12873659
TARA: Thermal-Aware Routing Algorithm for Implanted Sensor Networks
Implanted biological sensors are a special class of wireless sensor networks that are used in-vivo for various medical applications. One of the major challenges of continuous in-vivo sensing is the heat generated by the implanted sensors due to communication radiation and circuitry power consumption. This paper addresses the issues of routing in implanted sensor networks. We propose a thermal-aware routing protocol that routes the data away from high temperature areas (hot spots). With this protocol each node estimates temperature change of its neighbors and routes packets around the hot spot area by a withdraw strategy. The proposed protocol can achieve a better balance of temperature rise and only experience a modest increased delay compared with shortest hop, but thermal-awareness also indicates the capability of load balance, which leads to less packet loss in high load situations.
1274772
Supporting persistent social groups in ubiquitous computing environments using context-aware ephemeral group service
We analyze the role of the social group in a ubiquitous computing (Ubicomp) environment as a source of contextual information. A model is presented to address the social group member's perceptions of how devices in a ubicomp environment should aid them in collaboration. Based on the model a distributed context-aware group membership management scheme is developed. We then present a prototype implementation for a context-aware ephemeral group membership management scheme, along with a sample application, and experimental results that demonstrate the feasibility of our system.
18593367
Biosec: a biometric based approach for securing communication in wireless networks of biosensors implanted in the human body
Advances in microelectronics, material science and wireless technology have led to the development of sensors that can be used for accurate monitoring of inaccessible environments. Health monitoring, telemedicine, military and environmental monitoring are some of the applications where sensors can be used. The sensors implanted inside the human body to monitor parts of the body are called biosensors. These biosensors form a network and collectively monitor the health condition of their carrier or host. Health monitoring involves collection of data about vital body parameters from different parts of the body and making decisions based on it. This information is of personal nature and is required to be secured. Insecurity may also lead to dangerous consequences. Due to the extreme constraints of energy, memory and computation securing the communication among the biosensors is not a trivial problem. Key distribution is central to any security mechanism. In this paper we propose an approach wherein, biometrics derived from the body are used for securing the keying material. This method obviates the need for expensive computation and avoids unnecessary communication making our approach novel compared to existing approaches.
2580676
Adaptive Distributed Dynamic Channel Allocation for Wireless Networks
Channel allocation schemes in a mobile computing (wireless) environment can be either static or dynamic. Static allocation offers negligible channel acquisition time and zero message complexity and works well at a low system load; the performance steadily decreases as system load increases since many calls are dropped. In the case of even temporary hot spots many calls may be dropped by a heavily loaded switching station even when there are enough idle channels in the interference region of that station. On the other hand, dynamic schemes provide better utilization of the channels at higher loads albeit at the cost of higher channel acquisition time and some additional control messages. Our purpose in the present paper is to propose a combined channel allocation scheme so that each switching station can tune to its own load independent of other stations in its interference region; the objective is to minimize the call drop rate and at the same time maintain a minimum average channel acquisition time and minimum control message complexity.
14536242
On maximizing lifetime of multicast trees in wireless ad hoc networks
We present a distributed algorithm called L-REMiTfor extending the lifetime of a source-based multicast tree in wireless ad hoc networks (WANET). The lifetime of a multicast tree is the duration from the formation of the tree to the time when the first node fails due to battery energy exhaustion. L-REMiT assumes that the energy consumed to forward a packet is proportional to the forwarding distance and that WANET nodes can dynamically adjust their transmission power. The task of extending the lifetime of a multicast tree is formulated as the task of extending the lifetime of bottleneck nodes in the tree. The number of multicast packets which a bottleneck node can forward, as determined by its residual battery energy and the distance of its farthest child node, is minimum over all the nodes in the multicast tree. Lifetime of a bottleneck node is improved by reassigning its farthest children to other nodes in the tree with the goal of improving the lifetime of the multicast tree. Nodes only require information from their neighbors for refining the tree in a distributed manner. Simulation results show that L-REMiT has low overhead and performs better than BIP/MIP and EWMA algorithms
1499493
Bandwidth-Optimal Complete Exchange on Wormhole-Routed 2D/3D Torus Networks: A Diagonal-Propagation Approach
All-to-all personalized communication, or complete exchange, is at the heart of numerous applications in parallel computing. Several complete exchange algorithms have been proposed in the literature for wormhole meshes. However, these algorithms, when applied to tori, cannot take advantage of wrap-around interconnections to implement complete exchange with reduced latency. In this paper, a new diagonal-propagation approach is proposed to develop a set of complete exchange algorithms for 2D and 3D tori. This approach exploits the symmetric interconnections of tori and allows to develop a communication schedule consisting of several contention-free phases. These algorithms are indirect in nature and they use message combining to reduce the number of phases (message start-ups). It is shown that these algorithms effectively use the bisection bandwidth of a torus which is twice that for an equal sized mesh, to achieve complete exchange in time which is almost half of the best known complete exchange time on an equal sized mesh. The effectiveness of these algorithms is verified through simulation studies for varying system and technological parameters. It is also demonstrated that synchronous implementations of these algorithms (by introducing barriers between phases) lead to reduced latency for complete exchange with large messages, while the asynchronous ones are better for smaller messages.
