Optimal Fair Scheduling in S-TDMA Sensor Networks for Monitoring River Plumes

Underwater wireless sensor networks (UWSNs) are a promising technology to provide oceanographers with environmental data in real time. Suitable network topologies to monitor estuaries are formed by strings coming together to a sink node.This network may be understood as an oriented graph. A number of MAC techniques can be used in UWSNs, but Spatial-TDMA is preferred for fixed networks. In this paper, a scheduling procedure to obtain the optimal fair frame is presented, under ideal conditions of synchronization and transmission errors. The main objective is to find the theoretical maximum throughput by overlapping the transmissions of the nodes while keeping a balanced received data rate from each sensor, regardless of its location in the network. The procedure searches for all cliques of the compatibility matrix of the network graph and solves a Multiple-Vector Bin Packing (MVBP) problem. This work addresses the optimization problem and provides analytical and numerical results for both the minimum frame length and the maximum achievable throughput

Optimal scheduling and fair servicepolicy for STDMA in underwater networks with acoustic communications

In this work, a multi-hop string network with a single sink node is analyzed. A periodic optimal scheduling for TDMA operation that considers the characteristic long propagation delay of the underwater acoustic channel is presented. This planning of transmissions is obtained with the help of a new geometrical method based on a 2D lattice in the space-time domain. In order to evaluate the performance of this optimal scheduling, two service policies have been compared: FIFO and Round-Robin. Simulation results, including achievable throughput, packet delay, and queue length, are shown. The network fairness has also been quantified with the Gini index

Grados de obturación alcanzados por emisores a lo largo de un tiempo trabajando con aguas residuales depuradas

Tanto el respeto al medio ambiente como la necesidad de buscar nuevos recursos hídricos está promoviendo la reutilización de aguas residuales utilizando sistemas de riego por goteo, garantizando con un buen manejo y aplicación un uso eficiente del recurso agua. Para conocer el principal problema que se plantea en estos sistemas, como es la obstrucción de los emisores, se ha llevado a cabo este trabajo. Se han estudiado los emisores que son más aptos para resistir al atascamiento, para ello se ha seguido la evolución a lo largo del tiempo de varios emisores comerciales trabajando con distintas calidades de aguas depuradas, calculando el grado de obturación (G.O) que alcanzan cada uno de ellos. Entre las conclusiones destacar que la calidad del agua residual influye muy significativamente en el grado de obturación, recomendándose para disminuir éste, al menos un tratamiento primario al agua residual más una filtración

Operación multihop eficiente en redes acústicas submarinas de sensores con planificación TDMA

Dos de los problemas a los que se enfrentan las comunicaciones inalámbricas submarinas, y que limitan sobremanera la velocidad de transmisión de los datos, son (i) la atenuación en el medio acuático, que es selectiva en frecuencia, y (ii) el alto retardo de propagación. El primer factor, obliga a usar frecuencias bajas (acústicas), con una consiguiente degradación en la velocidad de transmisión de datos, que limita las aplicaciones posibles. El segundo problema, hace que las técnicas empleadas para el acceso y transmisión de los nodos (capa de enlace OSI o MAC), deban ser lo más eficientes posible para no demorar en demasía la entrega de datos. En concreto, en esta comunicación abordamos el problema de una red de nodos con sensores que pretende ser diseñada para minimizar el impacto de los dos problemas anteriormente citados. Para ello, se establece una técnica TDMA en el acceso al medio y se estudia el efecto que tiene una disciplina de servicio para la capa MAC para transmitir paquetes, basada en una cola FIFO con prioridad, bajo una planificación eficiente de transmisiones en la red. Se plantean distintos escenarios de tráfico generado uniforme o no uniforme por los nodos sensores, además de introducir una métrica (índice de Gini) para la uniformidad de paquetes entregados al Gateway por cada nodo, que es un criterio para que la red sea justa (fairness). Como resultados, se aportan medidas de throughput, retardo extremo a extremo de los paquetes, así como tamaño medio y máximo de las colas de cada nodo.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Optimal Fair Scheduling in S-TDMA Sensor Networks for Monitoring River Plumes

Underwater wireless sensor networks (UWSNs) are a promising technology to provide oceanographers with environmental data in real time. Suitable network topologies to monitor estuaries are formed by strings coming together to a sink node. This network may be understood as an oriented graph. A number of MAC techniques can be used in UWSNs, but Spatial-TDMA is preferred for fixed networks. In this paper, a scheduling procedure to obtain the optimal fair frame is presented, under ideal conditions of synchronization and transmission errors. The main objective is to find the theoretical maximum throughput by overlapping the transmissions of the nodes while keeping a balanced received data rate from each sensor, regardless of its location in the network. The procedure searches for all cliques of the compatibility matrix of the network graph and solves a Multiple-Vector Bin Packing (MVBP) problem. This work addresses the optimization problem and provides analytical and numerical results for both the minimum frame length and the maximum achievable throughput

