The Hybrid method of parallelization (using MPI for internode communication and OpenMP for intra-node communication) seems a natural fit for the way most clusters are built today. It is generally expected to help programs run faster due to factors like availability of greater bandwidth for intra-node communication. However, optimizing hybrid applications for maximum speedup is difficult primari...

The need to debug hybrid parallel programs on heterogeneous accelerator clusters opens a new set of challenges for concurrently managing the processes and threads at node and accelerator levels. Currently, there exist open source debuggers for traditional HPC clusters, which support debugging of multi-node parallel programs. At present, debugging at the accelerator level is handled through lang...

With the computing industry trending towards multi-core processors, we study how a standard visualization algorithm, ray-casting volume rendering, can benefit from a hybrid parallelism approach. Hybrid parallelism provides the best of both worlds: using distributed-memory parallelism on a large numbers of cores increases available FLOPs and memory, and exploiting the shared memory parallelism a...

Epidemic spreading phenomena are ubiquitous in nature and society. Examples include the spreading of diseases, information, and computer viruses. Epidemics can spread by local spreading, where infected nodes can only infect a limited set of direct target nodes and global spreading, where an infected node can infect every other node. In reality, many epidemics spread using a hybrid mixture of bo...

Location services are used in mobile ad hoc and hybrid networks either to locate the geographic position of a given node in the network or for locating a data item (content). One of the main usages of position location services is in location based routing algorithms. In particular, geographic routing protocols can route messages more efficiently to their destinations based on the destination n...

An ad-hoc sensor network (ASN) is a group of sensing nodes that transmit data over wireless link to target node, direct or indirect, through series nodes. ASN becomes high-risk for several security exploits due the node’s limited resources. Internal threats are more challenging protect against than external attacks. The grouped, and calculate each trust level. level result combining internal de...

We consider distributed algorithms for data aggregation and function computation in sensor networks. The algorithms perform pairwise computations along edges of an underlying communication graph. A token is associated with each sensor node, which acts as a transmission permit. Nodes with active tokens have transmission permits; they generate messages at a constant rate and send each message to ...

This paper deals with two-processor scheduling for a class of program nets, that are acyclic and SWITCH-less, and of which each node has unity node firing time. Firstly, we introduce a hybrid priority list L∗ that generates optimal schedules for the nets whose AND-nodes possess at most single input edge. Then we extend L∗ to suit for general program nets to give a new priority list L∗∗. Finally...

We present the application of Genetic Programming (GP) in Branch and Bound (B&B) based Mixed Integer Linear Programming (MIP). The hybrid architecture introduced employs GP as a node selection expression generator: a GP run, embedded into the B&B process, exploits the characteristics of the particular MIP problem being solved, evolving a problem-specific node selection method. The evolved metho...