Efficient resonance computations for Helmholtz problems based on a Dirichlet-to-Neumann map

We present an efficient procedure for computing resonances and resonant modes of Helmholtz problems posed in exterior domains. The problem is formulated as a nonlinear eigenvalue problem (NEP), where the nonlinearity arises from the use of a Dirichlet-to-Neumann map, which accounts for modeling unbounded domains. We consider a variational formulation and show that the spectrum consists of isolated eigenvalues of finite multiplicity that only can accumulate at infinity. The proposed method is based on a high order finite element discretization combined with a specialization of the Tensor Infinite Arnoldi method. Using Toeplitz matrices, we show how to specialize this method to our specific structure. In particular we introduce a pole cancellation technique in order to increase the radius of convergence for computation of eigenvalues that lie close to the poles of the matrix-valued function. The solution scheme can be applied to multiple resonators with a varying refractive index that is not necessarily piecewise constant. We present two test cases to show stability, performance and numerical accuracy of the method. In particular the use of a high order finite element discretization together with TIAR results in an efficient and reliable method to compute resonances

Cuatro poemas en español de Opal Palmer Adisa

Opal Palmer Adisa (Kingston, 1953) es autora de varios libros de poesía y cuentos para niños y adultos. Entre sus trabajos más destacados se encuentra Pina, The Many-Eyed Fruit (1985), Bake-Face and Other Guava Stories (1986), Traveling Women (1989) y Tamarind and Mango Women (1992). Su trabajo ha sido ampliamente antologado en Norteamérica, el Caribe y Europa. Actualmente se desempeña como profesora de Literatura y Escritura creativa en el California College of the Arts. Su poética examina la identidad a través de múltiples lentes, pero siempre con el fin de desnudar y renombrar el ser. Para más información sobre la autora, visite su sitio web: www.opalpalmeradisa.comLos siguientes cuatro poemas son tomados de la revista Anthurium: A Caribbean Studies Journal, 6 (2), 2008, otoño

Castell: a heterogeneous cmp architecture scalable to hundreds of processors

Technology improvements and power constrains have taken multicore architectures to dominate microprocessor designs over uniprocessors. At the same time, accelerator based architectures have shown that heterogeneous multicores are very efficient and can provide high throughput for parallel applications, but with a high-programming effort. We propose Castell a scalable chip multiprocessor architecture that can be programmed as uniprocessors, and provides the high throughput of accelerator-based architectures. Castell relies on task-based programming models that simplify software development. These models use a runtime system that dynamically finds, schedules, and adds hardware-specific features to parallel tasks. One of these features is DMA transfers to overlap computation and data movement, which is known as double buffering. This feature allows applications on Castell to tolerate large memory latencies and lets us design the memory system focusing on memory bandwidth. In addition to provide programmability and the design of the memory system, we have used a hierarchical NoC and added a synchronization module. The NoC design distributes memory traffic efficiently to allow the architecture to scale. The synchronization module is a consequence of the large performance degradation of application for large synchronization latencies. Castell is mainly an architecture framework that enables the definition of domain-specific implementations, fine-tuned to a particular problem or application. So far, Castell has been successfully used to propose heterogeneous multicore architectures for scientific kernels, video decoding (using H.264), and protein sequence alignment (using Smith-Waterman and clustalW). It has also been used to explore a number of architecture optimizations such as enhanced DMA controllers, and architecture support for task-based programming models. ii

Evaluación de la distribución comercial de Colanta en la ciudad de Cartagena, frente a las empresas competidoras del sector

En la actualidad todas las empresas están en una búsqueda constante para lograr ser mejor, a través de la innovación y la tecnología. Es por ello que este trabajo ha tenido preferencia de investigación a una empresa de lácteos que ha estado en la búsqueda constante de innovación, y que es a su vez un estudio de caso atractivo para estudiar y comparar con las demás empresas de lácteos del sector. COLANTA es una empresa muy competida en la ciudad de Cartagena esto fue algo que me motivó para realizar el estudio, principalmente en el área de distribución para poder identificar los diferentes canales de distribución dentro de la empresa y dentro de cada una de las empresas competidoras de COLANTA como lo son ALPINA, ALQUERIA, ALGARRA, CODEGAN, COOLECHERA, entre otras que mencionaré más adelante en el estudio. Para el estudio se tendrá en cuenta todos aquellos procesos que ayuden a ser de la investigación un trabajo interesante que conlleve a la mejora continua especialmente en la parte de distribución en la empresa de lácteos en la ciudad de Cartagena. El estudio ha segmentado a la empresa en Cartagena ya que es una de las ciudades más importante donde hace presencia COLANTA, debido a que la empresa a estudiar se encuentra en varias ciudades y regiones de Colombia y sólo interesa es el comportamiento de la empresa en la ciudad presente, por tiempos, recursos etc.Incluye bibliografí

El negro en Colombia: posición social y relación con su ambiente socioeconómico en las novelas Chambacú corral de negro y Socavón

The following doctoral thesis explores the historical and literary context in the novels Chambacú, Black Slum, Manuel Zapata Olivella and Socavón, Helcias Martan Gongora. The document is presented as an analysis of the novels based on historical events in Colombian History. The close up to the novels must be understood starting in the literary Boom in Latin America until the postmodern literature. That will give the reader the appropriate tools to interpret the different folklorik representations such as poems, songs and legends found in the two novels that are studied in the text. It is relevant to denote that both novels point to the reconstruction of the diaspora in the History and daily life of Afro-colombian societies.Includes bibliographical references