Model Selection Approach for Distributed Fault Detection in Wireless Sensor Networks

Sensor networks aim at monitoring their surroundings for event detection and object tracking. But, due to failure, or death of sensors, false signal can be transmitted. In this paper, we consider the problems of distributed fault detection in wireless sensor network (WSN). In particular, we consider how to take decision regarding fault detection in a noisy environment as a result of false detection or false response of event by some sensors, where the sensors are placed at the center of regular hexagons and the event can occur at only one hexagon. We propose fault detection schemes that explicitly introduce the error probabilities into the optimal event detection process. We introduce two types of detection probabilities, one for the center node, where the event occurs and the other one for the adjacent nodes. This second type of detection probability is new in sensor network literature. We develop schemes under the model selection procedure, multiple model selection procedure and use the concept of Bayesian model averaging to identify a set of likely fault sensors and obtain an average predictive error.Comment: 14 page

A Technique to Minimize Contention in Optical Burst Switching Networks

Optical burst switching (OBS) is the new switching technique for next generation optical networks. However, there are certain issues such as burst aggregation, scheduling, contention resolution and QoS that needs to be addressed in OBS. This thesis is an attempt to address the burst scheduling and burst contention in OBS networks. Several scheduling algorithms have been proposed in the literature, which can be categorized into Horizon and Void lling scheduling algorithm. Void lling algorithms perform better because they exploits void within a channel for scheduling. Reported void lling algorithms - Latest available unscheduled channel with void lling (LAUC-VF) and Minimum end void (Min-EV) - do not consider the void duration in scheduling. In this thesis we propose a new scheduling algorithm called Best Fit Void Filling (BFVF), which consider both void duration and incoming burst length to nd an optimal void channel. We simulate our proposed scheme using obs-ns simulator and compared with LAUC-VF and Min-EV algorithm. Result shows that the burst loss ratio is lower and channel utilization is higher in our proposed scheme

Bounds on the Size of the Minimum Dominating Sets of Some Cylindrical Grid Graphs

Let γPm □ Cn denote the domination number of the cylindrical grid graph formed by the Cartesian product of the graphs Pm, the path of length m, m≥2, and the graph Cn, the cycle of length n, n≥3. In this paper we propose methods to find the domination numbers of graphs of the form Pm □ Cn with n≥3 and m=5 and propose tight bounds on domination numbers of the graphs P6 □ Cn, n≥3. Moreover, we provide rough bounds on domination numbers of the graphs Pm □ Cn, n≥3 and m≥7. We also point out how domination numbers and minimum dominating sets are useful for wireless sensor networks.</jats:p

Packing Problem and Random Coverage in Continuous Domain

The packing problem is a well known-problem. There are several versions of this problem. In this paper we consider packing or covering of a disc of a given radius r by a number of discs of unit radius. We introduced two types of packing, hexagonal packing and square packing. We show that hexagonal packing is better in the sense that it needs less discs to cover a disc of higher radius. Coverage problem is similar to the packing problem in continuous domain. Coverage is essential in wireless sensor networks. In this paper we also discuss the coverage problem in random deployment scenario

Failure to thrive and nephrocalcinosis due to distal renal tubular acidosis: A rare presentation of pediatric lupus nephritis

A 9-year-old female child was initially diagnosed of having nephrocalcinosis with distal renal tubular acidosis (dRTA) while investigating for short stature. She later on developed features of nephrotic syndrome (NS) while on treatment for RTA. Investigation for the cause of NS revealed very strong serological evidence in favor of systemic lupus erythematosus (SLE). Histopathological confirmation could not be done due to bilateral severely contracted kidneys. There are a few case reports of dRTA as the presentation of SLE, but nephrocalcinosis with dRTA with subsequent manifestation of SLE has hitherto not been reported in literature