of ill-conditioning in the determination of RBF weighting coefficients (as demonstrated in Driscoll & Fornberg (2002)), and is described by Robert Schaback Schaback (1995) as the uncertainty relation; better conditioning is associated with worse accuracy, and worse conditioning is associated with improved accuracy. Many techniques have been developed to reduce the effect of the uncertainty relation in the traditional RBF formulation, such as RBF-specific preconditioners Baxter (2002); Beatson et al. (1999); Brown (2005); Ling & Kansa (2005), or adaptive selection of data centres Ling et al. (2006); Ling & Schaback (2004). However, at present the only reliable methods of controlling numerical ill-conditioning and computational cost as problem size increases are domain decomposition Hernandez Rosales & Power (2007); Wong et al. (1999); Zhang (2007); Zhou et al. (2003), or the use of locally supported basis functions Fasshauer (1999); Schaback (1997); Wendland (1995); Wu (1995). In this work the domain decomposition principle is applied, forming a large number of heavily overlapping systems that cover the solution domain. A small RBF collocation system is formed around each global data centre, with each collocation system used to approximate the governing PDE at its centrepoint, in terms of the solution value at surrounding collocation points. This leads to a sparse global linear system which may be solved using a variety of standard solvers. In this way, the proposed formulation emulates a finite difference method, with the RBF collocation systems replacing the polynomial interpolation functions used in traditional finite difference methods. However, unlike such polynomial functions RBF collocation is well suited to scattered data, and the method may be applied to both structured and unstructured datasets without modification. The method is applied here to solve the nonlinear heat conduction equation. In order to reduce the nonlinearity in the governing equation the Kirchhoff integral transformation is applied, and the transformed equation is solved using a Picard iterative process. The application of the Kirchhoff transform necessitates that the thermal property functions be transformed to Kirchhoff space also. If the thermal properties are a known and integrable function of temperature then the transformation may be performed analytically. Otherwise, an integration-interpolation procedure can be performed using 1D radial basis functions, as described in Stevens & Power (2010). In recent years a number of local RBF collocation techniques have been proposed, and applied a wide variety of problems (for example; Divo & Kassab (2007); Lee et al. (2003); Sarler & Vertnik (2006); Wright & Fornberg (2006)). A more comprehensive review of such methods is given in Stevens et al. (2009). Unlike most local RBF collocation methods that are used in the literature, the technique described here utilises the Hermitian RBF collocation formulation (see section 2 for more details), and allows both the PDE-boundary and PDE-governing operators to be included within in the local collocation systems. This inclusion of the governing PDE within the basis functions is shown in Stevens et al. (2009) to significantly improve the accuracy and stability of solutions obtained for linear transport problems. Additionally, the incorporation of information about the convective velocity field into the basis functionswas shown to have a stabilising effect, similar to traditional upwinding methods but without the requirement to alter the stencil configuration based on the local convective field. The standard approach to the solution of linear and nonlinear heat conduction problems is the use of finite difference and finite volume methods with simple polynomial interpolants Bejan (1993); Holman (2002); Kreith & Bohn (2000). Due to the dominance of diffusion in most cases, central differencing techniques are commonly used to compute the heat fluxes. However, limiter methods (such as the unconditionally stable TVD schemes) may be used for nonlinear heat conduction problems where the effective convection term, which results from the non-zero variation of thermal conductivity with temperature, can be expected to approach the magnitude of the diffusive term (see, for example, Shen & Han (2002)). Full-domain RBF methods have also been examined for use with nonlinear heat conduction problems (see Chantasiriwan (2007)), however such methods are restricted to small dataset sizes, due to the computational cost and numerical conditioning experienced by full-domain RBF techniques on large datasets. The present work demonstrates how local RBF collocation may be used as an alternative to traditional finite difference and finite volume methods, for nonlinear heat conduction problems. The described method retains freedom from a volumetric mesh, while allowing solution over unstructured datasets. A central stencil configuration is used in each case, and the solution is stabilised via the inclusion of the governing and boundary PDEs within the local collocation systems (\u201cimplicit upwinding\u201d), rather than by adjusting the stencil configuration based on the local solution field (\u201ctraditional upwinding\u201d). The method is validated using a transient numerical example with a known analytical solution (see section 4), and the ability of the formulation to handle strongly nonlinear problems is demonstrated in the solution of a food freezing problem (see section 5)

L.V. Pumpjanskij (1891-1940) teorico della letteratura

Questa dissertazione ha lo scopo di presentare il contributo offerto da Lev Vasil'evič Pumpjanskij alla storia delle idee e della critica letteraria russa fra le due guerre attraverso una generale organizzazione e sistematizzazione del suo pensiero, molto spesso espresso in modo frammentario e criptico. Tale sistematizzazione ha seguito una linea interpretativa che, a nostro avviso, è fondamentale per la concezione di storia della letteratura russa elaborata dal critico: l'opposizione fra ciò che Pumpjanskij definisce «simbolo» e la sua «relativizzazione». È attraverso questa linea che tenteremo di organizzare l'idea di Pumpjanskij di storia della letteratura russa. Laddove la struttura concettuale presentata dallo studioso ci sembrerà frammentaria e asistematica cercheremo di integrarla, spiegarla e ricostruirla privilegiando un approccio filologico, storico e archivistico