Chittaranjan A. Mandal

Automatic detection of human fall in video

In this paper, we present an approach for human fall detection, which has important applications in the field of safety and security. The proposed approach consists of two parts: object detection and the use of a fall model. We use an adaptive background subtraction method to detect a moving object and mark it with its minimum-bounding box. The fall model uses a set of extracted features to analyze, detect and confirm a fall. We implement a two-state finite state machine (FSM) to continuously monitor people and their activities. Experimental results show that our method can detect most of the possible types of single human falls quite accurately.

Minimum Connected Dominating Set Using a Collaborative Cover Heuristic for Ad Hoc Sensor Networks

A minimum connected dominating set (MCDS) is used as virtual backbone for efficient routing and broadcasting in ad hoc sensor networks. The minimum CDS problem is NP-complete even in unit disk graphs. Many heuristics-based distributed approximation algorithms for MCDS problems are reported and the best known performance ratio has (4.8 + 1n 5). We propose a new heuristic called collaborative cover using two principles: 1) domatic number of a connected graph is at least two and 2) optimal substructure defined as subset of independent dominator preferably with a common connector. We obtain a partial Steiner tree during the construction of the independent set (dominators). A final postprocessing step identifies the Steiner nodes in the formation of Steiner tree for the independent set of G. We show that our collaborative cover heuristics are better than degree-based heuristics in identifying independent set and Steiner tree. While our distributed approximation CDS algorithm achieves the performance ratio of (4.8 + 1n 5) opt + 1.2, where opt is the size of any optimal CDS, we also show that the collaborative cover heuristic is able to give a marginally better bound when the distribution of sensor nodes is uniform permitting identification of the optimal substructures. We show that the message complexity of our algorithm is O(n¿2), ¿ being the maximum degree of a node in graph and the time complexity is O(n).

Rotation of CDS via Connected Domatic Partition in Ad Hoc Sensor Networks

Wireless ad hoc and sensor networks (WSNs) often require a connected dominating set (CDS) as the underlying virtual backbone for efficient routing. Nodes in a CDS have extra computation and communication load for their role as dominator, subjecting them to an early exhaustion of their battery. A simple mechanism to address this problem is to switch from one CDS to another fresh CDS, rotating the active CDS through a disjoint set of CDSs. This gives rise to the connected domatic partition (CDP) problem, which essentially involves partitioning the nodes V(G) of a graph G into node disjoint CDSs. We have developed a distributed algorithm for constructing the CDP using our maximal independent set (MlS)-based proximity heuristics, which depends only on connectivity information and does not rely on geographic or geometric information. We show that the size of a CDP that is identified by our algorithm is at least [delta+1/beta(c+1)] - f, where delta is the minimum node degree of G, beta les 2, c les 11 is a constant for a unit disk graph (UDG), and the expected value of f is epsidelta|V|, where epsi Lt 1 is a positive constant, and delta ges 48. Results of varied testing of our algorithm are positive even for a network of a large number of sensor nodes. Our scheme also performs better than other related techniques such as the ID-based scheme.

Ant-aggregation: ant colony algorithm for optimal data aggregation in wireless sensor networks

Data aggregation is an essential paradigm for energy efficient routing in energy constraint wireless sensor networks. The complexity of optimal data aggregation is NP-hard. Ant colony system, a population-based algorithm, provides natural and intrinsic way of exploration of search space in optimization settings in determining optimal data aggregation. The simulation results shows improvement in energy efficiency depending on the number of source nodes in the sensor network which is 45% energy efficiency using optimal aggregation compared to approximate aggregation schemes in moderate number of source whereas 20% energy efficiency in large number of source nodes. The proposed ant-aggregation algorithm is simulated in MATLAB

GABIND: a GA approach to allocation and binding for the high-level synthesis of data paths

We present here a technique for allocation and binding for data path synthesis (DPS) using a Genetic Algorithm (GA) approach. This GA uses an unconventional crossover mechanism relying on a force directed data path binding completion algorithm. The data path is synthesized using some supplied design parameters. A bus-based interconnection scheme, use of multi-port memories, and provision for multicycling and pipelining are the main features of this system. The method presented here has been applied to standard benchmark examples and the results obtained are promising.