8985111
AI Planning Versus Manufacturing-Operation Planning: A Case Study
Although AI planning techniques can potentially be useful in several manufacturing domains, this potential remains largely unrealized. In order to adapt AI planning techniques to manufacturing, it is important to develop more realistic and robust ways to address issues important to manufacturing engineers. Furthermore, by investigating such issues, AI researchers may he able to discover principles that are relevant for AI planning in general. As an example, in this paper we describe the techniques for manufacturing-operation planning used in IMACS (Interactive Manufacturability Analysis and Critiquing System), and compare and contrast them with the techniques used in classical AI planning systems. We describe how one of IMACS's planning techniques may be useful for AI planning in general--and as an example, we describe how it helps to explain a puzzling complexity result in AI planning.
13998462
Geometric algorithms for computing cutter engagement functions in 2.5D milling operations
Cutter engagement is a measure that describes what portion of the cutter is involved in machining at a given instant of time. During profile milling of complex geometries, cutter engagement varies significantly along the cutter path. Cutter engagement information helps in determining the efficiency of the cutter path and also helps in improving it by adjusting the feed rate. This paper describes geometric algorithms for computing piece-wise continuous closed-form cutter engagement functions for 2.5D milling operations. The results produced by our algorithm are compared with the results obtained by discrete simulations of the cutting process and appear to match very well.
6938010
Flip-flop chaining architecture for power-efficient scan during test application
Power dissipation in CMOS circuits during test time poses a crucial bottleneck for circuit performance and robustness. The power consumption due to switching activity while scan-in of test vectors and scan-out of responses is of particular concern. In this paper a methodology for scan chain modification and test vector adaptation is proposed to effectively reduce the scan test power consumption by controlling this switching activity. Proposed approach, unlike the many in published literature, does not incorporate reordering of scan cells; thus avoiding timing and routing overheads. ATPG software ATALANTA was used for test vector generation. The algorithm was verified for ISCAS’89 benchmark circuits, where it showed as much as 27.3% of reduction in switching activity during scan operations.
12850641
Fault-oriented Test Generation for Multicast Routing Protocol Design
We present a new algorithm for automatic test generation for multicast routing. Our algorithm processes a finite state machine (FSM) model of the protocol and uses a mix of forward and backward search techniques to generate the tests. The output tests include a set of topologies, protocol events and network failures, that lead to violation of protocol correctness and behavioral requirements. We target protocol robustness in specific, and do not attempt to verify other properties in this paper. We apply our method to a multicast routing protocol; PIM-DM, and investigate its behavior in the presence of selective packet loss on LANs and router crashes. Our study unveils several robustness violations in PIM-DM, for which we suggest fixes with the aid of the presented algorithm.
2930416
Towards multiprocessor feature recognition
Abstract The availability of low-cost computational power is enabling the development of increasingly sophisticated cad software. Automation of design and manufacturing activities poses many difficult computational problems—significant among them is how to develop interactive systems that enable designers to explore and experiment with alternative ideas. As more downstream manufacturing activities are considered during the design phase, computational costs become problematic. Creating working software-based solutions requires a sophisticated allocation of computational resources in order to perform realistic design analyses and generate feedback. This paper presents our initial efforts to employ multiprocessor algorithms to recognize machining features from solid models of parts with large numbers of features and many geometric and topological entities. Our goal is to outline how improvements in computation time can be obtained by migrating existing software tools to multiprocessor architectures. An implementation of our approach is discussed.