Amorphous Placement and Retrieval of Sensory Data in Sparse Mobile Ad-Hoc Networks

Abstract—Personal communication devices are increasingly being equipped with sensors that are able to passively collect information from their surroundings – information that could be stored in fairly small local caches. We envision a system in which users of such devices use their collective sensing, storage, and communication resources to query the state of (possibly remote) neighborhoods. The goal of such a system is to achieve the highest query success ratio using the least communication overhead (power). We show that the use of Data Centric Storage (DCS), or directed placement, is a viable approach for achieving this goal, but only when the underlying network is well connected. Alternatively, we propose, amorphous placement, in which sensory samples are cached locally and informed exchanges of cached samples is used to diffuse the sensory data throughout the whole network. In handling queries, the local cache is searched first for potential answers. If unsuccessful, the query is forwarded to one or more direct neighbors for answers. This technique leverages node mobility and caching capabilities to avoid the multi-hop communication overhead of directed placement. Using a simplified mobility model, we provide analytical lower and upper bounds on the ability of amorphous placement to achieve uniform field coverage in one and two dimensions. We show that combining informed shuffling of cached samples upon an encounter between two nodes, with the querying of direct neighbors could lead to significant performance improvements. For instance, under realistic mobility models, our simulation experiments show that amorphous placement achieves 10% to 40% better query answering ratio at a 25% to 35% savings in consumed power over directed placement.National Science Foundation (CNS Cybertrust 0524477, CNS NeTS 0520166, CNS ITR 0205294, EIA RI 0202067

Amorphous Placement and Informed Diffusion for Timely Monitoring by Autonomous, Resource-Constrained, Mobile Sensors

Personal communication devices are increasingly equipped with sensors for passive monitoring of encounters and surroundings. We envision the emergence of services that enable a community of mobile users carrying such resource-limited devices to query such information at remote locations in the field in which they collectively roam. One approach to implement such a service is directed placement and retrieval (DPR), whereby readings/queries about a specific location are routed to a node responsible for that location. In a mobile, potentially sparse setting, where end-to-end paths are unavailable, DPR is not an attractive solution as it would require the use of delay-tolerant (flooding-based store-carry-forward) routing of both readings and queries, which is inappropriate for applications with data freshness constraints, and which is incompatible with stringent device power/memory constraints. Alternatively, we propose the use of amorphous placement and retrieval (APR), in which routing and field monitoring are integrated through the use of a cache management scheme coupled with an informed exchange of cached samples to diffuse sensory data throughout the network, in such a way that a query answer is likely to be found close to the query origin. We argue that knowledge of the distribution of query targets could be used effectively by an informed cache management policy to maximize the utility of collective storage of all devices. Using a simple analytical model, we show that the use of informed cache management is particularly important when the mobility model results in a non-uniform distribution of users over the field. We present results from extensive simulations which show that in sparsely-connected networks, APR is more cost-effective than DPR, that it provides extra resilience to node failure and packet losses, and that its use of informed cache management yields superior performance

Customer Perception of Drive-Thru Service

The rapid growth of off-premise dining and, consequently, drive- thru service, presents the challenge of building customer loyalty in a highly competitive marketplace. In this study, customer perceptions of drive-thru service associated with quick service restaurants were examined. Results suggest that service time appears to differ among quick service restaurants, even those within the same chain. Employee courtesy was rated positively at all restaurants, as was food quality. The implications of these results for restaurateurs who offer drive-thru service are discussed

Impuesto al valor agregado

A lo largo de su historia, la Argentina se ha caracterizado por ser un país exportador debido a la excelente calidad de sus materias primas y a la gran diversidad de sus productos. Después de la crisis del año 2001 se implementó un tipo de cambio favorable a los consumidores del exterior, lo que potenció los beneficios de dedicarse a la exportación. En la actualidad, hay muchos emprendedores y pequeñas y medianas empresas que operan en el comercio internacional o quieren comenzar a hacerlo, pero ellos no conocen en su totalidad cuáles son las implicancias inherentes a las importaciones y exportaciones que pueden tener en su actividad, como por ejemplo en el IVA. De acuerdo a consultas efectuadas en esta clase de empresas, la mayoría de ellas se plantea los siguientes interrogantes: ¿Cuál es la normativa actual que rige a las importaciones y exportaciones? ¿Se encuentran gravadas por el Impuesto al Valor Agregado? ¿Cuáles son las ventajas que brinda la legislación vigente? ¿Existe la posibilidad de recuperar los impuestos abonados en el mercado interno? ¿De qué forma puede lograrlo? ¿Qué régimen legal se aplica? ¿Qué tipos de recaudos deben tomarse para evitar inconvenientes ante los distintos organismos? En el presente trabajo nos proponemos brindar las herramientas necesarias para que este tipo de empresarios puedan tener un preciso conocimiento sobre los efectos del IVA en las importaciones y exportaciones y se encuentren en condiciones concretas de recuperar el crédito fiscal vinculado a operaciones de exportación.Fil: Becker, Sebastián Leonardo. Universidad Nacional de Cuyo. Facultad de Ciencias Económicas.Fil: Bertona Morcos, Valentina. Universidad Nacional de Cuyo. Facultad de Ciencias Económicas.Fil: Wiederhold, Kevin. Universidad Nacional de Cuyo. Facultad de Ciencias Económicas