Planificación S-TDMA en redes submarinas de comunicaciones inalámbricas

Las redes submarinas de sensores son de importancia en la vigilancia y monitorización del medio submarino. Si se desea que las redes sean inalámbricas y con un alcance superior a unos pocos metros, las comunicaciones han de ser acústicas. El canal acústico submarino es de poca capacidad de transmisión y muy hostil en términos de ruido y desvanecimiento, ya que es selectivo en frecuencia. Además, estas redes inalámbricas plantean el problema añadido de la alimentación eléctrica. En redes de tráfico saturado, el procedimiento más eficiente de acceso al medio es TDMA espacial, por los menores “overheads” y la práctica ausencia de “handshaking”. En esta comunicación se presenta un procedimiento para la obtención de una planificación eficiente en redes submarinas de comunicaciones que utilicen TDMA espacial. El procedimiento está basado en dos algoritmos heurísticos encadenados y encuentra una planificación temporal eficiente para conseguir la misma cantidad de información de los sensores de cada nodo de la red.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Grados de obturación alcanzados por emisores a lo largo de un tiempo trabajando con aguas residuales depuradas

[ES] Tanto el respeto al medio ambiente como la necesidad de buscar nuevos recursos hídricos está promoviendo la reutilización de aguas residuales utilizando sistemas de riego por goteo, garantizando con un buen manejo y aplicación un uso eficiente del recurso agua. Para conocer el principal problema que se plantea en estos sistemas, como es la obstrucción de los emisores, se ha llevado a cabo este trabajo. Se han estudiado los emisores que son más aptos para resistir al atascamiento, para ello se ha seguido la evolución a lo largo del tiempo de varios emisores comerciales trabajando con distintas calidades de aguas depuradas, calculando el grado de obturación (G.O) que alcanzan cada uno de ellos. Entre las conclusiones destacar que la calidad del agua residual influye muy significativamente en el grado de obturación, recomendándose para disminuir éste, al menos un tratamiento primario al agua residual más una filtración.Chica Moreno, RM.; Roldán Cañas, J.; Alcaide García, M. (2001). 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Individual and environmental factors associated with death of cyclists involved in road crashes in Spain: a cohort study

Objective To quantify the magnitude of associations between cyclist fatalities and both cyclist and environment related characteristics in Spain during the first 24 hours after a crash. Results Non-use of a helmet was directly associated with death (IDR 1.43, 95% CI 1.25 to 1.64). Among other cyclist characteristics, age after the third decade of life was also directly associated with death, especially in older cyclists (‘over 74’ category, IDR 4.61, 95% CI 3.49 to 6.08). The association with death did not differ between work-related cycling and other reasons for cycling. There was an inverse association with death for crashes in urban areas and on community roads. Any adverse meteorological condition also showed a direct association with death, whereas altered road surfaces showed an inverse association. Crashes during nighttime were directly associated with death, with a peak between 3:00 and 5:59 am (IDR 1.58, 95% CI 1.03 to 2.41). Conclusions We found strong direct and inverse associations between several cyclist and environment related variables and death. These variables should be considered in efforts to prioritise public health measures aimed at reducing the number of cycling-related fatalities.This work was partially supported by the National Council of Science and Technology of Mexico [doctorate grant number 410668]

Nursing intervention to improve positive mental health and self-care skills in people with chronic physical health conditions

The exponential increase in the number of people suffering chronic illness has become a problem for which healthcare services need a response. The inclusion of self-care and positive mental health as part of a strategy to promote health offers an opportunity for a reorganization oriented towards community spaces and group interventions. This study undertook the assessment of an intervention designed to optimize the agency of and capacity for self-care and positive mental health by utilizing activities drawn from the Nursing Intervention Classification (NIC), specifically from Field 3 (Behavioral), and organized as a program called PIPsE. A quasi-experimental design was prepared with an intervention group (n = 22) and a control group (n = 22), in a primary care center in the Barcelona metropolitan area. The instruments used were two ad hoc questionnaires to collect sociodemographic and satisfaction information and two scales: the Appraisal of Self-care Agency Scale (ASA) and the Positive Mental Health Questionnaire (PMHQ). The results obtained showed a significant increase in self-care capacity and both overall positive mental health and mental health by factors in the intervention group

Effectiveness of the online 'Dialogue Circles' nursing intervention to increase positive mental health and reduce the burden of caregivers of patients with complex chronic conditions. Randomized clinical trial

The personal demands involved in caring for a chronically ill person can lead to emotional and physical exhaustion in caregivers. The aim of this study was to evaluate the effectiveness of an online nursing intervention called 'dialogue circles' designed to reduce caregiver overload and enhance positive mental health (PMH) in family caregivers. We used a pre-post design. The sample consisted of 86 family caregivers of patients with complex chronic conditions, randomly assigned to the intervention group (n = 43) or the control group (n = 43). All participants completed the Zarit scale and the Positive Mental Health Questionnaire 15 days before starting the intervention and 30 days after its completion. Comparison of the post-test changes revealed statistically significant differences between the two groups in PMH and overload, with the intervention group showing greater positive changes in all dimensions of PMH after the intervention and lower scores on overload. In conclusion, the results suggest that incorporating dialogue circles as an online nursing intervention in the caregivers of patients with complex chronic conditions can enhance PMH and decrease caregiver overload, especially in settings where face-to-face encounters are not possible