An Equivalence-Checking Method for Scheduling Verification in High-Level Synthesis

A formal method for checking equivalence between a given behavioral specification prior to scheduling and the one produced by the scheduler is described. Finite state machine with data path (FSMD) models have been used to represent both the behaviors. The method consists of introducing cutpoints in one FSMD, visualizing its computations as concatenation of paths from cutpoints to cutpoints, and identifying equivalent finite path segments in the other FSMD; the process is then repeated with the FSMDs interchanged. Unlike many other reported techniques, this method is strong enough to work when path segments in the original behavior are merged, a common feature of scheduling. It is also capable of verifying several arithmetic transformations and many code-motion techniques employed during scheduling. Correctness and complexity of the method have been dealt with. Experimental results for several high-level synthesis benchmarks demonstrate the effectiveness of the method.

A Formal Verification Method of Scheduling in High-level Synthesis

This paper describes a formal method for checking the equivalence between the finite state machine with datapath (FSMD) model of the high-level behavioural specification and the FSMD model of the behaviour transformed by the scheduler. The method consists in introducing cutpoints in one FSMD, visualizing its computations as concatenation of paths from cutpoints to cutpoints and finally, identifying equivalent finite path segments in the other FSMD; the process is then repeated with the FSMDs interchanged. The method is strong enough to accommodate merging of the segments in the original behaviour by the typical scheduler such as DLS, a feature very common in scheduling but not captured by many works reported in the literature. It also handles arithmetic transformations

Formal verification of code motion techniques using data-flow-driven equivalence checking

A formal verification method for checking correctness of code motion techniques is presented in this article. Finite State Machine with Datapath (FSMD) models have been used to represent the input and the output behaviors of each synthesis step. The method introduces cutpoints in one FSMD, visualizes its computations as concatenation of paths from cutpoints to cutpoints, and then identifies equivalent finite path segments in the other FSMD; the process is then repeated with the FSMDs interchanged. Unlike many other reported techniques, the method is capable of verifying both uniform and nonuniform code motion techniques. It has been underlined in this work that for nonuniform code motions, identifying equivalent path segments involves model checking of some data-flow properties. Our method automatically identifies the situations where such properties are needed to be checked during equivalence checking, generates the appropriate properties, and invokes the model checking tool NuSMV to verify them. The correctness and the complexity of the method have been dealt with. Experimental results demonstrate the effectiveness of the method.

Verification of Code Motion Techniques Using Value Propagation

An equivalence checking method of finite state machines with datapath based on value propagation over model paths is presented here for validation of code motion transformations commonly applied during the scheduling phase of high-level synthesis. Unlike many other reported techniques, the method is able to handle code motions across loop bodies. It consists in propagating the variable values over a path to the subsequent paths on discovery of mismatch in the values for some live variable, until the values match or the final path segments are accounted for without finding a match. Checking loop invariance of the values being propagated beyond the loops has been identified to play an important role. Along with uniform and nonuniform code motions, the method is capable of handling control structure modifications as well. The complexity analysis depicts identical worst case performance as that of a related earlier method of path extension which fails to handle code motion across loops. The method has been implemented and satisfactorily tested on the outputs of a basic block-based scheduler, a path-based scheduler, and the high-level synthesis tool SPARK for some benchmark examples.

Complexity of fragmentable object bin packing and an application

Abstract We examine in this paper a variant of the bin packing problem, where it is permissible to fragment the objects while packing them into bins of fixed capacity. We call this the Fragmentable Object Bin Packing problem (FOBP). Fragmentation is associated with a cost, leading to the consumption of additional bin capacity. We show that the problem and its absolute approximation are both NP-complete. This is an interesting problem because if the cost of fragmentation is nullified then the problem can be easily solved optimally. If fragmentation is not permitted, then we get the usual bin packing problem. The application comes from a problem in data path synthesis where it is some times necessary to schedule data transfers, subject to restrictions arising from the underlying hardware. We show that FOBP reduces to a simplified version of this problem, thereby proving that it is also a similar hard problem.